THIS LIBRARY IS DEPRECATED. NEW CODE SHOULD BE WRITTEN TO USE THE MORE VERSATILE pigpiod_if2 LIBRARY.

pigpiod_if 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_if.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_if -lrt

to run make sure the pigpio daemon is running

sudo pigpiod

 ./prog # sudo is not required to run programs linked to pigpiod_if

For examples see x_pigpiod_if.c within the pigpio archive file.

Notes

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

OVERVIEW


ESSENTIAL

pigpio_start	Connects to the pigpio daemon
pigpio_stop	Disconnects from the pigpio daemon

BEGINNER

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

set_PWM_dutycycle	Start/stop PWM pulses on a GPIO
get_PWM_dutycycle	Get the PWM dutycycle in use on a GPIO

set_servo_pulsewidth	Start/stop servo pulses on a GPIO
get_servo_pulsewidth	Get the servo pulsewidth in use on a GPIO

callback	Create GPIO level change callback
callback_ex	Create GPIO level change callback
callback_cancel	Cancel a callback
wait_for_edge	Wait for GPIO level change

INTERMEDIATE

gpio_trigger	Send a trigger pulse to a GPIO.

set_watchdog	Set a watchdog on a GPIO.

set_PWM_range	Configure PWM range for a GPIO
get_PWM_range	Get configured PWM range for a GPIO

set_PWM_frequency	Configure PWM frequency for a GPIO
get_PWM_frequency	Get configured PWM frequency for 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

start_thread	Start a new thread
stop_thread	Stop a previously started thread

ADVANCED

get_PWM_real_range	Get underlying PWM range for a GPIO

notify_open	Request a notification handle
notify_begin	Start notifications for selected GPIO
notify_pause	Pause notifications
notify_close	Close a notification

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

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

SCRIPTS

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

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_chain	Transmits a chain of waveforms

wave_tx_busy	Checks to see if the waveform has ended
wave_tx_stop	Aborts the current waveform

wave_get_micros	Length in microseconds 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

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

I2C

i2c_open	Opens an I2C device
i2c_close	Closes an I2C device

i2c_write_quick	smbus write quick
i2c_write_byte	smbus write byte
i2c_read_byte	smbus read byte
i2c_write_byte_data	smbus write byte data
i2c_write_word_data	smbus write word data
i2c_read_byte_data	smbus read byte data
i2c_read_word_data	smbus read word data
i2c_process_call	smbus process call
i2c_write_block_data	smbus write block data
i2c_read_block_data	smbus read block data
i2c_block_process_call	smbus block process call

i2c_write_i2c_block_data	smbus write I2C block data
i2c_read_i2c_block_data	smbus read I2C block data

i2c_read_device	Reads the raw I2C device
i2c_write_device	Writes the raw I2C device

i2c_zip	Performs multiple I2C transactions

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

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

SERIAL

serial_open	Opens a serial device
serial_close	Closes a serial device

serial_write_byte	Writes a byte to a serial device
serial_read_byte	Reads a byte from a serial device
serial_write	Writes bytes to a serial device
serial_read	Reads bytes from a serial device

serial_data_available	Returns number of bytes ready to be read

CUSTOM

custom_1	User custom function 1
custom_2	User custom function 2

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_if 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_if 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.

void pigpio_stop(void)

Terminates the connection to the pigpio daemon and releases resources used by the library.

int set_mode(unsigned gpio, unsigned mode)

Set the GPIO mode.

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(unsigned gpio)

Get the GPIO mode.

gpio: 0-53.

Returns the GPIO mode if OK, otherwise PI_BAD_GPIO.

int set_pull_up_down(unsigned gpio, unsigned pud)

Set or clear the GPIO pull-up/down resistor.

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(unsigned gpio)

Read the GPIO level.

gpio:0-53.

Returns the GPIO level if OK, otherwise PI_BAD_GPIO.

int gpio_write(unsigned gpio, unsigned level)

Write the GPIO level.

 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(unsigned user_gpio, unsigned dutycycle)

Start (non-zero dutycycle) or stop (0) PWM pulses on the GPIO.

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(unsigned user_gpio)

Return the PWM dutycycle in use on a GPIO.

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(unsigned user_gpio, unsigned range)

Set the range of PWM values to be used on the GPIO.

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(unsigned user_gpio)

Get the range of PWM values being used on the GPIO.

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(unsigned user_gpio)

Get the real underlying range of PWM values being used on the GPIO.

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(unsigned user_gpio, unsigned frequency)

Set the frequency (in Hz) of the PWM to be used on the GPIO.

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(unsigned user_gpio)

Get the frequency of PWM being used on the GPIO.

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(unsigned user_gpio, unsigned pulsewidth)

Start (500-2500) or stop (0) servo pulses on the GPIO.

 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(unsigned user_gpio)

Return the servo pulsewidth in use on a GPIO.

user_gpio: 0-31.

Returns 0 if OK, otherwise PI_BAD_USER_GPIO or PI_NOT_SERVO_GPIO.

int notify_open(void)

Get a free notification handle.

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(unsigned handle, uint32_t bits)

Start notifications on a previously opened handle.

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: two flags are defined, PI_NTFY_FLAGS_WDOG and PI_NTFY_FLAGS_ALIVE.

PI_NTFY_FLAGS_WDOG, if bit 5 is set then bits 0-4 of the flags indicate a GPIO which has had a watchdog timeout.

PI_NTFY_FLAGS_ALIVE, if bit 6 is set this indicates a keep alive signal on the pipe/socket and is sent once a minute in the absence of other notification activity.

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(unsigned handle)

Pause notifications on a previously opened handle.

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(unsigned handle)

Stop notifications on a previously opened handle and release the handle for reuse.

handle: 0-31 (as returned by notify_open)

Returns 0 if OK, otherwise PI_BAD_HANDLE.

int set_watchdog(unsigned user_gpio, unsigned timeout)

Sets a watchdog for a GPIO.

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(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.

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(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.

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(void)

Read the levels of the bank 1 GPIO (GPIO 0-31).

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(void)

Read the levels of the bank 2 GPIO (GPIO 32-53).

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(uint32_t bits)

Clears GPIO 0-31 if the corresponding bit in bits is set.

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(uint32_t bits)

Clears GPIO 32-53 if the corresponding bit (0-21) in bits is set.

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(uint32_t bits)

Sets GPIO 0-31 if the corresponding bit in bits is set.

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(uint32_t bits)

Sets GPIO 32-53 if the corresponding bit (0-21) in bits is set.

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(unsigned gpio, unsigned clkfreq)

Starts a hardware clock on a GPIO at the specified frequency. Frequencies above 30MHz are unlikely to work.

     gpio: see description
frequency: 0 (off) or 4689-250000000 (250M)

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(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_once, wave_send_repeat, 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).

   gpio: see descripton
PWMfreq: 0 (off) or 1-125000000 (125M)
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

uint32_t get_current_tick(void)

Gets the current system tick.

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(void)

Get the Pi's hardware revision number.

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(void)

Returns the pigpio version.

int wave_clear(void)

This function clears all waveforms and any data added by calls to the wave_add_* functions.

Returns 0 if OK.

int wave_add_new(void)

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.

Returns 0 if OK.

int wave_add_generic(unsigned numPulses, gpioPulse_t *pulses)

This function adds a number of pulses to the current waveform.

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(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.

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(void)

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.

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(unsigned wave_id)

This function deletes the waveform with id wave_id.

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(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.

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(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.

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_chain(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.

    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_if.h>

#define WAVES 5
#define GPIO 4

int main(int argc, char *argv[])
{
   int i, wid[WAVES];

   if (pigpio_start(0, 0)<0) return -1;

   set_mode(GPIO, PI_OUTPUT);

   for (i=0; i<WAVES; i++)
   {
      wave_add_generic(2, (gpioPulse_t[])
         {{1<<GPIO, 0,        20},
          {0, 1<<GPIO, (i+1)*200}});

      wid[i] = wave_create();
   }

   wave_chain((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()) time_sleep(0.1);

   for (i=0; i<WAVES; i++) wave_delete(wid[i]);

   pigpio_stop();
}

int wave_tx_busy(void)

This function checks to see if a waveform is currently being transmitted.

Returns 1 if a waveform is currently being transmitted, otherwise 0.

int wave_tx_stop(void)

This function stops the transmission of the current waveform.

Returns 0 if OK.

This function is intended to stop a waveform started with the repeat mode.

int wave_get_micros(void)

This function returns the length in microseconds of the current waveform.

int wave_get_high_micros(void)

This function returns the length in microseconds of the longest waveform created since the pigpio daemon was started.

int wave_get_max_micros(void)

This function returns the maximum possible size of a waveform in
microseconds.

int wave_get_pulses(void)

This function returns the length in pulses of the current waveform.

int wave_get_high_pulses(void)

This function returns the length in pulses of the longest waveform created since the pigpio daemon was started.

int wave_get_max_pulses(void)

This function returns the maximum possible size of a waveform in pulses.

int wave_get_cbs(void)

This function returns the length in DMA control blocks of the current waveform.

int wave_get_high_cbs(void)

This function returns the length in DMA control blocks of the longest waveform created since the pigpio daemon was started.

int wave_get_max_cbs(void)

This function returns the maximum possible size of a waveform in DMA control blocks.

int gpio_trigger(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.

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(char *script)

This function stores a script for later execution.

See http://abyz.me.uk/rpi/pigpio/pigs.html#Scripts for details.

script: the text of the script.

The function returns a script id if the script is valid, otherwise PI_BAD_SCRIPT.

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

This function runs a stored script.

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(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.

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(unsigned script_id)

This function stops a running script.

script_id: >=0, as returned by store_script.

The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID.

int delete_script(unsigned script_id)

This function deletes a stored script.

script_id: >=0, as returned by store_script.

The function returns 0 if OK, otherwise PI_BAD_SCRIPT_ID.

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

This function opens a GPIO for bit bang reading of serial data.

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(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.

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(unsigned user_gpio)

This function closes a GPIO for bit bang reading of serial data.

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(unsigned user_gpio, unsigned invert)

This function inverts serial logic for big bang serial reads.

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(unsigned i2c_bus, unsigned i2c_addr, unsigned i2c_flags)

This returns a handle for the device at address i2c_addr on bus i2c_bus.

  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.
Comm  (8 bits): Command byte, a data byte which often selects a register.
Data  (8 bits): A data byte.
Count (8 bits): A data byte containing the length of a block operation.

[..]: Data sent by the device.

int i2c_close(unsigned handle)

This closes the I2C device associated with the handle.

handle: >=0, as returned by a call to i2c_open.

Returns 0 if OK, otherwise PI_BAD_HANDLE.

int i2c_write_quick(unsigned handle, unsigned bit)

This sends a single bit (in the Rd/Wr bit) to the device associated with handle.

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 Rd/Wr [A] P

int i2c_write_byte(unsigned handle, unsigned bVal)

This sends a single byte to the device associated with handle.

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] Data [A] P

int i2c_read_byte(unsigned handle)

This reads a single byte from the device associated with handle.

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(unsigned handle, unsigned i2c_reg, unsigned bVal)

This writes a single byte to the specified register of the device associated with handle.

 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] Comm [A] Data [A] P

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

This writes a single 16 bit word to the specified register of the device associated with handle.

 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] Comm [A] DataLow [A] DataHigh [A] P

int i2c_read_byte_data(unsigned handle, unsigned i2c_reg)

This reads a single byte from the specified register of the device associated with handle.

 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] Comm [A] S Addr Rd [A] [Data] NA P

int i2c_read_word_data(unsigned handle, unsigned i2c_reg)

This reads a single 16 bit word from the specified register of the device associated with handle.

 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] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P

int i2c_process_call(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.

 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] Comm [A] DataLow [A] DataHigh [A]
   S Addr Rd [A] [DataLow] A [DataHigh] NA P

int i2c_write_block_data(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.

 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] Comm [A] Count [A] Data [A] Data [A] ... [A] Data [A] P

int i2c_read_block_data(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.

 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] Comm [A]
   S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P

int i2c_block_process_call(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.

 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] Comm [A] Count [A] Data [A] ...
   S Addr Rd [A] [Count] A [Data] ... A P

int i2c_read_i2c_block_data(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.

 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] Comm [A]
   S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P

int i2c_write_i2c_block_data(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.

 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] Comm [A] Data [A] Data [A] ... [A] Data [A] P

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

This reads count bytes from the raw device into buf.

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.

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

This writes count bytes from buf to the raw device.

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.

int i2c_zip(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.

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(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

 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(unsigned SDA)

This function stops bit banging I2C on a pair of GPIO previously opened with bb_i2c_open.

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(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.

   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 spi_open(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

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 word.
For bits 9-16 there will be two bytes per word.
For bits 17-32 there will be four bytes per word.

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(unsigned handle)

This functions closes the SPI device identified by the handle.

handle: >=0, as returned by a call to spi_open.

Returns 0 if OK, otherwise PI_BAD_HANDLE.

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

This function reads count bytes of data from the SPI device associated with the handle.

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(unsigned handle, char *buf, unsigned count)

This function writes count bytes of data from buf to the SPI device associated with the handle.

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(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.

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(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.

  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(unsigned handle)

This function closes the serial device associated with handle.

handle: >=0, as returned by a call to serial_open.

Returns 0 if OK, otherwise PI_BAD_HANDLE.

int serial_write_byte(unsigned handle, unsigned bVal)

This function writes bVal to the serial port associated with handle.

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(unsigned handle)

This function reads a byte from the serial port associated with handle.

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(unsigned handle, char *buf, unsigned count)

This function writes count bytes from buf to the the serial port associated with handle.

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(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.

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(unsigned handle)

Returns the number of bytes available to be read from the device associated with handle.

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(unsigned arg1, unsigned arg2, char *argx, unsigned argc)

This function is available for user customisation.

It returns a single integer value.

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(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.

  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 callback(unsigned user_gpio, unsigned edge, CBFunc_t f)

This function initialises a new callback.

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(unsigned user_gpio, unsigned edge, CBFuncEx_t f, void *userdata)

This function initialises a new callback.

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 user, 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(unsigned user_gpio, unsigned edge, double timeout)

This function waits for edge on the GPIO for up to timeout seconds.

user_gpio: 0-31.
     edge: RISING_EDGE, FALLING_EDGE, or EITHER_EDGE.
  timeout: >=0.

The function returns 1 if the edge occurred, otherwise 0.

The function returns when the edge occurs or after the timeout.

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).

*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 >=0, as returned by a call to callback or callback_ex. This is passed to callback_cancel to cancel the callback.

CBFunc_t

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

CBFuncEx_t

typedef void (*CBFuncEx_t)
   (unsigned user_gpio, unsigned level, uint32_t tick, void * user);

char

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

clkfreq: 4689-250000000 (250M)

The hardware clock frequency.

count

The number of bytes to be transferred in an I2C, SPI, or Serial command.

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.

f

A function.

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 i2c_open, notify_open, serial_open, and 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.

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

mode: 0-7

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

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.

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: 1-125000000 (125M)

The hardware PWM frequency.

#define PI_HW_PWM_MIN_FREQ 1
#define PI_HW_PWM_MAX_FREQ 125000000

range: 25-40000

The permissible dutycycle values are 0-range.

PI_MIN_DUTYCYCLE_RANGE 25
PI_MAX_DUTYCYCLE_RANGE 40000

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

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.

wVal: 0-65535 (Hex 0x0-0xFFFF, Octal 0-0177777)

A 16-bit word value.

pigpiod_if 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,
} pigifError_t;

Features

GPIO

Notes

Usage

Notes

OVERVIEW

FUNCTIONS

double time_time(void)

void time_sleep(double seconds)

char *pigpio_error(int errnum)

unsigned pigpiod_if_version(void)

pthread_t *start_thread(gpioThreadFunc_t thread_func, void *userdata)

void stop_thread(pthread_t *pth)

int pigpio_start(char *addrStr, char *portStr)

void pigpio_stop(void)

int set_mode(unsigned gpio, unsigned mode)

int get_mode(unsigned gpio)

int set_pull_up_down(unsigned gpio, unsigned pud)

int gpio_read(unsigned gpio)

int gpio_write(unsigned gpio, unsigned level)

int set_PWM_dutycycle(unsigned user_gpio, unsigned dutycycle)

int get_PWM_dutycycle(unsigned user_gpio)

int set_PWM_range(unsigned user_gpio, unsigned range)

int get_PWM_range(unsigned user_gpio)

int get_PWM_real_range(unsigned user_gpio)

int set_PWM_frequency(unsigned user_gpio, unsigned frequency)

int get_PWM_frequency(unsigned user_gpio)

int set_servo_pulsewidth(unsigned user_gpio, unsigned pulsewidth)

int get_servo_pulsewidth(unsigned user_gpio)

int notify_open(void)

int notify_begin(unsigned handle, uint32_t bits)

int notify_pause(unsigned handle)

int notify_close(unsigned handle)

int set_watchdog(unsigned user_gpio, unsigned timeout)

int set_glitch_filter(unsigned user_gpio, unsigned steady)

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

uint32_t read_bank_1(void)

uint32_t read_bank_2(void)

int clear_bank_1(uint32_t bits)

int clear_bank_2(uint32_t bits)

int set_bank_1(uint32_t bits)

int set_bank_2(uint32_t bits)

int hardware_clock(unsigned gpio, unsigned clkfreq)

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

uint32_t get_current_tick(void)

uint32_t get_hardware_revision(void)

uint32_t get_pigpio_version(void)

int wave_clear(void)

int wave_add_new(void)

int wave_add_generic(unsigned numPulses, gpioPulse_t *pulses)

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

int wave_create(void)

int wave_delete(unsigned wave_id)

int wave_send_once(unsigned wave_id)

int wave_send_repeat(unsigned wave_id)

int wave_chain(char *buf, unsigned bufSize)

int wave_tx_busy(void)

int wave_tx_stop(void)

int wave_get_micros(void)

int wave_get_high_micros(void)

int wave_get_max_micros(void)

int wave_get_pulses(void)

int wave_get_high_pulses(void)

int wave_get_max_pulses(void)

int wave_get_cbs(void)

int wave_get_high_cbs(void)

int wave_get_max_cbs(void)

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

int store_script(char *script)

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

int script_status(unsigned script_id, uint32_t *param)

int stop_script(unsigned script_id)

int delete_script(unsigned script_id)

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

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

int bb_serial_read_close(unsigned user_gpio)

int bb_serial_invert(unsigned user_gpio, unsigned invert)

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

int i2c_close(unsigned handle)

int i2c_write_quick(unsigned handle, unsigned bit)

pthread_t start_thread(gpioThreadFunc_t thread_func, void userdata)

int pigpio_start(char addrStr, char portStr)

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

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

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

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