pigpiod_if2(3)

NAME
pigpiod_if2 - A C library to interface to the pigpio daemon.

SYNOPSIS
#include <pigpiod_if2.h> gcc -Wall -pthread -o prog prog.c -lpigpiod_if2 -lrt
 ./prog

DESCRIPTION
pigpiod_if2 is a C library for the Raspberry which allows control of the GPIO via the socket interface to the pigpio daemon.

  Features
o hardware timed PWM on any of GPIO 0-31
o hardware timed servo pulses on any of GPIO 0-31
o callbacks when any of GPIO 0-31 change state
o callbacks at timed intervals
o reading/writing all of the GPIO in a bank as one operation
o individually setting GPIO modes, reading and writing
o notifications when any of GPIO 0-31 change state
o the construction of output waveforms with microsecond timing
o rudimentary permission control over GPIO
o a simple interface to start and stop new threads
o I2C, SPI, and serial link wrappers
o creating and running scripts on the pigpio daemon

  GPIO
ALL GPIO are identified by their Broadcom number.

  Notes
The PWM and servo pulses are timed using the DMA and PWM/PCM peripherals.

  Usage
Include <pigpiod_if2.h> in your source files.
Assuming your source is in prog.c use the following command to build
    gcc -Wall -pthread -o prog prog.c -lpigpiod_if2 -lrt
to run make sure the pigpio daemon is running
    sudo pigpiod
     ./prog # sudo is not required to run programs linked to pigpiod_if2
For examples see x_pigpiod_if2.c within the pigpio archive file.

  Notes
All the functions which return an int return < 0 on error

OVERVIEW

  ESSENTIAL
pigpio_start Connects to a pigpio daemon
pigpio_stop Disconnects from a pigpio daemon

  BASIC
set_mode Set a GPIO mode
get_mode Get a GPIO mode
set_pull_up_down Set/clear GPIO pull up/down resistor
gpio_read Read a GPIO
gpio_write Write a GPIO

  PWM (overrides servo commands on same GPIO)
set_PWM_dutycycle Start/stop PWM pulses on a GPIO
set_PWM_frequency Configure PWM frequency for a GPIO
set_PWM_range Configure PWM range for a GPIO
get_PWM_dutycycle Get the PWM dutycycle in use on a GPIO
get_PWM_frequency Get configured PWM frequency for a GPIO
get_PWM_range Get configured PWM range for a GPIO
get_PWM_real_range Get underlying PWM range for a GPIO

  Servo (overrides PWM commands on same GPIO)
set_servo_pulsewidth Start/stop servo pulses on a GPIO
get_servo_pulsewidth Get the servo pulsewidth in use on a GPIO

  INTERMEDIATE
gpio_trigger Send a trigger pulse to a GPIO.
set_watchdog Set a watchdog on a GPIO.
read_bank_1 Read all GPIO in bank 1
read_bank_2 Read all GPIO in bank 2
clear_bank_1 Clear selected GPIO in bank 1
clear_bank_2 Clear selected GPIO in bank 2
set_bank_1 Set selected GPIO in bank 1
set_bank_2 Set selected GPIO in bank 2
callback Create GPIO level change callback
callback_ex Create GPIO level change callback, extended
callback_cancel Cancel a callback
wait_for_edge Wait for GPIO level change
start_thread Start a new thread
stop_thread Stop a previously started thread

  ADVANCED
notify_open Request a notification handle
notify_begin Start notifications for selected GPIO
notify_pause Pause notifications
notify_close Close a notification
hardware_clock Start hardware clock on supported GPIO
hardware_PWM Start hardware PWM on supported GPIO
set_glitch_filter Set a glitch filter on a GPIO
set_noise_filter Set a noise filter on a GPIO
set_pad_strength Sets a pads drive strength
get_pad_strength Gets a pads drive strength
shell_ Executes a shell command

  Custom
custom_1 User custom function 1
custom_2 User custom function 2

  Events
event_callback Sets a callback for an event
event_callback_ex Sets a callback for an event, extended
event_callback_cancel Cancel an event callback
event_trigger Triggers an event
wait_for_event Wait for an event

  Scripts
store_script Store a script
run_script Run a stored script
update_script Set a scripts parameters
script_status Get script status and parameters
stop_script Stop a running script
delete_script Delete a stored script

  I2C
i2c_open Opens an I2C device
i2c_close Closes an I2C device
i2c_write_quick smbus write quick
i2c_read_byte smbus read byte
i2c_write_byte smbus write byte
i2c_read_byte_data smbus read byte data
i2c_write_byte_data smbus write byte data
i2c_read_word_data smbus read word data
i2c_write_word_data smbus write word data
i2c_read_block_data smbus read block data
i2c_write_block_data smbus write block data
i2c_read_i2c_block_data smbus read I2C block data
i2c_write_i2c_block_data smbus write I2C block data
i2c_read_device Reads the raw I2C device
i2c_write_device Writes the raw I2C device
i2c_process_call smbus process call
i2c_block_process_call smbus block process call
i2c_zip Performs multiple I2C transactions

  I2C BIT BANG
bb_i2c_open Opens GPIO for bit banging I2C
bb_i2c_close Closes GPIO for bit banging I2C
bb_i2c_zip Performs bit banged I2C transactions

  I2C/SPI SLAVE
bsc_xfer I2C/SPI as slave transfer
bsc_i2c I2C as slave transfer

  SERIAL
serial_open Opens a serial device
serial_close Closes a serial device
serial_read_byte Reads a byte from a serial device
serial_write_byte Writes a byte to a serial device
serial_read Reads bytes from a serial device
serial_write Writes bytes to a serial device
serial_data_available Returns number of bytes ready to be read

  SERIAL BIT BANG (read only)
bb_serial_read_open Opens a GPIO for bit bang serial reads
bb_serial_read_close Closes a GPIO for bit bang serial reads
bb_serial_invert Invert serial logic (1 invert, 0 normal)
bb_serial_read Reads bit bang serial data from a GPIO

  SPI
spi_open Opens a SPI device
spi_close Closes a SPI device
spi_read Reads bytes from a SPI device
spi_write Writes bytes to a SPI device
spi_xfer Transfers bytes with a SPI device

  SPI BIT BANG
bb_spi_open Opens GPIO for bit banging SPI
bb_spi_close Closes GPIO for bit banging SPI
bb_spi_xfer Transfers bytes with bit banging SPI

  FILES
file_open Opens a file
file_close Closes a file
file_read Reads bytes from a file
file_write Writes bytes to a file
file_seek Seeks to a position within a file
file_list List files which match a pattern

  WAVES
wave_clear Deletes all waveforms
wave_add_new Starts a new waveform
wave_add_generic Adds a series of pulses to the waveform
wave_add_serial Adds serial data to the waveform
wave_create Creates a waveform from added data
wave_delete Deletes one or more waveforms
wave_send_once Transmits a waveform once
wave_send_repeat Transmits a waveform repeatedly
wave_send_using_mode Transmits a waveform in the chosen mode
wave_chain Transmits a chain of waveforms
wave_tx_at Returns the current transmitting waveform
wave_tx_busy Checks to see if the waveform has ended
wave_tx_stop Aborts the current waveform
wave_get_cbs Length in cbs of the current waveform
wave_get_high_cbs Length of longest waveform so far
wave_get_max_cbs Absolute maximum allowed cbs
wave_get_micros Length in micros of the current waveform
wave_get_high_micros Length of longest waveform so far
wave_get_max_micros Absolute maximum allowed micros
wave_get_pulses Length in pulses of the current waveform
wave_get_high_pulses Length of longest waveform so far
wave_get_max_pulses Absolute maximum allowed pulses

  UTILITIES
get_current_tick Get current tick (microseconds)
get_hardware_revision Get hardware revision
get_pigpio_version Get the pigpio version
pigpiod_if_version Get the pigpiod_if2 version
pigpio_error Get a text description of an error code.
time_sleep Sleeps for a float number of seconds
time_time Float number of seconds since the epoch

FUNCTIONS

double time_time(void)

    Return the current time in seconds since the Epoch.

void time_sleep(double seconds)

    Delay execution for a given number of seconds.
        seconds: the number of seconds to delay.

char *pigpio_error(int errnum)

    Return a text description for an error code.
        errnum: the error code.

unsigned pigpiod_if_version(void)

    Return the pigpiod_if2 version.

pthread_t *start_thread(gpioThreadFunc_t thread_func, void *userdata)

    Starts a new thread of execution with thread_func as the main routine.
        thread_func: the main function for the new thread.
           userdata: a pointer to an arbitrary argument.
    Returns a pointer to pthread_t if OK, otherwise NULL.
    The function is passed the single argument userdata.
    The thread can be cancelled by passing the pointer to pthread_t to stop_thread.

void stop_thread(pthread_t *pth)

    Cancels the thread pointed at by pth.
        pth: the thread to be stopped.
    No value is returned.
    The thread to be stopped should have been started with start_thread.

int pigpio_start(char *addrStr, char *portStr)

    Connect to the pigpio daemon. Reserving command and notification streams.
        addrStr: specifies the host or IP address of the Pi running the
                 pigpio daemon.  It may be NULL in which case localhost
                 is used unless overridden by the PIGPIO_ADDR environment
                 variable.
        portStr: specifies the port address used by the Pi running the
                 pigpio daemon.  It may be NULL in which case "8888"
                 is used unless overridden by the PIGPIO_PORT environment
                 variable.
    Returns an integer value greater than or equal to zero if OK.
    This value is passed to the GPIO routines to specify the Pi to be operated on.

void pigpio_stop(int pi)

    Terminates the connection to a pigpio daemon and releases resources used by the library.
        pi: >=0 (as returned by pigpio_start).

int set_mode(int pi, unsigned gpio, unsigned mode)

    Set the GPIO mode.
          pi: >=0 (as returned by pigpio_start).
        gpio: 0-53.
        mode: PI_INPUT, PI_OUTPUT, PI_ALT0, PI_ALT1,
              PI_ALT2, PI_ALT3, PI_ALT4, PI_ALT5.
    Returns 0 if OK, otherwise PI_BAD_GPIO, PI_BAD_MODE, or PI_NOT_PERMITTED.

int get_mode(int pi, unsigned gpio)

    Get the GPIO mode.
          pi: >=0 (as returned by pigpio_start).
        gpio: 0-53.
    Returns the GPIO mode if OK, otherwise PI_BAD_GPIO.

int set_pull_up_down(int pi, unsigned gpio, unsigned pud)

    Set or clear the GPIO pull-up/down resistor.
          pi: >=0 (as returned by pigpio_start).
        gpio: 0-53.
         pud: PI_PUD_UP, PI_PUD_DOWN, PI_PUD_OFF.
    Returns 0 if OK, otherwise PI_BAD_GPIO, PI_BAD_PUD, or PI_NOT_PERMITTED.

int gpio_read(int pi, unsigned gpio)

    Read the GPIO level.
          pi: >=0 (as returned by pigpio_start).
        gpio:0-53.
    Returns the GPIO level if OK, otherwise PI_BAD_GPIO.

int gpio_write(int pi, unsigned gpio, unsigned level)

    Write the GPIO level.
           pi: >=0 (as returned by pigpio_start).
         gpio: 0-53.
        level: 0, 1.
    Returns 0 if OK, otherwise PI_BAD_GPIO, PI_BAD_LEVEL, or PI_NOT_PERMITTED.
    Notes
    If PWM or servo pulses are active on the GPIO they are switched off.

int set_PWM_dutycycle(int pi, unsigned user_gpio, unsigned dutycycle)

    Start (non-zero dutycycle) or stop (0) PWM pulses on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
        dutycycle: 0-range (range defaults to 255).
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_DUTYCYCLE, or PI_NOT_PERMITTED. Notes
    The set_PWM_range function may be used to change the default range of 255.

int get_PWM_dutycycle(int pi, unsigned user_gpio)

    Return the PWM dutycycle in use on a GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO or PI_NOT_PWM_GPIO.
    For normal PWM the dutycycle will be out of the defined range for the GPIO (see get_PWM_range).
    If a hardware clock is active on the GPIO the reported dutycycle will be 500000 (500k) out of 1000000 (1M).
    If hardware PWM is active on the GPIO the reported dutycycle will be out of a 1000000 (1M).

int set_PWM_range(int pi, unsigned user_gpio, unsigned range)

    Set the range of PWM values to be used on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
            range: 25-40000.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_DUTYRANGE, or PI_NOT_PERMITTED.
    Notes
    If PWM is currently active on the GPIO its dutycycle will be scaled to reflect the new range.
    The real range, the number of steps between fully off and fully on for each of the 18 available GPIO frequencies is
          25(#1),    50(#2),   100(#3),   125(#4),    200(#5),    250(#6),
         400(#7),   500(#8),   625(#9),   800(#10),  1000(#11),  1250(#12),
        2000(#13), 2500(#14), 4000(#15), 5000(#16), 10000(#17), 20000(#18)
    The real value set by set_PWM_range is (dutycycle * real range) / range.

int get_PWM_range(int pi, unsigned user_gpio)

    Get the range of PWM values being used on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
    Returns the dutycycle range used for the GPIO if OK, otherwise PI_BAD_USER_GPIO.
    If a hardware clock or hardware PWM is active on the GPIO the reported range will be 1000000 (1M).

int get_PWM_real_range(int pi, unsigned user_gpio)

    Get the real underlying range of PWM values being used on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
    Returns the real range used for the GPIO if OK, otherwise PI_BAD_USER_GPIO.
    If a hardware clock is active on the GPIO the reported real range will be 1000000 (1M).
    If hardware PWM is active on the GPIO the reported real range will be approximately 250M divided by the set PWM frequency.

int set_PWM_frequency(int pi, unsigned user_gpio, unsigned frequency)

    Set the frequency (in Hz) of the PWM to be used on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
        frequency: >=0 (Hz).
    Returns the numerically closest frequency if OK, otherwise PI_BAD_USER_GPIO or PI_NOT_PERMITTED.
    If PWM is currently active on the GPIO it will be switched off and then back on at the new frequency.
    Each GPIO can be independently set to one of 18 different PWM frequencies.
    The selectable frequencies depend upon the sample rate which may be 1, 2, 4, 5, 8, or 10 microseconds (default 5). The sample rate is set when the pigpio daemon is started.
    The frequencies for each sample rate are:
                               Hertz
               1: 40000 20000 10000 8000 5000 4000 2500 2000 1600
                   1250  1000   800  500  400  250  200  100   50
               2: 20000 10000  5000 4000 2500 2000 1250 1000  800
                    625   500   400  250  200  125  100   50   25
               4: 10000  5000  2500 2000 1250 1000  625  500  400
                    313   250   200  125  100   63   50   25   13
        sample
         rate
         (us)  5:  8000  4000  2000 1600 1000  800  500  400  320
                    250   200   160  100   80   50   40   20   10
               8:  5000  2500  1250 1000  625  500  313  250  200
                    156   125   100   63   50   31   25   13    6
              10:  4000  2000  1000  800  500  400  250  200  160
                    125   100    80   50   40   25   20   10    5

int get_PWM_frequency(int pi, unsigned user_gpio)

    Get the frequency of PWM being used on the GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
    For normal PWM the frequency will be that defined for the GPIO by set_PWM_frequency.
    If a hardware clock is active on the GPIO the reported frequency will be that set by hardware_clock.
    If hardware PWM is active on the GPIO the reported frequency will be that set by hardware_PWM.
    Returns the frequency (in hertz) used for the GPIO if OK, otherwise PI_BAD_USER_GPIO.

int set_servo_pulsewidth(int pi, unsigned user_gpio, unsigned pulsewidth)

    Start (500-2500) or stop (0) servo pulses on the GPIO.
                pi: >=0 (as returned by pigpio_start).
         user_gpio: 0-31.
        pulsewidth: 0 (off), 500 (anti-clockwise) - 2500 (clockwise).
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_PULSEWIDTH or PI_NOT_PERMITTED.
    The selected pulsewidth will continue to be transmitted until changed by a subsequent call to set_servo_pulsewidth.
    The pulsewidths supported by servos varies and should probably be determined by experiment. A value of 1500 should always be safe and represents the mid-point of rotation.
    You can DAMAGE a servo if you command it to move beyond its limits.
    OTHER UPDATE RATES:
    This function updates servos at 50Hz. If you wish to use a different update frequency you will have to use the PWM functions.
        Update Rate (Hz)     50   100  200  400  500
        1E6/Hz            20000 10000 5000 2500 2000
    Firstly set the desired PWM frequency using set_PWM_frequency.
    Then set the PWM range using set_PWM_range to 1E6/Hz. Doing this allows you to use units of microseconds when setting the servo pulsewidth.
    E.g. If you want to update a servo connected to GPIO 25 at 400Hz
        set_PWM_frequency(25, 400);
        set_PWM_range(25, 2500);
    Thereafter use the set_PWM_dutycycle function to move the servo, e.g. set_PWM_dutycycle(25, 1500) will set a 1500 us pulse.

int get_servo_pulsewidth(int pi, unsigned user_gpio)

    Return the servo pulsewidth in use on a GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO or PI_NOT_SERVO_GPIO.

int notify_open(int pi)

    Get a free notification handle.
        pi: >=0 (as returned by pigpio_start).
    Returns a handle greater than or equal to zero if OK, otherwise PI_NO_HANDLE.
    A notification is a method for being notified of GPIO state changes via a pipe.
    Pipes are only accessible from the local machine so this function serves no purpose if you are using the library from a remote machine. The in-built (socket) notifications provided by callback should be used instead.
    Notifications for handle x will be available at the pipe named /dev/pigpiox (where x is the handle number). E.g. if the function returns 15 then the notifications must be read from /dev/pigpio15.

int notify_begin(int pi, unsigned handle, uint32_t bits)

    Start notifications on a previously opened handle.
            pi: >=0 (as returned by pigpio_start).
        handle: 0-31 (as returned by notify_open)
          bits: a mask indicating the GPIO to be notified.
    Returns 0 if OK, otherwise PI_BAD_HANDLE.
    The notification sends state changes for each GPIO whose corresponding bit in bits is set.
    Each notification occupies 12 bytes in the fifo as follows:
        typedef struct
        {
           uint16_t seqno;
           uint16_t flags;
           uint32_t tick;
           uint32_t level;
        } gpioReport_t;
    seqno: starts at 0 each time the handle is opened and then increments by one for each report.
    flags: three flags are defined, PI_NTFY_FLAGS_WDOG, PI_NTFY_FLAGS_ALIVE, and PI_NTFY_FLAGS_EVENT.
    If bit 5 is set (PI_NTFY_FLAGS_WDOG) then bits 0-4 of the flags indicate a GPIO which has had a watchdog timeout.
    If bit 6 is set (PI_NTFY_FLAGS_ALIVE) this indicates a keep alive signal on the pipe/socket and is sent once a minute in the absence of other notification activity.
    If bit 7 is set (PI_NTFY_FLAGS_EVENT) then bits 0-4 of the flags indicate an event which has been triggered.
    tick: the number of microseconds since system boot. It wraps around after 1h12m.
    level: indicates the level of each GPIO. If bit 1<<x is set then GPIO x is high.

int notify_pause(int pi, unsigned handle)

    Pause notifications on a previously opened handle.
            pi: >=0 (as returned by pigpio_start).
        handle: 0-31 (as returned by notify_open)
    Returns 0 if OK, otherwise PI_BAD_HANDLE.
    Notifications for the handle are suspended until notify_begin is called again.

int notify_close(int pi, unsigned handle)

    Stop notifications on a previously opened handle and release the handle for reuse.
            pi: >=0 (as returned by pigpio_start).
        handle: 0-31 (as returned by notify_open)
    Returns 0 if OK, otherwise PI_BAD_HANDLE.

int set_watchdog(int pi, unsigned user_gpio, unsigned timeout)

    Sets a watchdog for a GPIO.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
          timeout: 0-60000.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO or PI_BAD_WDOG_TIMEOUT.
    The watchdog is nominally in milliseconds.
    Only one watchdog may be registered per GPIO.
    The watchdog may be cancelled by setting timeout to 0.
    Once a watchdog has been started callbacks for the GPIO will be triggered every timeout interval after the last GPIO activity.
    The callback will receive the special level PI_TIMEOUT.

int set_glitch_filter(int pi, unsigned user_gpio, unsigned steady)

    Sets a glitch filter on a GPIO.
    Level changes on the GPIO are not reported unless the level has been stable for at least steady microseconds. The level is then reported. Level changes of less than steady microseconds are ignored.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31
           steady: 0-300000
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, or PI_BAD_FILTER.
    This filter affects the GPIO samples returned to callbacks set up with callback, callback_ex and wait_for_edge.
    It does not affect levels read by gpio_read, read_bank_1, or read_bank_2.
    Each (stable) edge will be timestamped steady microseconds after it was first detected.

int set_noise_filter(int pi, unsigned user_gpio, unsigned steady, unsigned active)

    Sets a noise filter on a GPIO.
    Level changes on the GPIO are ignored until a level which has been stable for steady microseconds is detected. Level changes on the GPIO are then reported for active microseconds after which the process repeats.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31
           steady: 0-300000
           active: 0-1000000
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, or PI_BAD_FILTER.
    This filter affects the GPIO samples returned to callbacks set up with callback, callback_ex and wait_for_edge.
    It does not affect levels read by gpio_read, read_bank_1, or read_bank_2.
    Level changes before and after the active period may be reported. Your software must be designed to cope with such reports.

uint32_t read_bank_1(int pi)

    Read the levels of the bank 1 GPIO (GPIO 0-31).
        pi: >=0 (as returned by pigpio_start).
    The returned 32 bit integer has a bit set if the corresponding GPIO is logic 1. GPIO n has bit value (1<<n).

uint32_t read_bank_2(int pi)

    Read the levels of the bank 2 GPIO (GPIO 32-53).
        pi: >=0 (as returned by pigpio_start).
    The returned 32 bit integer has a bit set if the corresponding GPIO is logic 1. GPIO n has bit value (1<<(n-32)).

int clear_bank_1(int pi, uint32_t bits)

    Clears GPIO 0-31 if the corresponding bit in bits is set.
          pi: >=0 (as returned by pigpio_start).
        bits: a bit mask with 1 set if the corresponding GPIO is
              to be cleared.
    Returns 0 if OK, otherwise PI_SOME_PERMITTED.
    A status of PI_SOME_PERMITTED indicates that the user is not allowed to write to one or more of the GPIO.

int clear_bank_2(int pi, uint32_t bits)

    Clears GPIO 32-53 if the corresponding bit (0-21) in bits is set.
          pi: >=0 (as returned by pigpio_start).
        bits: a bit mask with 1 set if the corresponding GPIO is
              to be cleared.
    Returns 0 if OK, otherwise PI_SOME_PERMITTED.
    A status of PI_SOME_PERMITTED indicates that the user is not allowed to write to one or more of the GPIO.

int set_bank_1(int pi, uint32_t bits)

    Sets GPIO 0-31 if the corresponding bit in bits is set.
          pi: >=0 (as returned by pigpio_start).
        bits: a bit mask with 1 set if the corresponding GPIO is
              to be set.
    Returns 0 if OK, otherwise PI_SOME_PERMITTED.
    A status of PI_SOME_PERMITTED indicates that the user is not allowed to write to one or more of the GPIO.

int set_bank_2(int pi, uint32_t bits)

    Sets GPIO 32-53 if the corresponding bit (0-21) in bits is set.
          pi: >=0 (as returned by pigpio_start).
        bits: a bit mask with 1 set if the corresponding GPIO is
              to be set.
    Returns 0 if OK, otherwise PI_SOME_PERMITTED.
    A status of PI_SOME_PERMITTED indicates that the user is not allowed to write to one or more of the GPIO.

int hardware_clock(int pi, unsigned gpio, unsigned clkfreq)

    Starts a hardware clock on a GPIO at the specified frequency. Frequencies above 30MHz are unlikely to work.
               pi: >=0 (as returned by pigpio_start).
             gpio: see description
        frequency: 0 (off) or 4689-250M (13184-375M for the BCM2711)
    Returns 0 if OK, otherwise PI_NOT_PERMITTED, PI_BAD_GPIO, PI_NOT_HCLK_GPIO, PI_BAD_HCLK_FREQ,or PI_BAD_HCLK_PASS.
    The same clock is available on multiple GPIO. The latest frequency setting will be used by all GPIO which share a clock.
    The GPIO must be one of the following.
        4   clock 0  All models
        5   clock 1  All models but A and B (reserved for system use)
        6   clock 2  All models but A and B
        20  clock 0  All models but A and B
        21  clock 1  All models but A and Rev.2 B (reserved for system use)
        32  clock 0  Compute module only
        34  clock 0  Compute module only
        42  clock 1  Compute module only (reserved for system use)
        43  clock 2  Compute module only
        44  clock 1  Compute module only (reserved for system use)
    Access to clock 1 is protected by a password as its use will likely crash the Pi. The password is given by or'ing 0x5A000000 with the GPIO number.

int hardware_PWM(int pi, unsigned gpio, unsigned PWMfreq, uint32_t PWMduty)

    Starts hardware PWM on a GPIO at the specified frequency and dutycycle. Frequencies above 30MHz are unlikely to work.
    NOTE: Any waveform started by wave_send_* or wave_chain will be cancelled.
    This function is only valid if the pigpio main clock is PCM. The main clock defaults to PCM but may be overridden when the pigpio daemon is started (option -t).
             pi: >=0 (as returned by pigpio_start).
           gpio: see descripton
        PWMfreq: 0 (off) or 1-125M (1-187.5M for the BCM2711)
        PWMduty: 0 (off) to 1000000 (1M)(fully on)
    Returns 0 if OK, otherwise PI_NOT_PERMITTED, PI_BAD_GPIO, PI_NOT_HPWM_GPIO, PI_BAD_HPWM_DUTY, PI_BAD_HPWM_FREQ, or PI_HPWM_ILLEGAL.
    The same PWM channel is available on multiple GPIO. The latest frequency and dutycycle setting will be used by all GPIO which share a PWM channel.
    The GPIO must be one of the following.
        12  PWM channel 0  All models but A and B
        13  PWM channel 1  All models but A and B
        18  PWM channel 0  All models
        19  PWM channel 1  All models but A and B
        40  PWM channel 0  Compute module only
        41  PWM channel 1  Compute module only
        45  PWM channel 1  Compute module only
        52  PWM channel 0  Compute module only
        53  PWM channel 1  Compute module only
    The actual number of steps beween off and fully on is the integral part of 250M/PWMfreq (375M/PWMfreq for the BCM2711).
    The actual frequency set is 250M/steps (375M/steps for the BCM2711).
    There will only be a million steps for a PWMfreq of 250 (375 for the BCM2711). Lower frequencies will have more steps and higher frequencies will have fewer steps. PWMduty is automatically scaled to take this into account.

uint32_t get_current_tick(int pi)

    Gets the current system tick.
        pi: >=0 (as returned by pigpio_start).
    Tick is the number of microseconds since system boot.
    As tick is an unsigned 32 bit quantity it wraps around after 2**32 microseconds, which is approximately 1 hour 12 minutes.

uint32_t get_hardware_revision(int pi)

    Get the Pi's hardware revision number.
        pi: >=0 (as returned by pigpio_start).
    The hardware revision is the last few characters on the Revision line of /proc/cpuinfo.
    If the hardware revision can not be found or is not a valid hexadecimal number the function returns 0.
    The revision number can be used to determine the assignment of GPIO to pins (see gpio).
    There are at least three types of board.
    Type 1 boards have hardware revision numbers of 2 and 3.
    Type 2 boards have hardware revision numbers of 4, 5, 6, and 15.
    Type 3 boards have hardware revision numbers of 16 or greater.

uint32_t get_pigpio_version(int pi)

    Returns the pigpio version.
        pi: >=0 (as returned by pigpio_start).

int wave_clear(int pi)

    This function clears all waveforms and any data added by calls to the wave_add_* functions.
        pi: >=0 (as returned by pigpio_start).
    Returns 0 if OK.

int wave_add_new(int pi)

    This function starts a new empty waveform. You wouldn't normally need to call this function as it is automatically called after a waveform is created with the wave_create function.
        pi: >=0 (as returned by pigpio_start).
    Returns 0 if OK.

int wave_add_generic(int pi, unsigned numPulses, gpioPulse_t *pulses)

    This function adds a number of pulses to the current waveform.
               pi: >=0 (as returned by pigpio_start).
        numPulses: the number of pulses.
           pulses: an array of pulses.
    Returns the new total number of pulses in the current waveform if OK, otherwise PI_TOO_MANY_PULSES.
    The pulses are interleaved in time order within the existing waveform (if any).
    Merging allows the waveform to be built in parts, that is the settings for GPIO#1 can be added, and then GPIO#2 etc.
    If the added waveform is intended to start after or within the existing waveform then the first pulse should consist solely of a delay.

int wave_add_serial(int pi, unsigned user_gpio, unsigned baud, unsigned data_bits, unsigned stop_bits, unsigned offset, unsigned numBytes, char *str)

    This function adds a waveform representing serial data to the existing waveform (if any). The serial data starts offset microseconds from the start of the waveform.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
             baud: 50-1000000
        data_bits: number of data bits (1-32)
        stop_bits: number of stop half bits (2-8)
           offset: >=0
         numBytes: >=1
              str: an array of chars.
    Returns the new total number of pulses in the current waveform if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_WAVE_BAUD, PI_BAD_DATABITS, PI_BAD_STOP_BITS, PI_TOO_MANY_CHARS, PI_BAD_SER_OFFSET, or PI_TOO_MANY_PULSES.
    NOTES:
    The serial data is formatted as one start bit, data_bits data bits, and stop_bits/2 stop bits.
    It is legal to add serial data streams with different baud rates to the same waveform.
    numBytes is the number of bytes of data in str.
    The bytes required for each character depend upon data_bits.
    For data_bits 1-8 there will be one byte per character.
    For data_bits 9-16 there will be two bytes per character.
    For data_bits 17-32 there will be four bytes per character.

int wave_create(int pi)

    This function creates a waveform from the data provided by the prior calls to the wave_add_* functions. Upon success a wave id greater than or equal to 0 is returned, otherwise PI_EMPTY_WAVEFORM, PI_TOO_MANY_CBS, PI_TOO_MANY_OOL, or PI_NO_WAVEFORM_ID.
        pi: >=0 (as returned by pigpio_start).
    The data provided by the wave_add_* functions is consumed by this function.
    As many waveforms may be created as there is space available. The wave id is passed to wave_send_* to specify the waveform to transmit.
    Normal usage would be
    Step 1. wave_clear to clear all waveforms and added data.
    Step 2. wave_add_* calls to supply the waveform data.
    Step 3. wave_create to create the waveform and get a unique id
    Repeat steps 2 and 3 as needed.
    Step 4. wave_send_* with the id of the waveform to transmit.
    A waveform comprises one or more pulses. Each pulse consists of a gpioPulse_t structure.
        typedef struct
        {
           uint32_t gpioOn;
           uint32_t gpioOff;
           uint32_t usDelay;
        } gpioPulse_t;
    The fields specify
    1) the GPIO to be switched on at the start of the pulse.
    2) the GPIO to be switched off at the start of the pulse.
    3) the delay in microseconds before the next pulse.
    Any or all the fields can be zero. It doesn't make any sense to set all the fields to zero (the pulse will be ignored).
    When a waveform is started each pulse is executed in order with the specified delay between the pulse and the next.
    Returns the new waveform id if OK, otherwise PI_EMPTY_WAVEFORM, PI_NO_WAVEFORM_ID, PI_TOO_MANY_CBS, or PI_TOO_MANY_OOL.

int wave_delete(int pi, unsigned wave_id)

    This function deletes the waveform with id wave_id.
             pi: >=0 (as returned by pigpio_start).
        wave_id: >=0, as returned by wave_create.
    Wave ids are allocated in order, 0, 1, 2, etc.
    The wave is flagged for deletion. The resources used by the wave will only be reused when either of the following apply.
    - all waves with higher numbered wave ids have been deleted or have been flagged for deletion.
    - a new wave is created which uses exactly the same resources as the current wave (see the C source for gpioWaveCreate for details).
    Returns 0 if OK, otherwise PI_BAD_WAVE_ID.

int wave_send_once(int pi, unsigned wave_id)

    This function transmits the waveform with id wave_id. The waveform is sent once.
    NOTE: Any hardware PWM started by hardware_PWM will be cancelled.
             pi: >=0 (as returned by pigpio_start).
        wave_id: >=0, as returned by wave_create.
    Returns the number of DMA control blocks in the waveform if OK, otherwise PI_BAD_WAVE_ID, or PI_BAD_WAVE_MODE.

int wave_send_repeat(int pi, unsigned wave_id)

    This function transmits the waveform with id wave_id. The waveform cycles until cancelled (either by the sending of a new waveform or by wave_tx_stop).
    NOTE: Any hardware PWM started by hardware_PWM will be cancelled.
             pi: >=0 (as returned by pigpio_start).
        wave_id: >=0, as returned by wave_create.
    Returns the number of DMA control blocks in the waveform if OK, otherwise PI_BAD_WAVE_ID, or PI_BAD_WAVE_MODE.

int wave_send_using_mode(int pi, unsigned wave_id, unsigned mode)

    Transmits the waveform with id wave_id using mode mode.
             pi: >=0 (as returned by pigpio_start).
        wave_id: >=0, as returned by wave_create.
           mode: PI_WAVE_MODE_ONE_SHOT, PI_WAVE_MODE_REPEAT,
                 PI_WAVE_MODE_ONE_SHOT_SYNC, or PI_WAVE_MODE_REPEAT_SYNC.
    PI_WAVE_MODE_ONE_SHOT: same as wave_send_once.
    PI_WAVE_MODE_REPEAT same as wave_send_repeat.
    PI_WAVE_MODE_ONE_SHOT_SYNC same as wave_send_once but tries to sync with the previous waveform.
    PI_WAVE_MODE_REPEAT_SYNC same as wave_send_repeat but tries to sync with the previous waveform.
    WARNING: bad things may happen if you delete the previous waveform before it has been synced to the new waveform.
    NOTE: Any hardware PWM started by hardware_PWM will be cancelled.
    Returns the number of DMA control blocks in the waveform if OK, otherwise PI_BAD_WAVE_ID, or PI_BAD_WAVE_MODE.

int wave_chain(int pi, char *buf, unsigned bufSize)

    This function transmits a chain of waveforms.
    NOTE: Any hardware PWM started by hardware_PWM will be cancelled.
    The waves to be transmitted are specified by the contents of buf which contains an ordered list of wave_ids and optional command codes and related data.
             pi: >=0 (as returned by pigpio_start).
            buf: pointer to the wave_ids and optional command codes
        bufSize: the number of bytes in buf
    Returns 0 if OK, otherwise PI_CHAIN_NESTING, PI_CHAIN_LOOP_CNT, PI_BAD_CHAIN_LOOP, PI_BAD_CHAIN_CMD, PI_CHAIN_COUNTER, PI_BAD_CHAIN_DELAY, PI_CHAIN_TOO_BIG, or PI_BAD_WAVE_ID.
    Each wave is transmitted in the order specified. A wave may occur multiple times per chain.
    A blocks of waves may be transmitted multiple times by using the loop commands. The block is bracketed by loop start and end commands. Loops may be nested.
    Delays between waves may be added with the delay command.
    The following command codes are supported:
    Name Cmd & Data Meaning
    Loop Start 255 0 Identify start of a wave block
    Loop Repeat 255 1 x y loop x + y*256 times
    Delay 255 2 x y delay x + y*256 microseconds
    Loop Forever 255 3 loop forever
    If present Loop Forever must be the last entry in the chain.
    The code is currently dimensioned to support a chain with roughly 600 entries and 20 loop counters.
    Example
        #include <stdio.h>
        #include <pigpiod_if2.h>
        #define WAVES 5
        #define GPIO 4
        int main(int argc, char *argv[])
        {
           int i, pi, wid[WAVES];
           pi = pigpio_start(0, 0);
           if (pi<0) return -1;
           set_mode(pi, GPIO, PI_OUTPUT);
           for (i=0; i<WAVES; i++)
           {
              wave_add_generic(pi, 2, (gpioPulse_t[])
                 {{1<<GPIO, 0,        20},
                  {0, 1<<GPIO, (i+1)*200}});
              wid[i] = wave_create(pi);
           }
           wave_chain(pi, (char []) {
              wid[4], wid[3], wid[2],       // transmit waves 4+3+2
              255, 0,                       // loop start
                 wid[0], wid[0], wid[0],    // transmit waves 0+0+0
                 255, 0,                    // loop start
                    wid[0], wid[1],         // transmit waves 0+1
                    255, 2, 0x88, 0x13,     // delay 5000us
                 255, 1, 30, 0,             // loop end (repeat 30 times)
                 255, 0,                    // loop start
                    wid[2], wid[3], wid[0], // transmit waves 2+3+0
                    wid[3], wid[1], wid[2], // transmit waves 3+1+2
                 255, 1, 10, 0,             // loop end (repeat 10 times)
              255, 1, 5, 0,                 // loop end (repeat 5 times)
              wid[4], wid[4], wid[4],       // transmit waves 4+4+4
              255, 2, 0x20, 0x4E,           // delay 20000us
              wid[0], wid[0], wid[0],       // transmit waves 0+0+0
              }, 46);
           while (wave_tx_busy(pi)) time_sleep(0.1);
           for (i=0; i<WAVES; i++) wave_delete(pi, wid[i]);
           pigpio_stop(pi);
        }

int wave_tx_at(int pi)

    This function returns the id of the waveform currently being transmitted.
        pi: >=0 (as returned by pigpio_start).
    Returns the waveform id or one of the following special values:
    PI_WAVE_NOT_FOUND (9998) - transmitted wave not found.
    PI_NO_TX_WAVE (9999) - no wave being transmitted.

int wave_tx_busy(int pi)

    This function checks to see if a waveform is currently being transmitted.
        pi: >=0 (as returned by pigpio_start).
    Returns 1 if a waveform is currently being transmitted, otherwise 0.

int wave_tx_stop(int pi)

    This function stops the transmission of the current waveform.
        pi: >=0 (as returned by pigpio_start).
    Returns 0 if OK.
    This function is intended to stop a waveform started with the repeat mode.

int wave_get_micros(int pi)

    This function returns the length in microseconds of the current waveform.
        pi: >=0 (as returned by pigpio_start).

int wave_get_high_micros(int pi)

    This function returns the length in microseconds of the longest waveform created since the pigpio daemon was started.
        pi: >=0 (as returned by pigpio_start).

int wave_get_max_micros(int pi)

    This function returns the maximum possible size of a waveform in
    microseconds.
        pi: >=0 (as returned by pigpio_start).

int wave_get_pulses(int pi)

    This function returns the length in pulses of the current waveform.
        pi: >=0 (as returned by pigpio_start).

int wave_get_high_pulses(int pi)

    This function returns the length in pulses of the longest waveform created since the pigpio daemon was started.
        pi: >=0 (as returned by pigpio_start).

int wave_get_max_pulses(int pi)

    This function returns the maximum possible size of a waveform in pulses.
        pi: >=0 (as returned by pigpio_start).

int wave_get_cbs(int pi)

    This function returns the length in DMA control blocks of the current waveform.
        pi: >=0 (as returned by pigpio_start).

int wave_get_high_cbs(int pi)

    This function returns the length in DMA control blocks of the longest waveform created since the pigpio daemon was started.
        pi: >=0 (as returned by pigpio_start).

int wave_get_max_cbs(int pi)

    This function returns the maximum possible size of a waveform in DMA control blocks.
        pi: >=0 (as returned by pigpio_start).

int gpio_trigger(int pi, unsigned user_gpio, unsigned pulseLen, unsigned level)

    This function sends a trigger pulse to a GPIO. The GPIO is set to level for pulseLen microseconds and then reset to not level.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
         pulseLen: 1-100.
            level: 0,1.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_LEVEL, PI_BAD_PULSELEN, or PI_NOT_PERMITTED.

int store_script(int pi, char *script)

    This function stores a script for later execution.
    See http://abyz.me.uk/rpi/pigpio/pigs.html#Scripts for details.
            pi: >=0 (as returned by pigpio_start).
        script: the text of the script.
    The function returns a script id if the script is valid, otherwise PI_BAD_SCRIPT.

int run_script(int pi, unsigned script_id, unsigned numPar, uint32_t *param)

    This function runs a stored script.
               pi: >=0 (as returned by pigpio_start).
        script_id: >=0, as returned by store_script.
           numPar: 0-10, the number of parameters.
            param: an array of parameters.
    The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID, or PI_TOO_MANY_PARAM
    param is an array of up to 10 parameters which may be referenced in the script as p0 to p9.

int update_script(int pi, unsigned script_id, unsigned numPar, uint32_t *param)

    This function sets the parameters of a script. The script may or may not be running. The first numPar parameters of the script are overwritten with the new values.
               pi: >=0 (as returned by pigpio_start).
        script_id: >=0, as returned by store_script.
           numPar: 0-10, the number of parameters.
            param: an array of parameters.
    The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID, or PI_TOO_MANY_PARAM.
    param is an array of up to 10 parameters which may be referenced in the script as p0 to p9.

int script_status(int pi, unsigned script_id, uint32_t *param)

    This function returns the run status of a stored script as well as the current values of parameters 0 to 9.
               pi: >=0 (as returned by pigpio_start).
        script_id: >=0, as returned by store_script.
            param: an array to hold the returned 10 parameters.
    The function returns greater than or equal to 0 if OK, otherwise PI_BAD_SCRIPT_ID.
    The run status may be
        PI_SCRIPT_INITING
        PI_SCRIPT_HALTED
        PI_SCRIPT_RUNNING
        PI_SCRIPT_WAITING
        PI_SCRIPT_FAILED
    The current value of script parameters 0 to 9 are returned in param.

int stop_script(int pi, unsigned script_id)

    This function stops a running script.
               pi: >=0 (as returned by pigpio_start).
        script_id: >=0, as returned by store_script.
    The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID.

int delete_script(int pi, unsigned script_id)

    This function deletes a stored script.
               pi: >=0 (as returned by pigpio_start).
        script_id: >=0, as returned by store_script.
    The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID.

int bb_serial_read_open(int pi, unsigned user_gpio, unsigned baud, unsigned data_bits)

    This function opens a GPIO for bit bang reading of serial data.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
             baud: 50-250000
        data_bits: 1-32
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_WAVE_BAUD, or PI_GPIO_IN_USE.
    The serial data is returned in a cyclic buffer and is read using bb_serial_read.
    It is the caller's responsibility to read data from the cyclic buffer in a timely fashion.

int bb_serial_read(int pi, unsigned user_gpio, void *buf, size_t bufSize)

    This function copies up to bufSize bytes of data read from the bit bang serial cyclic buffer to the buffer starting at buf.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31, previously opened with bb_serial_read_open.
              buf: an array to receive the read bytes.
          bufSize: >=0
    Returns the number of bytes copied if OK, otherwise PI_BAD_USER_GPIO or PI_NOT_SERIAL_GPIO.
    The bytes returned for each character depend upon the number of data bits data_bits specified in the bb_serial_read_open command.
    For data_bits 1-8 there will be one byte per character.
    For data_bits 9-16 there will be two bytes per character.
    For data_bits 17-32 there will be four bytes per character.

int bb_serial_read_close(int pi, unsigned user_gpio)

    This function closes a GPIO for bit bang reading of serial data.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31, previously opened with bb_serial_read_open.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, or PI_NOT_SERIAL_GPIO.

int bb_serial_invert(int pi, unsigned user_gpio, unsigned invert)

    This function inverts serial logic for big bang serial reads.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31, previously opened with bb_serial_read_open.
           invert: 0-1, 1 invert, 0 normal.
    Returns 0 if OK, otherwise PI_NOT_SERIAL_GPIO or PI_BAD_SER_INVERT.

int i2c_open(int pi, unsigned i2c_bus, unsigned i2c_addr, unsigned i2c_flags)

    This returns a handle for the device at address i2c_addr on bus i2c_bus.
               pi: >=0 (as returned by pigpio_start).
          i2c_bus: >=0.
         i2c_addr: 0-0x7F.
        i2c_flags: 0.
    No flags are currently defined. This parameter should be set to zero.
    Physically buses 0 and 1 are available on the Pi. Higher numbered buses will be available if a kernel supported bus multiplexor is being used.
    The GPIO used are given in the following table.
            SDA SCL
    I2C 0 0 1
    I2C 1 2 3
    Returns a handle (>=0) if OK, otherwise PI_BAD_I2C_BUS, PI_BAD_I2C_ADDR, PI_BAD_FLAGS, PI_NO_HANDLE, or PI_I2C_OPEN_FAILED.
    For the SMBus commands the low level transactions are shown at the end of the function description. The following abbreviations are used.
        S       (1 bit) : Start bit
        P       (1 bit) : Stop bit
        Rd/Wr   (1 bit) : Read/Write bit. Rd equals 1, Wr equals 0.
        A, NA   (1 bit) : Accept and not accept bit.
        Addr    (7 bits): I2C 7 bit address.
        i2c_reg (8 bits): A byte which often selects a register.
        Data    (8 bits): A data byte.
        Count   (8 bits): A byte defining the length of a block operation.
        [..]: Data sent by the device.

int i2c_close(int pi, unsigned handle)

    This closes the I2C device associated with the handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
    Returns 0 if OK, otherwise PI_BAD_HANDLE.

int i2c_write_quick(int pi, unsigned handle, unsigned bit)

    This sends a single bit (in the Rd/Wr bit) to the device associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
           bit: 0-1, the value to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
    Quick command. SMBus 2.0 5.5.1
        S Addr bit [A] P

int i2c_write_byte(int pi, unsigned handle, unsigned bVal)

    This sends a single byte to the device associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
          bVal: 0-0xFF, the value to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
    Send byte. SMBus 2.0 5.5.2
        S Addr Wr [A] bVal [A] P

int i2c_read_byte(int pi, unsigned handle)

    This reads a single byte from the device associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
    Returns the byte read (>=0) if OK, otherwise PI_BAD_HANDLE, or PI_I2C_READ_FAILED.
    Receive byte. SMBus 2.0 5.5.3
        S Addr Rd [A] [Data] NA P

int i2c_write_byte_data(int pi, unsigned handle, unsigned i2c_reg, unsigned bVal)

    This writes a single byte to the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write.
           bVal: 0-0xFF, the value to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
    Write byte. SMBus 2.0 5.5.4
        S Addr Wr [A] i2c_reg [A] bVal [A] P

int i2c_write_word_data(int pi, unsigned handle, unsigned i2c_reg, unsigned wVal)

    This writes a single 16 bit word to the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write.
           wVal: 0-0xFFFF, the value to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
    Write word. SMBus 2.0 5.5.4
        S Addr Wr [A] i2c_reg [A] wval_Low [A] wVal_High [A] P

int i2c_read_byte_data(int pi, unsigned handle, unsigned i2c_reg)

    This reads a single byte from the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to read.
    Returns the byte read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
    Read byte. SMBus 2.0 5.5.5
        S Addr Wr [A] i2c_reg [A] S Addr Rd [A] [Data] NA P

int i2c_read_word_data(int pi, unsigned handle, unsigned i2c_reg)

    This reads a single 16 bit word from the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to read.
    Returns the word read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
    Read word. SMBus 2.0 5.5.5
        S Addr Wr [A] i2c_reg [A]
           S Addr Rd [A] [DataLow] A [DataHigh] NA P

int i2c_process_call(int pi, unsigned handle, unsigned i2c_reg, unsigned wVal)

    This writes 16 bits of data to the specified register of the device associated with handle and and reads 16 bits of data in return.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write/read.
           wVal: 0-0xFFFF, the value to write.
    Returns the word read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
    Process call. SMBus 2.0 5.5.6
        S Addr Wr [A] i2c_reg [A] wVal_Low [A] wVal_High [A]
           S Addr Rd [A] [DataLow] A [DataHigh] NA P

int i2c_write_block_data(int pi, unsigned handle, unsigned i2c_reg, char *buf, unsigned count)

    This writes up to 32 bytes to the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write.
            buf: an array with the data to send.
          count: 1-32, the number of bytes to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
    Block write. SMBus 2.0 5.5.7
        S Addr Wr [A] i2c_reg [A] count [A] buf0 [A] buf1 [A] ...
           [A] bufn [A] P

int i2c_read_block_data(int pi, unsigned handle, unsigned i2c_reg, char *buf)

    This reads a block of up to 32 bytes from the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to read.
            buf: an array to receive the read data.
    The amount of returned data is set by the device.
    Returns the number of bytes read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
    Block read. SMBus 2.0 5.5.7
        S Addr Wr [A] i2c_reg [A]
           S Addr Rd [A] [Count] A [buf0] A [buf1] A ... A [bufn] NA P

int i2c_block_process_call(int pi, unsigned handle, unsigned i2c_reg, char *buf, unsigned count)

    This writes data bytes to the specified register of the device associated with handle and reads a device specified number of bytes of data in return.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write/read.
            buf: an array with the data to send and to receive the read data.
          count: 1-32, the number of bytes to write.
    Returns the number of bytes read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
    The smbus 2.0 documentation states that a minimum of 1 byte may be sent and a minimum of 1 byte may be received. The total number of bytes sent/received must be 32 or less.
    Block write-block read. SMBus 2.0 5.5.8
        S Addr Wr [A] i2c_reg [A] count [A] buf0 [A] ...
           S Addr Rd [A] [Count] A [Data] ... A P

int i2c_read_i2c_block_data(int pi, unsigned handle, unsigned i2c_reg, char *buf, unsigned count)

    This reads count bytes from the specified register of the device associated with handle . The count may be 1-32.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to read.
            buf: an array to receive the read data.
          count: 1-32, the number of bytes to read.
    Returns the number of bytes read (>0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
        S Addr Wr [A] i2c_reg [A]
           S Addr Rd [A] [buf0] A [buf1] A ... A [bufn] NA P

int i2c_write_i2c_block_data(int pi, unsigned handle, unsigned i2c_reg, char *buf, unsigned count)

    This writes 1 to 32 bytes to the specified register of the device associated with handle.
             pi: >=0 (as returned by pigpio_start).
         handle: >=0, as returned by a call to i2c_open.
        i2c_reg: 0-255, the register to write.
            buf: the data to write.
          count: 1-32, the number of bytes to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
        S Addr Wr [A] i2c_reg [A] buf0 [A] buf1 [A] ... [A] bufn [A] P

int i2c_read_device(int pi, unsigned handle, char *buf, unsigned count)

    This reads count bytes from the raw device into buf.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
           buf: an array to receive the read data bytes.
         count: >0, the number of bytes to read.
    Returns count (>0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_READ_FAILED.
        S Addr Rd [A] [buf0] A [buf1] A ... A [bufn] NA P

int i2c_write_device(int pi, unsigned handle, char *buf, unsigned count)

    This writes count bytes from buf to the raw device.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2c_open.
           buf: an array containing the data bytes to write.
         count: >0, the number of bytes to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_I2C_WRITE_FAILED.
        S Addr Wr [A] buf0 [A] buf1 [A] ... [A] bufn [A] P

int i2c_zip(int pi, unsigned handle, char *inBuf, unsigned inLen, char *outBuf, unsigned outLen)

    This function executes a sequence of I2C operations. The operations to be performed are specified by the contents of inBuf which contains the concatenated command codes and associated data.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to i2cOpen
         inBuf: pointer to the concatenated I2C commands, see below
         inLen: size of command buffer
        outBuf: pointer to buffer to hold returned data
        outLen: size of output buffer
    Returns >= 0 if OK (the number of bytes read), otherwise PI_BAD_HANDLE, PI_BAD_POINTER, PI_BAD_I2C_CMD, PI_BAD_I2C_RLEN. PI_BAD_I2C_WLEN, or PI_BAD_I2C_SEG.
    The following command codes are supported:
    Name Cmd & Data Meaning
    End 0 No more commands
    Escape 1 Next P is two bytes
    On 2 Switch combined flag on
    Off 3 Switch combined flag off
    Address 4 P Set I2C address to P
    Flags 5 lsb msb Set I2C flags to lsb + (msb << 8)
    Read 6 P Read P bytes of data
    Write 7 P ... Write P bytes of data
    The address, read, and write commands take a parameter P. Normally P is one byte (0-255). If the command is preceded by the Escape command then P is two bytes (0-65535, least significant byte first).
    The address defaults to that associated with the handle. The flags default to 0. The address and flags maintain their previous value until updated.
    The returned I2C data is stored in consecutive locations of outBuf.
    Example
        Set address 0x53, write 0x32, read 6 bytes
        Set address 0x1E, write 0x03, read 6 bytes
        Set address 0x68, write 0x1B, read 8 bytes
        End
        0x04 0x53   0x07 0x01 0x32   0x06 0x06
        0x04 0x1E   0x07 0x01 0x03   0x06 0x06
        0x04 0x68   0x07 0x01 0x1B   0x06 0x08
        0x00

int bb_i2c_open(int pi, unsigned SDA, unsigned SCL, unsigned baud)

    This function selects a pair of GPIO for bit banging I2C at a specified baud rate.
    Bit banging I2C allows for certain operations which are not possible with the standard I2C driver.
    o baud rates as low as 50
    o repeated starts
    o clock stretching
    o I2C on any pair of spare GPIO
          pi: >=0 (as returned by pigpio_start).
         SDA: 0-31
         SCL: 0-31
        baud: 50-500000
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_I2C_BAUD, or PI_GPIO_IN_USE.
    NOTE:
    The GPIO used for SDA and SCL must have pull-ups to 3V3 connected. As a guide the hardware pull-ups on pins 3 and 5 are 1k8 in value.

int bb_i2c_close(int pi, unsigned SDA)

    This function stops bit banging I2C on a pair of GPIO previously opened with bb_i2c_open.
         pi: >=0 (as returned by pigpio_start).
        SDA: 0-31, the SDA GPIO used in a prior call to bb_i2c_open
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, or PI_NOT_I2C_GPIO.

int bb_i2c_zip(int pi, unsigned SDA, char *inBuf, unsigned inLen, char *outBuf, unsigned outLen)

    This function executes a sequence of bit banged I2C operations. The operations to be performed are specified by the contents of inBuf which contains the concatenated command codes and associated data.
            pi: >=0 (as returned by pigpio_start).
           SDA: 0-31 (as used in a prior call to bb_i2c_open)
         inBuf: pointer to the concatenated I2C commands, see below
         inLen: size of command buffer
        outBuf: pointer to buffer to hold returned data
        outLen: size of output buffer
    Returns >= 0 if OK (the number of bytes read), otherwise PI_BAD_USER_GPIO, PI_NOT_I2C_GPIO, PI_BAD_POINTER, PI_BAD_I2C_CMD, PI_BAD_I2C_RLEN, PI_BAD_I2C_WLEN, PI_I2C_READ_FAILED, or PI_I2C_WRITE_FAILED.
    The following command codes are supported:
    Name Cmd & Data Meaning
    End 0 No more commands
    Escape 1 Next P is two bytes
    Start 2 Start condition
    Stop 3 Stop condition
    Address 4 P Set I2C address to P
    Flags 5 lsb msb Set I2C flags to lsb + (msb << 8)
    Read 6 P Read P bytes of data
    Write 7 P ... Write P bytes of data
    The address, read, and write commands take a parameter P. Normally P is one byte (0-255). If the command is preceded by the Escape command then P is two bytes (0-65535, least significant byte first).
    The address and flags default to 0. The address and flags maintain their previous value until updated.
    No flags are currently defined.
    The returned I2C data is stored in consecutive locations of outBuf.
    Example
        Set address 0x53
        start, write 0x32, (re)start, read 6 bytes, stop
        Set address 0x1E
        start, write 0x03, (re)start, read 6 bytes, stop
        Set address 0x68
        start, write 0x1B, (re)start, read 8 bytes, stop
        End
        0x04 0x53
        0x02 0x07 0x01 0x32   0x02 0x06 0x06 0x03
        0x04 0x1E
        0x02 0x07 0x01 0x03   0x02 0x06 0x06 0x03
        0x04 0x68
        0x02 0x07 0x01 0x1B   0x02 0x06 0x08 0x03
        0x00

int bb_spi_open(int pi, unsigned CS, unsigned MISO, unsigned MOSI, unsigned SCLK, unsigned baud, unsigned spi_flags)

    This function selects a set of GPIO for bit banging SPI at a specified baud rate.
               pi: >=0 (as returned by pigpio_start).
               CS: 0-31
             MISO: 0-31
             MOSI: 0-31
             SCLK: 0-31
             baud: 50-250000
        spi_flags: see below
    spi_flags consists of the least significant 22 bits.
        21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
         0  0  0  0  0  0  R  T  0  0  0  0  0  0  0  0  0  0  0  p  m  m
    mm defines the SPI mode, defaults to 0
        Mode CPOL CPHA
         0    0    0
         1    0    1
         2    1    0
         3    1    1
    p is 0 if CS is active low (default) and 1 for active high.
    T is 1 if the least significant bit is transmitted on MOSI first, the default (0) shifts the most significant bit out first.
    R is 1 if the least significant bit is received on MISO first, the default (0) receives the most significant bit first.
    The other bits in flags should be set to zero.
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, PI_BAD_SPI_BAUD, or PI_GPIO_IN_USE.
    If more than one device is connected to the SPI bus (defined by SCLK, MOSI, and MISO) each must have its own CS.
    Example
        bb_spi_open(pi,10, MISO, MOSI, SCLK, 10000, 0); // device 1
        bb_spi_open(pi,11, MISO, MOSI, SCLK, 20000, 3); // device 2

int bb_spi_close(int pi, unsigned CS)

    This function stops bit banging SPI on a set of GPIO opened with bbSPIOpen.
        pi: >=0 (as returned by pigpio_start).
        CS: 0-31, the CS GPIO used in a prior call to bb_spi_open
    Returns 0 if OK, otherwise PI_BAD_USER_GPIO, or PI_NOT_SPI_GPIO.

int bb_spi_xfer(int pi, unsigned CS, char *txBuf, char *rxBuf, unsigned count)

    This function executes a bit banged SPI transfer.
           pi: >=0 (as returned by pigpio_start).
           CS: 0-31 (as used in a prior call to bb_spi_open)
        txBuf: pointer to buffer to hold data to be sent
        rxBuf: pointer to buffer to hold returned data
        count: size of data transfer
    Returns >= 0 if OK (the number of bytes read), otherwise PI_BAD_USER_GPIO, PI_NOT_SPI_GPIO or PI_BAD_POINTER.
    Example
        // gcc -Wall -pthread -o bb_spi_x_test bb_spi_x_test.c -lpigpiod_if2
        // ./bb_spi_x_test
        #include <stdio.h>
        #include "pigpiod_if2.h"
        #define CE0 5
        #define CE1 6
        #define MISO 13
        #define MOSI 19
        #define SCLK 12
        int main(int argc, char *argv[])
        {
           int i, pi, count, set_val, read_val;
           unsigned char inBuf[3];
           char cmd1[] = {0, 0};
           char cmd2[] = {12, 0};
           char cmd3[] = {1, 128, 0};
           if ((pi = pigpio_start(0, 0)) < 0)
           {
              fprintf(stderr, "pigpio initialisation failed (%d)., pi);
              return 1;
           }
           bb_spi_open(pi, CE0, MISO, MOSI, SCLK, 10000, 0); // MCP4251 DAC
           bb_spi_open(pi, CE1, MISO, MOSI, SCLK, 20000, 3); // MCP3008 ADC
           for (i=0; i<256; i++)
           {
              cmd1[1] = i;
              count = bb_spi_xfer(pi, CE0, cmd1, (char *)inBuf, 2); // > DAC
              if (count == 2)
              {
                 count = bb_spi_xfer(pi, CE0, cmd2, (char *)inBuf, 2); // < DAC
                 if (count == 2)
                 {
                    set_val = inBuf[1];
                    count = bb_spi_xfer(pi, CE1, cmd3, (char *)inBuf, 3); // < ADC
                    if (count == 3)
                    {
                       read_val = ((inBuf[1]&3)<<8) | inBuf[2];
                       printf("%d %d, set_val, read_val);
                    }
                 }
              }
           }
           bb_spi_close(pi, CE0);
           bb_spi_close(pi, CE1);
           pigpio_stop(pi);
        }

int spi_open(int pi, unsigned spi_channel, unsigned baud, unsigned spi_flags)

    This function returns a handle for the SPI device on the channel. Data will be transferred at baud bits per second. The flags may be used to modify the default behaviour of 4-wire operation, mode 0, active low chip select.
    The Pi has two SPI peripherals: main and auxiliary.
    The main SPI has two chip selects (channels), the auxiliary has three.
    The auxiliary SPI is available on all models but the A and B.
    The GPIO used are given in the following table.
               MISO MOSI SCLK CE0 CE1 CE2
    Main SPI 9 10 11 8 7 -
    Aux SPI 19 20 21 18 17 16
                 pi: >=0 (as returned by pigpio_start).
        spi_channel: 0-1 (0-2 for the auxiliary SPI).
               baud: 32K-125M (values above 30M are unlikely to work).
          spi_flags: see below.
    Returns a handle (>=0) if OK, otherwise PI_BAD_SPI_CHANNEL, PI_BAD_SPI_SPEED, PI_BAD_FLAGS, PI_NO_AUX_SPI, or PI_SPI_OPEN_FAILED.
    spi_flags consists of the least significant 22 bits.
        21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
         b  b  b  b  b  b  R  T  n  n  n  n  W  A u2 u1 u0 p2 p1 p0  m  m
    mm defines the SPI mode.
    Warning: modes 1 and 3 do not appear to work on the auxiliary SPI.
        Mode POL PHA
         0    0   0
         1    0   1
         2    1   0
         3    1   1
    px is 0 if CEx is active low (default) and 1 for active high.
    ux is 0 if the CEx GPIO is reserved for SPI (default) and 1 otherwise.
    A is 0 for the main SPI, 1 for the auxiliary SPI.
    W is 0 if the device is not 3-wire, 1 if the device is 3-wire. Main SPI only.
    nnnn defines the number of bytes (0-15) to write before switching the MOSI line to MISO to read data. This field is ignored if W is not set. Main SPI only.
    T is 1 if the least significant bit is transmitted on MOSI first, the default (0) shifts the most significant bit out first. Auxiliary SPI only.
    R is 1 if the least significant bit is received on MISO first, the default (0) receives the most significant bit first. Auxiliary SPI only.
    bbbbbb defines the word size in bits (0-32). The default (0) sets 8 bits per word. Auxiliary SPI only.
    The spi_read, spi_write, and spi_xfer functions transfer data packed into 1, 2, or 4 bytes according to the word size in bits.
    For bits 1-8 there will be one byte per character.
    For bits 9-16 there will be two bytes per character.
    For bits 17-32 there will be four bytes per character.
    Multi-byte transfers are made in least significant byte first order.
    E.g. to transfer 32 11-bit words buf should contain 64 bytes and count should be 64.
    E.g. to transfer the 14 bit value 0x1ABC send the bytes 0xBC followed by 0x1A.
    The other bits in flags should be set to zero.

int spi_close(int pi, unsigned handle)

    This functions closes the SPI device identified by the handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to spi_open.
    Returns 0 if OK, otherwise PI_BAD_HANDLE.

int spi_read(int pi, unsigned handle, char *buf, unsigned count)

    This function reads count bytes of data from the SPI device associated with the handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to spi_open.
           buf: an array to receive the read data bytes.
         count: the number of bytes to read.
    Returns the number of bytes transferred if OK, otherwise PI_BAD_HANDLE, PI_BAD_SPI_COUNT, or PI_SPI_XFER_FAILED.

int spi_write(int pi, unsigned handle, char *buf, unsigned count)

    This function writes count bytes of data from buf to the SPI device associated with the handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to spi_open.
           buf: the data bytes to write.
         count: the number of bytes to write.
    Returns the number of bytes transferred if OK, otherwise PI_BAD_HANDLE, PI_BAD_SPI_COUNT, or PI_SPI_XFER_FAILED.

int spi_xfer(int pi, unsigned handle, char *txBuf, char *rxBuf, unsigned count)

    This function transfers count bytes of data from txBuf to the SPI device associated with the handle. Simultaneously count bytes of data are read from the device and placed in rxBuf.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to spi_open.
         txBuf: the data bytes to write.
         rxBuf: the received data bytes.
         count: the number of bytes to transfer.
    Returns the number of bytes transferred if OK, otherwise PI_BAD_HANDLE, PI_BAD_SPI_COUNT, or PI_SPI_XFER_FAILED.

int serial_open(int pi, char *ser_tty, unsigned baud, unsigned ser_flags)

    This function opens a serial device at a specified baud rate with specified flags. The device name must start with /dev/tty or /dev/serial.
               pi: >=0 (as returned by pigpio_start).
          ser_tty: the serial device to open.
             baud: the baud rate in bits per second, see below.
        ser_flags: 0.
    Returns a handle (>=0) if OK, otherwise PI_NO_HANDLE, or PI_SER_OPEN_FAILED.
    The baud rate must be one of 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200, or 230400.
    No flags are currently defined. This parameter should be set to zero.

int serial_close(int pi, unsigned handle)

    This function closes the serial device associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
    Returns 0 if OK, otherwise PI_BAD_HANDLE.

int serial_write_byte(int pi, unsigned handle, unsigned bVal)

    This function writes bVal to the serial port associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_SER_WRITE_FAILED.

int serial_read_byte(int pi, unsigned handle)

    This function reads a byte from the serial port associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
    Returns the read byte (>=0) if OK, otherwise PI_BAD_HANDLE, PI_SER_READ_NO_DATA, or PI_SER_READ_FAILED.
    If no data is ready PI_SER_READ_NO_DATA is returned.

int serial_write(int pi, unsigned handle, char *buf, unsigned count)

    This function writes count bytes from buf to the the serial port associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
           buf: the array of bytes to write.
         count: the number of bytes to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, or PI_SER_WRITE_FAILED.

int serial_read(int pi, unsigned handle, char *buf, unsigned count)

    This function reads up to count bytes from the the serial port associated with handle and writes them to buf.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
           buf: an array to receive the read data.
         count: the maximum number of bytes to read.
    Returns the number of bytes read (>=0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, PI_SER_READ_NO_DATA, or PI_SER_WRITE_FAILED.
    If no data is ready zero is returned.

int serial_data_available(int pi, unsigned handle)

    Returns the number of bytes available to be read from the device associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0, as returned by a call to serial_open.
    Returns the number of bytes of data available (>=0) if OK, otherwise PI_BAD_HANDLE.

int custom_1(int pi, unsigned arg1, unsigned arg2, char *argx, unsigned argc)

    This function is available for user customisation.
    It returns a single integer value.
          pi: >=0 (as returned by pigpio_start).
        arg1: >=0
        arg2: >=0
        argx: extra (byte) arguments
        argc: number of extra arguments
    Returns >= 0 if OK, less than 0 indicates a user defined error.

int custom_2(int pi, unsigned arg1, char *argx, unsigned argc, char *retBuf, unsigned retMax)

    This function is available for user customisation.
    It differs from custom_1 in that it returns an array of bytes rather than just an integer.
    The return value is an integer indicating the number of returned bytes.
            pi: >=0 (as returned by pigpio_start).
          arg1: >=0
          argc: extra (byte) arguments
         count: number of extra arguments
        retBuf: buffer for returned data
        retMax: maximum number of bytes to return
    Returns >= 0 if OK, less than 0 indicates a user defined error.
    Note, the number of returned bytes will be retMax or less.

int get_pad_strength(int pi, unsigned pad)

    This function returns the pad drive strength in mA.
         pi: >=0 (as returned by pigpio_start).
        pad: 0-2, the pad to get.
    Returns the pad drive strength if OK, otherwise PI_BAD_PAD.
    Pad GPIO
    0 0-27
    1 28-45
    2 46-53
    Example
        strength = get_pad_strength(pi, 0); //  get pad 0 strength

int set_pad_strength(int pi, unsigned pad, unsigned padStrength)

    This function sets the pad drive strength in mA.
                 pi: >=0 (as returned by pigpio_start).
                pad: 0-2, the pad to set.
        padStrength: 1-16 mA.
    Returns 0 if OK, otherwise PI_BAD_PAD, or PI_BAD_STRENGTH.
    Pad GPIO
    0 0-27
    1 28-45
    2 46-53
    Example
        set_pad_strength(pi, 0, 10); // set pad 0 strength to 10 mA

int shell_(int pi, char *scriptName, char *scriptString)

    This function uses the system call to execute a shell script with the given string as its parameter.
                  pi: >=0 (as returned by pigpio_start).
          scriptName: the name of the script, only alphanumeric characters,
                      '-' and '_' are allowed in the name.
        scriptString: the string to pass to the script.
    The exit status of the system call is returned if OK, otherwise PI_BAD_SHELL_STATUS.
    scriptName must exist in /opt/pigpio/cgi and must be executable.
    The returned exit status is normally 256 times that set by the shell script exit function. If the script can't be found 32512 will be returned.
    The following table gives some example returned statuses.
    Script exit status Returned system call status
    1 256
    5 1280
    10 2560
    200 51200
    script not found 32512
    Example
        // pass two parameters, hello and world
        status = shell_(pi, "scr1", "hello world");
        // pass three parameters, hello, string with spaces, and world
        status = shell_(pi, "scr1", "hello 'string with spaces' world");
        // pass one parameter, hello string with spaces world
        status = shell_(pi, "scr1", "

int file_open(int pi, char *file, unsigned mode)

    This function returns a handle to a file opened in a specified mode.
          pi: >=0 (as returned by pigpio_start).
        file: the file to open.
        mode: the file open mode.
    Returns a handle (>=0) if OK, otherwise PI_NO_HANDLE, PI_NO_FILE_ACCESS, PI_BAD_FILE_MODE, PI_FILE_OPEN_FAILED, or PI_FILE_IS_A_DIR.
    File
    A file may only be opened if permission is granted by an entry in /opt/pigpio/access. This is intended to allow remote access to files in a more or less controlled manner.
    Each entry in /opt/pigpio/access takes the form of a file path which may contain wildcards followed by a single letter permission. The permission may be R for read, W for write, U for read/write, and N for no access.
    Where more than one entry matches a file the most specific rule applies. If no entry matches a file then access is denied.
    Suppose /opt/pigpio/access contains the following entries
        /home/* n
        /home/pi/shared/dir_1/* w
        /home/pi/shared/dir_2/* r
        /home/pi/shared/dir_3/* u
        /home/pi/shared/dir_1/file.txt n
    Files may be written in directory dir_1 with the exception of file.txt.
    Files may be read in directory dir_2.
    Files may be read and written in directory dir_3.
    If a directory allows read, write, or read/write access then files may be created in that directory.
    In an attempt to prevent risky permissions the following paths are ignored in /opt/pigpio/access.
        a path containing ..
        a path containing only wildcards (*?)
        a path containing less than two non-wildcard parts
    Mode
    The mode may have the following values.
    Macro Value Meaning
    PI_FILE_READ 1 open file for reading
    PI_FILE_WRITE 2 open file for writing
    PI_FILE_RW 3 open file for reading and writing
    The following values may be or'd into the mode.
    Macro Value Meaning
    PI_FILE_APPEND 4 Writes append data to the end of the file
    PI_FILE_CREATE 8 The file is created if it doesn't exist
    PI_FILE_TRUNC 16 The file is truncated
    Newly created files are owned by root with permissions owner read and write.
    Example
        #include <stdio.h>
        #include <pigpiod_if2.h>
        int main(int argc, char *argv[])
        {
           int pi, handle, c;
           char buf[60000];
           pi = pigpio_start(NULL, NULL);
           if (pi < 0) return 1;
           // assumes /opt/pigpio/access contains the following line
           // /ram/*.c r
           handle = file_open(pi, "/ram/pigpio.c", PI_FILE_READ);
           if (handle >= 0)
           {
              while ((c=file_read(pi, handle, buf, sizeof(buf)-1)))
              {
                 buf[c] = 0;
                 printf("%s", buf);
              }
              file_close(pi, handle);
           }
           pigpio_stop(pi);
        }

int file_close(int pi, unsigned handle)

    This function closes the file associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0 (as returned by file_open).
    Returns 0 if OK, otherwise PI_BAD_HANDLE.
    Example
        file_close(pi, handle);

int file_write(int pi, unsigned handle, char *buf, unsigned count)

    This function writes count bytes from buf to the the file associated with handle.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0 (as returned by file_open).
           buf: the array of bytes to write.
         count: the number of bytes to write.
    Returns 0 if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, PI_FILE_NOT_WOPEN, or PI_BAD_FILE_WRITE.
    Example
        if (file_write(pi, handle, buf, 100) == 0)
        {
           // file written okay
        }
        else
        {
           // error
        }

int file_read(int pi, unsigned handle, char *buf, unsigned count)

    This function reads up to count bytes from the the file associated with handle and writes them to buf.
            pi: >=0 (as returned by pigpio_start).
        handle: >=0 (as returned by file_open).
           buf: an array to receive the read data.
         count: the maximum number of bytes to read.
    Returns the number of bytes read (>0) if OK, otherwise PI_BAD_HANDLE, PI_BAD_PARAM, PI_FILE_NOT_ROPEN, or PI_BAD_FILE_WRITE.
    Example
           bytes = file_read(pi, handle, buf, sizeof(buf));
           if (bytes >= 0)
           {
              // process read data
           }

int file_seek(int pi, unsigned handle, int32_t seekOffset, int seekFrom)

    This function seeks to a position within the file associated with handle.
                pi: >=0 (as returned by pigpio_start).
            handle: >=0 (as returned by file_open).
        seekOffset: the number of bytes to move.  Positive offsets
                    move forward, negative offsets backwards.
          seekFrom: one of PI_FROM_START (0), PI_FROM_CURRENT (1),
                    or PI_FROM_END (2).
    Returns the new byte position within the file (>=0) if OK, otherwise PI_BAD_HANDLE, or PI_BAD_FILE_SEEK.
    Example
        file_seek(pi, handle, 123, PI_FROM_START); // Start plus 123
        size = file_seek(pi, handle, 0, PI_FROM_END); // End, return size
        pos = file_seek(pi, handle, 0, PI_FROM_CURRENT); // Current position

int file_list(int pi, char *fpat, char *buf, unsigned count)

    This function returns a list of files which match a pattern.
           pi: >=0 (as returned by pigpio_start).
         fpat: file pattern to match.
          buf: an array to receive the matching file names.
        count: the maximum number of bytes to read.
    Returns the number of returned bytes if OK, otherwise PI_NO_FILE_ACCESS, or PI_NO_FILE_MATCH.
    The pattern must match an entry in /opt/pigpio/access. The pattern may contain wildcards. See file_open.
    NOTE
    The returned value is not the number of files, it is the number of bytes in the buffer. The file names are separated by newline characters.
    Example
        #include <stdio.h>
        #include <pigpiod_if2.h>
        int main(int argc, char *argv[])
        {
           int pi, handle, c;
           char buf[60000];
           pi = pigpio_start(NULL, NULL);
           if (pi < 0) return 1;
           // assumes /opt/pigpio/access contains the following line
           // /ram/*.c r
           c = file_list(pi, "/ram/p*.c", buf, sizeof(buf));
           if (c >= 0)
           {
              buf[c] = 0;
              printf("%s", buf);
           }
           pigpio_stop(pi);
        }

int callback(int pi, unsigned user_gpio, unsigned edge, CBFunc_t f)

    This function initialises a new callback.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
             edge: RISING_EDGE, FALLING_EDGE, or EITHER_EDGE.
                f: the callback function.
    The function returns a callback id if OK, otherwise pigif_bad_malloc, pigif_duplicate_callback, or pigif_bad_callback.
    The callback is called with the GPIO, edge, and tick, whenever the GPIO has the identified edge.
        Parameter   Value    Meaning
        GPIO        0-31     The GPIO which has changed state
        edge        0-2      0 = change to low (a falling edge)
                             1 = change to high (a rising edge)
                             2 = no level change (a watchdog timeout)
        tick        32 bit   The number of microseconds since boot
                             WARNING: this wraps around from
                             4294967295 to 0 roughly every 72 minutes

int callback_ex(int pi, unsigned user_gpio, unsigned edge, CBFuncEx_t f, void *userdata)

    This function initialises a new callback.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
             edge: RISING_EDGE, FALLING_EDGE, or EITHER_EDGE.
                f: the callback function.
         userdata: a pointer to arbitrary user data.
    The function returns a callback id if OK, otherwise pigif_bad_malloc, pigif_duplicate_callback, or pigif_bad_callback.
    The callback is called with the GPIO, edge, tick, and the userdata pointer, whenever the GPIO has the identified edge.
        Parameter   Value    Meaning
        GPIO        0-31     The GPIO which has changed state
        edge        0-2      0 = change to low (a falling edge)
                             1 = change to high (a rising edge)
                             2 = no level change (a watchdog timeout)
        tick        32 bit   The number of microseconds since boot
                             WARNING: this wraps around from
                             4294967295 to 0 roughly every 72 minutes
        userdata    pointer  Pointer to an arbitrary object

int callback_cancel(unsigned callback_id)

    This function cancels a callback identified by its id.
        callback_id: >=0, as returned by a call to callback or callback_ex.
    The function returns 0 if OK, otherwise pigif_callback_not_found.

int wait_for_edge(int pi, unsigned user_gpio, unsigned edge, double timeout)

    This function waits for an edge on the GPIO for up to timeout seconds.
               pi: >=0 (as returned by pigpio_start).
        user_gpio: 0-31.
             edge: RISING_EDGE, FALLING_EDGE, or EITHER_EDGE.
          timeout: >=0.
    The function returns when the edge occurs or after the timeout.
    Do not use this function for precise timing purposes, the edge is only checked 20 times a second. Whenever you need to know the accurate time of GPIO events use a callback function.
    The function returns 1 if the edge occurred, otherwise 0.

int bsc_xfer(int pi, bsc_xfer_t *bscxfer)

    This function provides a low-level interface to the SPI/I2C Slave peripheral on the BCM chip.
    This peripheral allows the Pi to act as a hardware slave device on an I2C or SPI bus.
    This is not a bit bang version and as such is OS timing independent. The bus timing is handled directly by the chip.
    The output process is simple. You simply append data to the FIFO buffer on the chip. This works like a queue, you add data to the queue and the master removes it.
    This function is not available on the BCM2711 (e.g. as used in the Pi4B).
    I can't get SPI to work properly. I tried with a control word of 0x303 and swapped MISO and MOSI.
    The function sets the BSC mode, writes any data in the transmit buffer to the BSC transmit FIFO, and copies any data in the BSC receive FIFO to the receive buffer.
             pi: >=0 (as returned by pigpio_start).
        bscxfer: a structure defining the transfer.
        typedef struct
        {
           uint32_t control;          // Write
           int rxCnt;                 // Read only
           char rxBuf[BSC_FIFO_SIZE]; // Read only
           int txCnt;                 // Write
           char txBuf[BSC_FIFO_SIZE]; // Write
        } bsc_xfer_t;
    To start a transfer set control (see below), copy the bytes to be added to the transmit FIFO (if any) to txBuf and set txCnt to the number of copied bytes.
    Upon return rxCnt will be set to the number of received bytes placed in rxBuf.
    The returned function value is the status of the transfer (see below).
    If there was an error the status will be less than zero (and will contain the error code).
    The most significant word of the returned status contains the number of bytes actually copied from txBuf to the BSC transmit FIFO (may be less than requested if the FIFO already contained untransmitted data).
    Note that the control word sets the BSC mode. The BSC will stay in that mode until a different control word is sent.
    The BSC peripheral uses GPIO 18 (SDA) and 19 (SCL) in I2C mode and GPIO 18 (MOSI), 19 (SCLK), 20 (MISO), and 21 (CE) in SPI mode. You need to swap MISO/MOSI between master and slave.
    When a zero control word is received GPIO 18-21 will be reset to INPUT mode.
    control consists of the following bits.
        22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
         a  a  a  a  a  a  a  -  - IT HC TF IR RE TE BK EC ES PL PH I2 SP EN
    Bits 0-13 are copied unchanged to the BSC CR register. See pages 163-165 of the Broadcom peripherals document for full details.
    aaaaaaa defines the I2C slave address (only relevant in I2C mode)
    IT invert transmit status flags
    HC enable host control
    TF enable test FIFO
    IR invert receive status flags
    RE enable receive
    TE enable transmit
    BK abort operation and clear FIFOs
    EC send control register as first I2C byte
    ES send status register as first I2C byte
    PL set SPI polarity high
    PH set SPI phase high
    I2 enable I2C mode
    SP enable SPI mode
    EN enable BSC peripheral
    The returned status has the following format
        20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
         S  S  S  S  S  R  R  R  R  R  T  T  T  T  T RB TE RF TF RE TB
    Bits 0-15 are copied unchanged from the BSC FR register. See pages 165-166 of the Broadcom peripherals document for full details.
    SSSSS number of bytes successfully copied to transmit FIFO
    RRRRR number of bytes in receieve FIFO
    TTTTT number of bytes in transmit FIFO
    RB receive busy
    TE transmit FIFO empty
    RF receive FIFO full
    TF transmit FIFO full
    RE receive FIFO empty
    TB transmit busy
    The following example shows how to configure the BSC peripheral as an I2C slave with address 0x13 and send four bytes.
    Example
        bsc_xfer_t xfer;
        xfer.control = (0x13<<16) | 0x305;
        memcpy(xfer.txBuf, "ABCD", 4);
        xfer.txCnt = 4;
        status = bsc_xfer(pi, &xfer);
        if (status >= 0)
        {
           // process transfer
        }

int bsc_i2c(int pi, int i2c_addr, bsc_xfer_t *bscxfer)

    This function allows the Pi to act as a slave I2C device.
    This function is not available on the BCM2711 (e.g.as used in the Pi4B).
    The data bytes (if any) are written to the BSC transmit FIFO and the bytes in the BSC receive FIFO are returned.
              pi: >=0 (as returned by pigpio_start).
        i2c_addr: 0-0x7F.
         bscxfer: a structure defining the transfer.
        typedef struct
        {
           uint32_t control;          // N/A
           int rxCnt;                 // Read only
           char rxBuf[BSC_FIFO_SIZE]; // Read only
           int txCnt;                 // Write
           char txBuf[BSC_FIFO_SIZE]; // Write
        } bsc_xfer_t;
    txCnt is set to the number of bytes to be transmitted, possibly zero. The data itself should be copied to txBuf.
    Any received data will be written to rxBuf with rxCnt set.
    See bsc_xfer for details of the returned status value.
    If there was an error the status will be less than zero (and will contain the error code).
    Note that an i2c_address of 0 may be used to close the BSC device and reassign the used GPIO (18/19) as inputs.

int event_callback(int pi, unsigned event, evtCBFunc_t f)

    This function initialises an event callback.
           pi: >=0 (as returned by pigpio_start).
        event: 0-31.
            f: the callback function.
    The function returns a callback id if OK, otherwise pigif_bad_malloc, pigif_duplicate_callback, or pigif_bad_callback.
    The callback is called with the event id, and tick, whenever the event occurs.

int event_callback_ex(int pi, unsigned event, evtCBFuncEx_t f, void *userdata)

    This function initialises an event callback.
              pi: >=0 (as returned by pigpio_start).
           event: 0-31.
               f: the callback function.
        userdata: a pointer to arbitrary user data.
    The function returns a callback id if OK, otherwise pigif_bad_malloc, pigif_duplicate_callback, or pigif_bad_callback.
    The callback is called with the event id, the tick, and the userdata pointer whenever the event occurs.

int event_callback_cancel(unsigned callback_id)

    This function cancels an event callback identified by its id.
        callback_id: >=0, as returned by a call to event_callback or
        event_callback_ex.
    The function returns 0 if OK, otherwise pigif_callback_not_found.

int wait_for_event(int pi, unsigned event, double timeout)

    This function waits for an event for up to timeout seconds.
             pi: >=0 (as returned by pigpio_start).
          event: 0-31.
        timeout: >=0.
    The function returns when the event occurs or after the timeout.
    The function returns 1 if the event occurred, otherwise 0.

int event_trigger(int pi, unsigned event)

    This function signals the occurrence of an event.
           pi: >=0 (as returned by pigpio_start).
        event: 0-31.
    Returns 0 if OK, otherwise PI_BAD_EVENT_ID.
    An event is a signal used to inform one or more consumers to start an action. Each consumer which has registered an interest in the event (e.g. by calling event_callback) will be informed by a callback.
    One event, PI_EVENT_BSC (31) is predefined. This event is auto generated on BSC slave activity.
    The meaning of other events is arbitrary.
    Note that other than its id and its tick there is no data associated with an event.

PARAMETERS

active: 0-1000000
    The number of microseconds level changes are reported for once a noise filter has been triggered (by steady microseconds of a stable level).

*addrStr
    A string specifying the host or IP address of the Pi running the pigpio daemon. It may be NULL in which case localhost is used unless overridden by the PIGPIO_ADDR environment variable.

arg1
    An unsigned argument passed to a user customised function. Its meaning is defined by the customiser.

arg2
    An unsigned argument passed to a user customised function. Its meaning is defined by the customiser.

argc
    The count of bytes passed to a user customised function.

*argx
    A pointer to an array of bytes passed to a user customised function. Its meaning and content is defined by the customiser.

baud
    The speed of serial communication (I2C, SPI, serial link, waves) in bits per second.

bit A value of 0 or 1.

bits
    A value used to select GPIO. If bit n of bits is set then GPIO n is selected.
    A convenient way to set bit n is to or in (1<<n).
    e.g. to select bits 5, 9, 23 you could use (1<<5) | (1<<9) | (1<<23).

bsc_xfer_t
        typedef struct
        {
           uint32_t control;          // Write
           int rxCnt;                 // Read only
           char rxBuf[BSC_FIFO_SIZE]; // Read only
           int txCnt;                 // Write
           char txBuf[BSC_FIFO_SIZE]; // Write
        } bsc_xfer_t;

*bscxfer
    A pointer to a bsc_xfer_t object used to control a BSC transfer.

*buf
    A buffer to hold data being sent or being received.

bufSize
    The size in bytes of a buffer.

bVal: 0-255 (Hex 0x0-0xFF, Octal 0-0377)
    An 8-bit byte value.

callback_id
    A value >=0, as returned by a call to a callback function, one of
    callback
    callback_ex
    event_callback
    event_callback_ex
    The id is passed to callback_cancel or event_callback_cancel to cancel the callback.

CBFunc_t
        typedef void (*CBFunc_t)
           (int pi, unsigned user_gpio, unsigned level, uint32_t tick);

CBFuncEx_t
        typedef void (*CBFuncEx_t)
           (int pi, unsigned user_gpio, unsigned level, uint32_t tick, void * userdata);

char
    A single character, an 8 bit quantity able to store 0-255.

clkfreq: 4689-250M (13184-375M for the BCM2711)
    The hardware clock frequency.

count
    The number of bytes to be transferred in a file, I2C, SPI, or serial command.

CS  The GPIO used for the slave select signal when bit banging SPI.

data_bits: 1-32
    The number of data bits in each character of serial data.
        #define PI_MIN_WAVE_DATABITS 1
        #define PI_MAX_WAVE_DATABITS 32

double
    A floating point number.

dutycycle: 0-range
    A number representing the ratio of on time to off time for PWM.
    The number may vary between 0 and range (default 255) where 0 is off and range is fully on.

edge
    Used to identify a GPIO level transition of interest. A rising edge is a level change from 0 to 1. A falling edge is a level change from 1 to 0.
        RISING_EDGE  0
        FALLING_EDGE 1
        EITHER_EDGE. 2

errnum
    A negative number indicating a function call failed and the nature of the error.

event: 0-31
    An event is a signal used to inform one or more consumers to start an action.

evtCBFunc_t
        typedef void (*evtCBFunc_t)
           (int pi, unsigned event, uint32_t tick);

evtCBFuncEx_t
        typedef void (*evtCBFuncEx_t)
           (int pi, unsigned event, uint32_t tick, void *userdata);

f   A function.

*file
    A full file path. To be accessible the path must match an entry in /opt/pigpio/access.

*fpat
    A file path which may contain wildcards. To be accessible the path must match an entry in /opt/pigpio/access.

frequency: >=0
    The number of times a GPIO is swiched on and off per second. This can be set per GPIO and may be as little as 5Hz or as much as 40KHz. The GPIO will be on for a proportion of the time as defined by its dutycycle.

gpio
    A Broadcom numbered GPIO, in the range 0-53.
    There are 54 General Purpose Input Outputs (GPIO) named GPIO0 through GPIO53.
    They are split into two banks. Bank 1 consists of GPIO0 through GPIO31. Bank 2 consists of GPIO32 through GPIO53.
    All the GPIO which are safe for the user to read and write are in bank 1. Not all GPIO in bank 1 are safe though. Type 1 boards have 17 safe GPIO. Type 2 boards have 21. Type 3 boards have 26.
    See get_hardware_revision.
    The user GPIO are marked with an X in the following table.
                  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
        Type 1    X  X  -  -  X  -  -  X  X  X  X  X  -  -  X  X
        Type 2    -  -  X  X  X  -  -  X  X  X  X  X  -  -  X  X
        Type 3          X  X  X  X  X  X  X  X  X  X  X  X  X  X
                 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
        Type 1    -  X  X  -  -  X  X  X  X  X  -  -  -  -  -  -
        Type 2    -  X  X  -  -  -  X  X  X  X  -  X  X  X  X  X
        Type 3    X  X  X  X  X  X  X  X  X  X  X  X  -  -  -  -

gpioPulse_t
        typedef struct
        {
           uint32_t gpioOn;
           uint32_t gpioOff;
           uint32_t usDelay;
        } gpioPulse_t;

gpioThreadFunc_t
        typedef void *(gpioThreadFunc_t) (void *);

handle: >=0
    A number referencing an object opened by one of
    file_open
    i2c_open
    notify_open
    serial_open
    spi_open

i2c_addr: 0-0x7F
    The address of a device on the I2C bus.

i2c_bus: >=0
    An I2C bus number.

i2c_flags: 0
    Flags which modify an I2C open command. None are currently defined.

i2c_reg: 0-255
    A register of an I2C device.

*inBuf
    A buffer used to pass data to a function.

inLen
    The number of bytes of data in a buffer.

int A whole number, negative or positive.

int32_t
    A 32-bit signed value.

invert
    A flag used to set normal or inverted bit bang serial data level logic.

level
    The level of a GPIO. Low or High.
        PI_OFF 0
        PI_ON 1
        PI_CLEAR 0
        PI_SET 1
        PI_LOW 0
        PI_HIGH 1
    There is one exception. If a watchdog expires on a GPIO the level will be reported as PI_TIMEOUT. See set_watchdog.
        PI_TIMEOUT 2

MISO
    The GPIO used for the MISO signal when bit banging SPI.

mode
    1. The operational mode of a GPIO, normally INPUT or OUTPUT.
        PI_INPUT 0
        PI_OUTPUT 1
        PI_ALT0 4
        PI_ALT1 5
        PI_ALT2 6
        PI_ALT3 7
        PI_ALT4 3
        PI_ALT5 2
    2. The mode of waveform transmission.
        PI_WAVE_MODE_ONE_SHOT      0
        PI_WAVE_MODE_REPEAT        1
        PI_WAVE_MODE_ONE_SHOT_SYNC 2
        PI_WAVE_MODE_REPEAT_SYNC   3
    3. A file open mode.
        PI_FILE_READ  1
        PI_FILE_WRITE 2
        PI_FILE_RW    3
    The following values can be or'd into the mode.
        PI_FILE_APPEND 4
        PI_FILE_CREATE 8
        PI_FILE_TRUNC  16

MOSI
    The GPIO used for the MOSI signal when bit banging SPI.

numBytes
    The number of bytes used to store characters in a string. Depending on the number of bits per character there may be 1, 2, or 4 bytes per character.

numPar: 0-10
    The number of parameters passed to a script.

numPulses
    The number of pulses to be added to a waveform.

offset
    The associated data starts this number of microseconds from the start of the waveform.

*outBuf
    A buffer used to return data from a function.

outLen
    The size in bytes of an output buffer.

pad: 0-2
    A set of GPIO which share common drivers.
    Pad GPIO
    0 0-27
    1 28-45
    2 46-53

padStrength: 1-16
    The mA which may be drawn from each GPIO whilst still guaranteeing the high and low levels.

*param
    An array of script parameters.

pi  An integer defining a connected Pi. The value is returned by pigpio_start upon success.

*portStr
    A string specifying the port address used by the Pi running the pigpio daemon. It may be NULL in which case "8888" is used unless overridden by the PIGPIO_PORT environment variable.

*pth
    A thread identifier, returned by start_thread.

pthread_t
    A thread identifier.

pud: 0-2
    The setting of the pull up/down resistor for a GPIO, which may be off, pull-up, or pull-down.
        PI_PUD_OFF 0
        PI_PUD_DOWN 1
        PI_PUD_UP 2

pulseLen
    1-100, the length of a trigger pulse in microseconds.

*pulses
    An array of pulses to be added to a waveform.

pulsewidth: 0, 500-2500
        PI_SERVO_OFF 0
        PI_MIN_SERVO_PULSEWIDTH 500
        PI_MAX_SERVO_PULSEWIDTH 2500

PWMduty: 0-1000000 (1M)
    The hardware PWM dutycycle.
        #define PI_HW_PWM_RANGE 1000000

PWMfreq: 1-125M (1-187.5M for the BCM2711)
    The hardware PWM frequency.
        #define PI_HW_PWM_MIN_FREQ 1
        #define PI_HW_PWM_MAX_FREQ 125000000
        #define PI_HW_PWM_MAX_FREQ_2711 187500000

range: 25-40000
    The permissible dutycycle values are 0-range.
        PI_MIN_DUTYCYCLE_RANGE 25
        PI_MAX_DUTYCYCLE_RANGE 40000

*retBuf
    A buffer to hold a number of bytes returned to a used customised function,

retMax
    The maximum number of bytes a user customised function should return.

*rxBuf
    A pointer to a buffer to receive data.

SCL The user GPIO to use for the clock when bit banging I2C.

SCLK
    The GPIO used for the SCLK signal when bit banging SPI.

*script
    A pointer to the text of a script.

script_id
    An id of a stored script as returned by store_script.

*scriptName
    The name of a shell_ script to be executed. The script must be present in /opt/pigpio/cgi and must have execute permission.

*scriptString
    The string to be passed to a shell_ script to be executed.

SDA The user GPIO to use for data when bit banging I2C.

seconds
    The number of seconds.

seekFrom
        PI_FROM_START   0
        PI_FROM_CURRENT 1
        PI_FROM_END     2

seekOffset
    The number of bytes to move forward (positive) or backwards (negative) from the seek position (start, current, or end of file).

ser_flags
    Flags which modify a serial open command. None are currently defined.

*ser_tty
    The name of a serial tty device, e.g. /dev/ttyAMA0, /dev/ttyUSB0, /dev/tty1.

size_t
    A standard type used to indicate the size of an object in bytes.

spi_channel
    A SPI channel, 0-2.

spi_flags
    See spi_open and bb_spi_open.

steady: 0-300000
    The number of microseconds level changes must be stable for before reporting the level changed (set_glitch_filter) or triggering the active part of a noise filter (set_noise_filter).

stop_bits: 2-8
    The number of (half) stop bits to be used when adding serial data to a waveform.
        #define PI_MIN_WAVE_HALFSTOPBITS 2
        #define PI_MAX_WAVE_HALFSTOPBITS 8

*str
     An array of characters.

thread_func
    A function of type gpioThreadFunc_t used as the main function of a thread.

timeout
    A GPIO watchdog timeout in milliseconds.
        PI_MIN_WDOG_TIMEOUT 0
        PI_MAX_WDOG_TIMEOUT 60000

*txBuf
    An array of bytes to transmit.

uint32_t: 0-0-4,294,967,295 (Hex 0x0-0xFFFFFFFF)
    A 32-bit unsigned value.

unsigned
    A whole number >= 0.

user_gpio
    0-31, a Broadcom numbered GPIO.
    See gpio.

*userdata
    A pointer to arbitrary user data. This may be used to identify the instance.
    You must ensure that the pointer is in scope at the time it is processed. If it is a pointer to a global this is automatic. Do not pass the address of a local variable. If you want to pass a transient object then use the following technique.
    In the calling function:
        user_type *userdata;
        user_type my_userdata;
        userdata = malloc(sizeof(user_type));
        *userdata = my_userdata;
    In the receiving function:
        user_type my_userdata = *(user_type*)userdata;
        free(userdata);

void
    Denoting no parameter is required

wave_add_*
    One of
    wave_add_new
    wave_add_generic
    wave_add_serial

wave_id
    A number representing a waveform created by wave_create.

wave_send_*
    One of
    wave_send_once
    wave_send_repeat

wVal: 0-65535 (Hex 0x0-0xFFFF, Octal 0-0177777)
    A 16-bit word value.

pigpiod_if2 Error Codes
    typedef enum
    {
       pigif_bad_send           = -2000,
       pigif_bad_recv           = -2001,
       pigif_bad_getaddrinfo    = -2002,
       pigif_bad_connect        = -2003,
       pigif_bad_socket         = -2004,
       pigif_bad_noib           = -2005,
       pigif_duplicate_callback = -2006,
       pigif_bad_malloc         = -2007,
       pigif_bad_callback       = -2008,
       pigif_notify_failed      = -2009,
       pigif_callback_not_found = -2010,
       pigif_unconnected_pi     = -2011,
       pigif_too_many_pis       = -2012,
    } pigifError_t;

SEE ALSO
pigpiod(1), pig2vcd(1), pigs(1), pigpio(3), pigpiod_if(3)

AUTHOR
joan@abyz.me.uk