Ubuntu Manpages

lgpio

A C library to manipulate a local SBC's GPIO.

#include <lgpio.h>

gcc -Wall -o prog prog.c -llgpio

./prog

lgpio is a C library for Linux Single Board Computers which allows control of the General Purpose Input Output pins.

o reading and writing GPIO singly and in groups

o software timed PWM and waves

o GPIO callbacks

o pipe notification of GPIO alerts

o I2C wrapper

o SPI wrapper

o serial link wrapper

o a simple interface to start and stop new threads

Include <lgpio.h> in your source files.

Assuming your source is in a single file called prog.c use the following command to build and run the executable.

gcc -Wall -o prog prog.c -llgpio

For examples of usage see the C programs within the lg archive file.

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

lgGpiochipOpen Opens a gpiochip device
lgGpiochipClose Closes a gpiochip device

lgGpioGetChipInfo Gets gpiochip information
lgGpioGetLineInfo Gets gpiochip line information
lgGpioGetMode Gets the mode of a GPIO

lgGpioSetUser Notifies Linux of the GPIO user

lgGpioClaimInput Claims a GPIO for input
lgGpioClaimOutput Claims a GPIO for output
lgGpioClaimAlert Claims a GPIO for alerts
lgGpioFree Frees a GPIO

lgGroupClaimInput Claims a group of GPIO for inputs
lgGroupClaimOutput Claims a group of GPIO for outputs
lgGroupFree Frees a group of GPIO

lgGpioRead Reads a GPIO
lgGpioWrite Writes a GPIO

lgGroupRead Reads a group of GPIO
lgGroupWrite Writes a group of GPIO

lgTxPulse Starts pulses on a GPIO
lgTxPwm Starts PWM pulses on a GPIO
lgTxServo Starts Servo pulses on a GPIO
lgTxWave Starts a wave on a group of GPIO
lgTxBusy See if tx is active on a GPIO or group
lgTxRoom See if more room for tx on a GPIO or group

lgGpioSetDebounce Sets the debounce time for a GPIO
lgGpioSetWatchdog Sets the watchdog time for a GPIO

lgGpioSetAlertsFunc Starts a GPIO callback
lgGpioSetSamplesFunc Starts a GPIO callback for all GPIO

lgI2cOpen Opens an I2C device
lgI2cClose Closes an I2C device

lgI2cWriteQuick SMBus write quick

lgI2cReadByte SMBus read byte
lgI2cWriteByte SMBus write byte

lgI2cReadByteData SMBus read byte data
lgI2cWriteByteData SMBus write byte data

lgI2cReadWordData SMBus read word data
lgI2cWriteWordData SMBus write word data

lgI2cReadBlockData SMBus read block data
lgI2cWriteBlockData SMBus write block data

lgI2cReadI2CBlockData SMBus read I2C block data
lgI2cWriteI2CBlockData SMBus write I2C block data

lgI2cReadDevice Reads the raw I2C device
lgI2cWriteDevice Writes the raw I2C device

lgI2cProcessCall SMBus process call
lgI2cBlockProcessCall SMBus block process call

lgI2cSegments Performs multiple I2C transactions
lgI2cZip Performs multiple I2C transactions

lgNotifyOpen Request a notification
lgNotifyClose Close a notification
lgNotifyPause Pause notifications
lgNotifyResume Start notifications

lgSerialOpen Opens a serial device
lgSerialClose Closes a serial device

lgSerialReadByte Reads a byte from a serial device
lgSerialWriteByte Writes a byte to a serial device

lgSerialRead Reads bytes from a serial device
lgSerialWrite Writes bytes to a serial device

lgSerialDataAvailable Returns number of bytes ready to be read

lgSpiOpen Opens a SPI device
lgSpiClose Closes a SPI device

lgSpiRead Reads bytes from a SPI device
lgSpiWrite Writes bytes to a SPI device

lgSpiXfer Transfers bytes with a SPI device

lgThreadStart Start a new thread
lgThreadStop Stop a previously started thread

lguVersion Gets the library version
lguSbcName Gets the host name of the SBC

lguGetInternal Get an internal configuration value
lguSetInternal Set an internal configuration value

lguSleep Sleeps for a given time

lguTimestamp Gets the current timestamp
lguTime Gets the current time

lguErrorText Gets a text description of an error code

lguSetWorkDir Set the working directory
lguGetWorkDir Get the working directory

This returns a handle to a gpiochip device. 

gpioDev: >= 0

If OK returns a handle (>= 0).

On failure returns a negative error code.

Example

h = lgGpiochipOpen(0); // open /dev/gpiochip0


if (h >= 0)
{
   // open ok
}
else
{
   // open error
}

This closes an opened gpiochip device. 

handle: >= 0 (as returned by lgGpiochipOpen)

If OK returns 0.

On failure returns a negative error code.

Example

status = lgGpiochipClose(h); // close gpiochip


if (status < 0)
{
   // close failed
}

This returns information about a gpiochip. 

  handle: >= 0 (as returned by lgGpiochipOpen)
chipInfo: A pointer to space for a lgChipInfo_t object

If OK returns 0 and updates chipInfo.

On failure returns a negative error code.

This command gets the number of GPIO on the gpiochip, its name, and its usage.

Example

lgChipInfo_t cInfo;


status = lgGpioGetChipInfo(h, &cInfo);


if (status == LG_OKAY)
{
   printf("lines=%d name=%s label=%s0,
      cInfo.lines, cInfo.name, cInfo.label))
}

Returns information about a GPIO. 

  handle: >= 0 (as returned by lgGpiochipOpen)
    gpio: >= 0, as legal for the gpiochip
lineInfo: A pointer to space for a lgLineInfo_t object

If OK returns 0 and updates lineInfo.

On failure returns a negative error code.

This command gets information for a GPIO of a gpiochip. In particular it gets the GPIO number, flags, its user, and its purpose.

The meaning of the flags bits are as given for the mode by lgGpioGetMode.

The user and purpose fields are filled in by the software which has claimed the GPIO and may be blank.

Example

lgLineInfo_t lInfo;


status = lgGpioGetLineInfo(h, gpio, &lInfo);


if (status == LG_OKAY)
{
   printf("lFlags=%d name=%s user=%s0,
      lInfo.lFlags, lInfo.name, lInfo.user))
}

Returns the GPIO mode. 

  handle: >= 0 (as returned by lgGpiochipOpen)
    gpio: >= 0, as legal for the gpiochip

If OK returns the GPIO mode.

On failure returns a negative error code.

Bit Value Meaning
0 1 Kernel: In use by the kernel
1 2 Kernel: Output
2 4 Kernel: Active low
3 8 Kernel: Open drain
4 16 Kernel: Open source
5 32 Kernel: Pull up set
6 64 Kernel: Pull down set
7 128 Kernel: Pulls off set
8 256 LG: Input
9 512 LG: Output
10 1024 LG: Alert
11 2048 LG: Group
12 4096 LG: ---
13 8192 LG: ---
14 16384 LG: ---
15 32768 LG: ---
16 65536 Kernel: Input
17 1<<17 Kernel: Rising edge alert
18 1<<18 Kernel: Falling edge alert
19 1<<19 Kernel: Realtime clock alert

The LG bits are only set if the query was made by the process that owns the GPIO.

This sets the user string to be associated with each claimed GPIO. 

  handle: >= 0 (as returned by lgGpiochipOpen)
gpiouser: a string up to 32 characters long

If OK returns 0.

On failure returns a negative error code.

Example

status = lgGpioSetUser(h, "my_title");

This claims a GPIO for input. 

handle: >= 0 (as returned by lgGpiochipOpen)
lFlags: line flags for the GPIO
  gpio: the GPIO to be claimed

If OK returns 0.

On failure returns a negative error code.

The line flags may be used to set the GPIO as active low, open drain, or open source.

Example

// open GPIO 23 for input
status = lgGpioClaimInput(h, 0, 23);

This claims a GPIO for output. 

handle: >= 0 (as returned by lgGpiochipOpen)
lFlags: line flags for the GPIO
  gpio: the GPIO to be claimed
 level: the initial level to set for the GPIO

If OK returns 0.

On failure returns a negative error code.

The line flags may be used to set the GPIO as active low, open drain, or open source.

If level is zero the GPIO will be initialised low. If any other value is used the GPIO will be initialised high.

Example

// open GPIO 31 for high output
status = lgGpioClaimOutput(h, 0, 31, 1);

This claims a GPIO for alerts on level changes. 

   handle: >= 0 (as returned by lgGpiochipOpen)
   lFlags: line flags for the GPIO
   eFlags: event flags for the GPIO
     gpio: >= 0, as legal for the gpiochip
nfyHandle: >= 0 (as returned by lgNotifyOpen)

If OK returns 0.

On failure returns a negative error code.

The line flags may be used to set the GPIO as active low, open drain, or open source.

The event flags are used to specify alerts for a rising edge, falling edge, or both edges.

The alerts will be sent to a previously opened notification. If you don't want them sent to a notification set nfyHandle to -1.

The alerts will also be sent to any callback registered for the GPIO by lgGpioSetAlertsFunc.

All GPIO alerts are also sent to a callback registered by lgGpioSetSamplesFunc.

Example

status = lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, 16, -1);

This frees a GPIO. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the GPIO to be freed

If OK returns 0.

On failure returns a negative error code.

The GPIO may now be claimed by another user or for a different purpose.

Example

status = lgGpioFree(h, 16);

This claims a group of GPIO for inputs. 

handle: >= 0 (as returned by lgGpiochipOpen)
lFlags: line flags for the GPIO group
 count: the number of GPIO to claim
 gpios: the group GPIO

If OK returns 0.

On failure returns a negative error code.

The line flags may be used to set the group as active low, open drain, or open source.

gpios is an array of one or more GPIO. The first GPIO is called the group leader and is used to reference the group as a whole.

Example

int buttons[4] = {9, 7, 2, 6};


status = lgGroupClaimInput(h, 0, 4, buttons);


if (status == LG_OKAY)
{
   // OK
}
else
{
   // Error
}

This claims a group of GPIO for outputs. 

handle: >= 0 (as returned by lgGpiochipOpen)
lFlags: line flags for the GPIO group
 count: the number of GPIO to claim
 gpios: the group GPIO
levels: the initial level for each GPIO

If OK returns 0.

On failure returns a negative error code.

The line flags may be used to set the group as active low, open drain, or open source.

gpios is an array of one or more GPIO. The first GPIO is called the group leader and is used to reference the group as a whole.

levels is an array of initialisation values for the GPIO. If a value is zero the corresponding GPIO will be initialised low. If any other value is used the corresponding GPIO will be initialised high.

Example

int leds[7] =   {15, 16, 17, 8, 12, 13, 14};
int levels[7] = { 1,  0,  1, 1,  1,  0,  0};


status = lgGroupClaimInput(h, 0, 7, leds, levels);


if (status == LG_OKAY)
{
   // OK
}
else
{
   // Error
}

This frees all the GPIO associated with a group. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the group to be freed

If OK returns 0.

On failure returns a negative error code.

The GPIO may now be claimed by another user or for a different purpose.

Example

status = lgGroupFree(9); // free buttons

This returns the level of a GPIO. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the GPIO to be read

If OK returns 0 (low) or 1 (high).

On failure returns a negative error code.

This command will work for any claimed GPIO (even if a member of a group). For an output GPIO the value returned will be that last written to the GPIO.

Example

level = lgGpioRead(h, 15); // get level of GPIO 15

This sets the level of an output GPIO. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the GPIO to be written
 level: the level to set

If OK returns 0.

On failure returns a negative error code.

This command will work for any GPIO claimed as an output (even if a member of a group).

If level is zero the GPIO will be set low (0). If any other value is used the GPIO will be set high (1).

Example

status = lgGpioWrite(h, 23, 1); // set GPIO 23 high

This returns the levels read from a group. 

   handle: >= 0 (as returned by lgGpiochipOpen)
     gpio: the group to be read
groupBits: a pointer to a 64-bit memory area for the returned levels

If OK returns the group size and updates groupBits.

On failure returns a negative error code.

This command will work for an output group as well as an input group. For an output group the value returned will be that last written to the group GPIO.

Note that this command will also work on an individual GPIO claimed as an input or output as that is treated as a group with one member.

After a successful read groupBits is set as follows.

Bit 0 is the level of the group leader.
Bit 1 is the level of the second GPIO in the group.
Bit x is the level of GPIO x+1 of the group.

Example

// assuming a read group of 4 buttons: 9, 7, 2, 6.
uint64_t bits;


size = lgGroupRead(h, 9, &bits); // 9 is buttons group leader


if (size >= 0) // size of group is returned so size will be 4
{
   level_9 = (bits >> 0) & 1;
   level_7 = (bits >> 1) & 1;
   level_2 = (bits >> 2) & 1;
   level_6 = (bits >> 3) & 1;
}
else
{
   // error
}

This sets the levels of an output group. 

   handle: >= 0 (as returned by lgGpiochipOpen)
     gpio: the group to be written
groupBits: the level to set if the corresponding bit in groupMask is set
groupMask: a mask indicating the group GPIO to be updated

If OK returns 0.

On failure returns a negative error code.

The values of each GPIO of the group are set according to the bits
of groupBits.

Bit 0 sets the level of the group leader.
Bit 1 sets the level of the second GPIO in the group.
Bit x sets the level of GPIO x+1 in the group.

However this may be modified by the groupMask. A GPIO is only updated if the corresponding bit in the mask is 1.

Example

// assuming an output group of 7 LEDs: 15, 16, 17, 8, 12, 13, 14.


// switch on all LEDs
status = lgGroupWrite(h, 15, 0x7f, 0x7f);


// switch off all LEDs
status = lgGroupWrite(h, 15, 0x00, 0x7f);


// switch on first 4 LEDs, leave others unaltered
status = lgGroupWrite(h, 15, 0x0f, 0x0f);


// switch on LED attached to GPIO 13, leave others unaltered
status = lgGroupWrite(h, 15, 32, 32);

This starts software timed pulses on an output GPIO. 

     handle: >= 0 (as returned by lgGpiochipOpen)
       gpio: the GPIO to be written
    pulseOn: pulse high time in microseconds
   pulseOff: pulse low time in microseconds
pulseOffset: offset from nominal pulse start position
pulseCycles: the number of pulses to be sent, 0 for infinite

If OK returns the number of entries left in the PWM queue for the GPIO.

On failure returns a negative error code.

If both pulseOn and pulseOff are zero pulses will be switched off for that GPIO. The active pulse, if any, will be stopped and any queued pulses will be deleted.

Each successful call to this function consumes one PWM queue entry.

pulseCycles cycles are transmitted (0 means infinite). Each cycle consists of pulseOn microseconds of GPIO high followed by pulseOff microseconds of GPIO low.

PWM is characterised by two values, its frequency (number of cycles per second) and its duty cycle (percentage of high time per cycle).

The set frequency will be 1000000 / (pulseOn + pulseOff) Hz.

The set duty cycle will be pulseOn / (pulseOn + pulseOff) * 100 %.

E.g. if pulseOn is 50 and pulseOff is 100 the frequency will be 6666.67 Hz and the duty cycle will be 33.33 %.

pulseOffset is a microsecond offset from the natural start of the PWM cycle.

For instance if the PWM frequency is 10 Hz the natural start of each cycle is at seconds 0, then 0.1, 0.2, 0.3 etc. In this case if the offset is 20000 microseconds the cycle will start at seconds 0.02, 0.12, 0.22, 0.32 etc.

Another pulse command may be issued to the GPIO before the last has finished.

If the last pulse had infinite cycles then it will be replaced by the new settings at the end of the current cycle. Otherwise it will be replaced by the new settings when all its cycles are compete.

Multiple pulse settings may be queued in this way.

Example

slots_left = lgTxPulse(h,  8, 100000, 100000, 0, 0); // flash LED at 5 Hz


slots_left = lgTxPulse(h, 30, 1500, 18500, 0, 0); // move servo to centre


slots_left = lgTxPulse(h, 30, 2000, 18000, 0, 0); // move servo clockwise

This starts software timed PWM on an output GPIO. 

      handle: >= 0 (as returned by lgGpiochipOpen)
        gpio: the GPIO to be pulsed
pwmFrequency: PWM frequency in Hz (0=off, 0.1-10000)
pwmDutyCycle: PWM duty cycle in % (0-100)
   pwmOffset: offset from nominal pulse start position
   pwmCycles: the number of pulses to be sent, 0 for infinite

If OK returns the number of entries left in the PWM queue for the GPIO.

On failure returns a negative error code.

Each successful call to this function consumes one PWM queue entry.

PWM is characterised by two values, its frequency (number of cycles per second) and its duty cycle (percentage of high time per cycle).

Another PWM command may be issued to the GPIO before the last has finished.

If the last pulse had infinite cycles then it will be replaced by the new settings at the end of the current cycle. Otherwise it will be replaced by the new settings when all its cycles are complete.

Multiple PWM settings may be queued in this way.

This starts software timed servo pulses on an output GPIO.

I would only use software timed servo pulses for testing purposes. The timing jitter will cause the servo to fidget. This may cause it to overheat and wear out prematurely.

        handle: >= 0 (as returned by lgGpiochipOpen)
          gpio: the GPIO to be pulsed
    pulseWidth: pulse high time in microseconds (0=off, 500-2500)
servoFrequency: the number of pulses per second (40-500).
   servoOffset: offset from nominal pulse start position
   servoCycles: the number of pulses to be sent, 0 for infinite

If OK returns the number of entries left in the PWM queue for the GPIO.

On failure returns a negative error code.

Each successful call to this function consumes one PWM queue entry.

Another servo command may be issued to the GPIO before the last has finished.

If the last pulse had infinite cycles then it will be replaced by the new settings at the end of the current cycle. Otherwise it will be replaced by the new settings when all its cycles are compete.

Multiple servo settings may be queued in this way.

This starts a wave on an output group of GPIO. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the group leader
 count: the number of pulses in the wave
pulses: the pulses

If OK returns the number of entries left in the wave queue for the group.

On failure returns a negative error code.

Each successful call to this function consumes one queue entry.

This command starts a wave of pulses.

pulses is an array of pulses to be transmitted on the group.

Each pulse is defined by the following triplet:

bits: the levels to set for the selected GPIO
mask: the GPIO to select
delay: the delay in microseconds before the next pulse

Another wave command may be issued to the group before the last has finished transmission. The new wave will start when the previous wave has competed.

Multiple waves may be queued in this way.

Example

#include <stdio.h>


#include <lgpio.h>


#define PULSES 2000


int main(int argc, char *argv[])
{
   int GPIO[] =   {16, 17, 18, 19, 20, 21};
   int levels[] = { 1,  1,  1,  1,  1,  1};
   int h;
   int e;
   int mask;
   int delay;
   int p;
   lgPulse_t pulses[PULSES];


   h = lgGpiochipOpen(0); // open /dev/gpiochip0


   if (h < 0) { printf("ERROR: %s (%d)0, lguErrorText(h), h); return 1; }


   e =  lgGroupClaimOutput(h, 0, 6, GPIO, levels);


   if (e < 0) { printf("ERROR: %s (%d)0, lguErrorText(e), e); return 1; }


   mask = 0;
   p = 0;


   for (p=0; p<PULSES; p++)
   {
      pulses[p].bits = (p+1)>>2;  // see what sort of pattern we get
      pulses[p].mask = mask;      // with bits and mask changing
      pulses[p].delay = (PULSES + 500) - p;


      if (++mask > 0x3f) mask = 0;
   }


   lgTxWave(h, GPIO[0], p, pulses);


   while (lgTxBusy(h, GPIO[0], LG_TX_WAVE)) lguSleep(0.1);


   lgGpiochipClose(h);
}

This returns true if transmissions of the specified kind are active on the GPIO or group. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the gpio or group to be checked
  kind: LG_TX_PWM or LG_TX_WAVE

If OK returns 1 for busy and 0 for not busy.

On failure returns a negative error code.

Example

while (lgTxBusy(h, 15, LG_TX_PWM)) // wait for PWM to finish on GPIO 15
   lguSleep(0.1);

This returns the number of entries available for queueing transmissions of the specified kind on the GPIO or group. 

handle: >= 0 (as returned by lgGpiochipOpen)
  gpio: the gpio or group to be checked
  kind: LG_TX_PWM or LG_TX_WAVE

If OK returns the number of free entries (0 if none).

On failure returns a negative error code.

Example

while (lgTxRoom(h, 17, LG_TX_WAVE) > 0))
{
   // queue another wave
}

This sets the debounce time for a GPIO. 

     handle: >= 0 (as returned by lgGpiochipOpen)
       gpio: the GPIO to be configured
debounce_us: the debounce time in microseconds

If OK returns 0.

On failure returns a negative error code.

This only affects alerts.

An alert will only be issued if the edge has been stable for at least debounce microseconds.

Generally this is used to debounce mechanical switches (e.g. contact bounce).

Suppose that a square wave at 5 Hz is being generated on a GPIO. Each edge will last 100000 microseconds. If a debounce time of 100001 is set no alerts will be generated, If a debounce time of 99999 is set 10 alerts will be generated per second.

Note that level changes will be timestamped debounce microseconds after the actual level change.

Example

lgSetDebounceTime(h, 16, 1000); // set a millisecond of debounce

This sets the watchdog time for a GPIO. 

     handle: >= 0 (as returned by lgGpiochipOpen)
       gpio: the GPIO to be configured
watchdog_us: the watchdog time in microseconds

If OK returns 0.

On failure returns a negative error code.

This only affects alerts.

A watchdog alert will be sent if no edge alert has been issued for that GPIO in the previous watchdog microseconds.

Note that only one watchdog alert will be sent per stream of edge alerts. The watchdog is reset by the sending of a new edge alert.

The level is set to LG_TIMEOUT (2) for a watchdog alert.

Example

lgSetWatchdogTime(h, 17, 200000); // alert if nothing for 0.2 seconds

This sets up a callback to be called when an alert GPIO changes state. 

  handle: >= 0 (as returned by lgGpiochipOpen)
    gpio: the GPIO to be monitored
     cbf: the callback function
userdata: a pointer to arbitrary user data

If OK returns 0.

On failure returns a negative error code.

Example

#include <stdio.h>
#include <inttypes.h>


#include <lgpio.h>


void afunc(int e, lgGpioAlert_p evt, void *data)
{
   int i;
   int userdata = *(int*)data;


   for (i=0; i<e; i++)
   {
      printf("u=%d t=%"PRIu64" c=%d g=%d l=%d f=%d (%d of %d)0,
         userdata, evt[i].report.timestamp, evt[i].report.chip,
         evt[i].report.gpio, evt[i].report.level,
         evt[i].report.flags, i+1, e);
   }
}


int main(int argc, char *argv[])
{
   int h;
   int e;
   static int userdata=123;


   h = lgGpiochipOpen(0);


   if (h < 0) { printf("ERROR: %s (%d)0, lguErrorText(h), h); return 1; }


   lgGpioSetAlertsFunc(h, GPIO, afunc, &userdata);


   e = lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, 23, -1);


   if (e < 0) { printf("ERROR: %s (%d)0, lguErrorText(e), e); return 1; }


   lguSleep(10);


   lgGpiochipClose(h);
}

Assuming square wave at 800 Hz is being received at GPIO 23.

u=123 ts=1602089980691229623 c=0 g=23 l=1 f=0 (1 of 1)
u=123 ts=1602089980691854934 c=0 g=23 l=0 f=0 (1 of 1)
u=123 ts=1602089980692479308 c=0 g=23 l=1 f=0 (1 of 1)
u=123 ts=1602089980693114566 c=0 g=23 l=0 f=0 (1 of 1)
u=123 ts=1602089980693728784 c=0 g=23 l=1 f=0 (1 of 1)
u=123 ts=1602089980694354355 c=0 g=23 l=0 f=0 (1 of 1)
u=123 ts=1602089980694978468 c=0 g=23 l=1 f=0 (1 of 1)

This sets up a callback to be called when any alert GPIO changes state. 

     cbf: the callback function
userdata: a pointer to arbitrary user data

If OK returns 0.

On failure returns a negative error code.

Note that no handle or gpio is specified. The callback function will receive alerts for all gpiochips and gpio.

Example

#include <stdio.h>
#include <inttypes.h>


#include <lgpio.h>


void afunc(int e, lgGpioAlert_p evt, void *data)
{
   int i;
   int userdata = *(int*)data;


   for (i=0; i<e; i++)
   {
      printf("u=%d t=%"PRIu64" c=%d g=%d l=%d f=%d (%d of %d)0,
         userdata, evt[i].report.timestamp, evt[i].report.chip,
         evt[i].report.gpio, evt[i].report.level,
         evt[i].report.flags, i+1, e);
   }
}


int main(int argc, char *argv[])
{
   int h;
   static int userdata=456;


   h = lgGpiochipOpen(0);


   if (h < 0) { printf("ERROR: %s (%d)0, lguErrorText(h), h); return 1; }


   lgGpioSetSamplesFunc(afunc, &userdata);


   lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, 23, -1);
   lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, 24, -1);
   lgGpioClaimAlert(h, 0, LG_BOTH_EDGES, 25, -1);


   lguSleep(10);


   lgGpiochipClose(h);
}

Assuming square wave at 800 Hz is being received at GPIO 23, 24, 25.

u=456 ts=1602090898869011679 c=0 g=24 l=1 f=0 (1 of 3)
u=456 ts=1602090898869016627 c=0 g=25 l=1 f=0 (2 of 3)
u=456 ts=1602090898869627667 c=0 g=23 l=0 f=0 (3 of 3)
u=456 ts=1602090898869636522 c=0 g=24 l=0 f=0 (1 of 3)
u=456 ts=1602090898869641157 c=0 g=25 l=0 f=0 (2 of 3)
u=456 ts=1602090898870252614 c=0 g=23 l=1 f=0 (3 of 3)
u=456 ts=1602090898870261155 c=0 g=24 l=1 f=0 (1 of 3)
u=456 ts=1602090898870266208 c=0 g=25 l=1 f=0 (2 of 3)
u=456 ts=1602090898870879800 c=0 g=23 l=0 f=0 (3 of 3)
u=456 ts=1602090898870890477 c=0 g=24 l=0 f=0 (1 of 3)
u=456 ts=1602090898870895529 c=0 g=25 l=0 f=0 (2 of 3)
u=456 ts=1602090898871503652 c=0 g=23 l=1 f=0 (3 of 3)

This function requests a free notification.

If OK returns a handle (>= 0).

On failure returns a negative error code.

A notification is a method for being notified of GPIO state changes via a pipe or socket.

The notification pipes are created in the library working directory (see lguGetWorkDir).

Pipe notifications for handle x will be available at the pipe named .lgd-nfy* (where * is the handle number). E.g. if the function returns 15 then the notifications must be read from .lgd-nfy15.

Socket notifications are returned to the socket which requested the handle.

Example

h = lgNotifyOpen();


if (h >= 0)
{
   sprintf(str, ".lgd-nfy%d", h);


   fd = open(str, O_RDONLY);


   if (fd >= 0)
   {
      // Okay.
   }
   else
   {
      // Error.
   }
}
else
{
   // Error.
}

This function restarts notifications on a paused notification. 

handle: >= 0 (as returned by lgNotifyOpen)

If OK returns 0.

On failure returns a negative error code.

The notification gets state changes for each associated GPIO.

Each notification occupies 16 bytes in the fifo and has the following structure.

typedef struct
{
   uint64_t timestamp; // alert time in nanoseconds
   uint8_t chip;       // gpiochip device number
   uint8_t gpio;       // offset into gpio device
   uint8_t level;      // 0=low, 1=high, 2=timeout
   uint8_t flags;      // none currently defined
} lgGpioReport_t;

timestamp: the number of nanoseconds since the epoch (start of 1970) level: indicates the level of the GPIO
flags: no flags are currently defined

For future proofing it is probably best to ignore any notification with non-zero flags.

Example

// Start notifications for associated GPIO.
lgNotifyResume(h);

This function pauses notifications. 

handle: >= 0 (as returned by lgNotifyOpen)

If OK returns 0.

On failure returns a negative error code.

Notifications are suspended until lgNotifyResume is called.

Example

lgNotifyPause(h);

This function stops notifications and frees the handle for reuse. 

handle: >= 0 (as returned by lgNotifyOpen)

If OK returns 0.

On failure returns a negative error code.

Example

lgNotifyClose(h);

This returns a handle for the device at the address on the I2C bus. 

  i2cDev: >= 0
 i2cAddr: 0-0x7F
i2cFlags: 0

If OK returns a handle (>= 0).

On failure returns a negative error code.

No flags are currently defined. This parameter should be set to zero.

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
i2cReg (8 bits): Command byte, 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

This closes the I2C device. 

handle: >= 0 (as returned by lgI2cOpen)

If OK returns 0.

On failure returns a negative error code.

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

handle: >= 0 (as returned by lgI2cOpen)
bitVal: 0-1, the value to write

If OK returns 0.

On failure returns a negative error code.

Quick command. SMBus 2.0 5.5.1

S Addr bit [A] P

This sends a single byte to the device. 

 handle: >= 0 (as returned by lgI2cOpen)
byteVal: 0-0xFF, the value to write

If OK returns 0.

On failure returns a negative error code.

Send byte. SMBus 2.0 5.5.2

S Addr Wr [A] bVal [A] P

This reads a single byte from the device. 

handle: >= 0 (as returned by lgI2cOpen)

If OK returns the byte read (0-255).

On failure returns a negative error code.

Receive byte. SMBus 2.0 5.5.3

S Addr Rd [A] [Data] NA P

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

 handle: >= 0 (as returned by lgI2cOpen)
 i2cReg: 0-255, the register to write
byteVal: 0-0xFF, the value to write

If OK returns 0.

On failure returns a negative error code.

Write byte. SMBus 2.0 5.5.4

S Addr Wr [A] i2cReg [A] bVal [A] P

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

 handle: >= 0 (as returned by lgI2cOpen)
 i2cReg: 0-255, the register to write
wordVal: 0-0xFFFF, the value to write

If OK returns 0.

On failure returns a negative error code.

Write word. SMBus 2.0 5.5.4

S Addr Wr [A] i2cReg [A] wValLow [A] wValHigh [A] P

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

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to read

If OK returns the byte read (0-255).

On failure returns a negative error code.

Read byte. SMBus 2.0 5.5.5

S Addr Wr [A] i2cReg [A] S Addr Rd [A] [Data] NA P

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

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to read

If OK returns the word read (0-65535).

On failure returns a negative error code.

Read word. SMBus 2.0 5.5.5

S Addr Wr [A] i2cReg [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P

This writes 16 bits of data to the specified register of the device and reads 16 bits of data in return. 

 handle: >= 0 (as returned by lgI2cOpen)
 i2cReg: 0-255, the register to write/read
wordVal: 0-0xFFFF, the value to write

If OK returns the word read (0-65535).

On failure returns a negative error code.

Process call. SMBus 2.0 5.5.6

S Addr Wr [A] i2cReg [A] wValLow [A] wValHigh [A]
   S Addr Rd [A] [DataLow] A [DataHigh] NA P

This writes up to 32 bytes to the specified register of the device. 

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to write
 txBuf: an array with the data to send
 count: 1-32, the number of bytes to write

If OK returns 0.

On failure returns a negative error code.

Block write. SMBus 2.0 5.5.7

S Addr Wr [A] i2cReg [A] count [A]
   txBuf0 [A] txBuf1 [A] ... [A] txBufn [A] P

This reads a block of up to 32 bytes from the specified register of the device. 

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to read
 rxBuf: an array to receive the read data

The amount of returned data is set by the device.

If OK returns the count of bytes read (0-32) and updates rxBuf.

On failure returns a negative error code.

Block read. SMBus 2.0 5.5.7

S Addr Wr [A] i2cReg [A]
   S Addr Rd [A] [Count] A [rxBuf0] A [rxBuf1] A ... A [rxBufn] NA P

This writes data bytes to the specified register of the device and reads a device specified number of bytes of data in return. 

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to write/read
 ioBuf: an array with the data to send and to receive the read data
 count: 1-32, the number of bytes to write

If OK returns the count of bytes read (0-32) and updates ioBuf.

On failure returns a negative error code.

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] i2cReg [A] count [A] ioBuf0 [A] ... ioBufn [A]
   S Addr Rd [A] [Count] A [ioBuf0] A ... [ioBufn] A P

This reads count bytes from the specified register of the device. The count may be 1-32. 

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to read
 rxBuf: an array to receive the read data
 count: 1-32, the number of bytes to read

If OK returns the count of bytes read (0-32) and updates rxBuf.

On failure returns a negative error code.

S Addr Wr [A] i2cReg [A]
   S Addr Rd [A] [rxBuf0] A [rxBuf1] A ... A [rxBufn] NA P

This writes 1 to 32 bytes to the specified register of the device. 

handle: >= 0 (as returned by lgI2cOpen)
i2cReg: 0-255, the register to write
 txBuf: the data to write
 count: 1-32, the number of bytes to write

If OK returns 0.

On failure returns a negative error code.

S Addr Wr [A] i2cReg [A] txBuf0 [A] txBuf1 [A] ... [A] txBufn [A] P

This reads count bytes from the raw device into rxBuf. 

handle: >= 0 (as returned by lgI2cOpen)
 rxBuf: an array to receive the read data bytes
 count: >0, the number of bytes to read

If OK returns count (>0) and updates rxBuf.

On failure returns a negative error code.

S Addr Rd [A] [rxBuf0] A [rxBuf1] A ... A [rxBufn] NA P

This writes count bytes from txBuf to the raw device. 

handle: >= 0 (as returned by lgI2cOpen)
 txBuf: an array containing the data bytes to write
 count: >0, the number of bytes to write

If OK returns 0.

On failure returns a negative error code.

S Addr Wr [A] txBuf0 [A] txBuf1 [A] ... [A] txBufn [A] P

This function executes multiple I2C segments in one transaction by calling the I2C_RDWR ioctl. 

handle: >= 0 (as returned by lgI2cOpen)
  segs: an array of I2C segments
 count: >0, the number of I2C segments

If OK returns the number of segments executed.

On failure returns a negative error code.

This function executes a sequence of I2C operations. The operations to be performed are specified by the contents of txBuf which contains the concatenated command codes and associated data. 

  handle: >= 0 (as returned by lgI2cOpen)
   txBuf: pointer to the concatenated I2C commands, see below
 txCount: size of command buffer
   rxBuf: pointer to buffer to hold returned data
 rxCount: size of receive buffer

If OK returns the count of bytes read (which may be 0) and updates rxBuf.

On failure returns a negative error code.

The following command codes are supported:

Name Cmd & Data Meaning
End 0 No more commands
Escape 1 Next P is two bytes
Address 2 P Set I2C address to P
Flags 3 lsb msb Set I2C flags to lsb + (msb << 8)
Read 4 P Read P bytes of data
Write 5 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 rxBuf.

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


2 0x53  5 1 0x32  4 6
2 0x1E  5 1 0x03  4 6
2 0x68  5 1 0x1B  4 8
0

This function opens a serial device at a specified baud rate and with specified flags. 

  serDev: the serial device to open
 serBaud: the baud rate in bits per second, see below
serFlags: 0

If OK returns a handle (>= 0).

On failure returns a negative error code.

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.

This function closes the serial device. 

handle: >= 0 (as returned by lgSerialOpen)

If OK returns 0.

On failure returns a negative error code.

This function writes the byte to the serial device. 

 handle: >= 0 (as returned by lgSerialOpen)
byteVal: the byte to write.

If OK returns 0.

On failure returns a negative error code.

This function reads a byte from the serial device. 

handle: >= 0 (as returned by lgSerialOpen)

If OK returns the byte read (0-255).

On failure returns a negative error code.

This function writes count bytes from txBuf to the the serial device. 

handle: >= 0 (as returned by lgSerialOpen)
 txBuf: the array of bytes to write
 count: the number of bytes to write

If OK returns 0.

On failure returns a negative error code.

This function reads up count bytes from the the serial device and writes them to rxBuf. 

handle: >= 0 (as returned by lgSerialOpen)
 rxBuf: an array to receive the read data
 count: the maximum number of bytes to read

If OK returns the count of bytes read (>= 0) and updates rxBuf.

On failure returns a negative error code.

This function returns the count of bytes available to be read from the device. 

handle: >= 0 (as returned by lgSerialOpen)

If OK returns the count of bytes available(>= 0).

On failure returns a negative error code.

This function returns a handle for the SPI device on the channel. 

  spiDev: >= 0
 spiChan: >= 0
 spiBaud: the SPI speed to set in bits per second
spiFlags: see below

If OK returns a handle (>= 0).

On failure returns a negative error code.

The flags may be used to modify the default behaviour.

spiFlags consists of the least significant 2 bits.

1  0
m  m

mm defines the SPI mode.

Mode POL PHA
 0    0   0
 1    0   1
 2    1   0
 3    1   1

The other bits in flags should be set to zero.

This functions closes the SPI device. 

handle: >= 0 (as returned by lgSpiOpen)

If OK returns 0.

On failure returns a negative error code.

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

handle: >= 0 (as returned by lgSpiOpen)
 rxBuf: an array to receive the read data bytes
 count: the number of bytes to read

If OK returns the count of bytes read and updates rxBuf.

On failure returns a negative error code.

This function writes count bytes of data from txBuf to the SPI device. 

handle: >= 0 (as returned by lgSpiOpen)
 txBuf: the data bytes to write
 count: the number of bytes to write

If OK returns the count of bytes written.

On failure returns a negative error code.

This function transfers count bytes of data from txBuf to the SPI device. Simultaneously count bytes of data are read from the device and placed in rxBuf. 

handle: >= 0 (as returned by lgSpiOpen)
 txBuf: the data bytes to write
 rxBuf: the received data bytes
 count: the number of bytes to transfer

If OK returns the count of bytes transferred and updates rxBuf.

On failure returns a negative error code.

Starts a new thread of execution with f as the main routine. 

       f: the main function for the new thread
userdata: a pointer to arbitrary user data

If OK returns a pointer to a pthread_t.

On failure returns NULL.

The function is passed the single argument arg.

The thread can be cancelled by passing the pointer to pthread_t to lgThreadStop.

Example

#include <stdio.h>
#include <unistd.h>
#include <lgpio.h>


void *myfunc(void *arg)
{
   while (1)
   {
      printf("%s0, (char *)arg);
      sleep(1);
   }
}


int main(int argc, char *argv[])
{
   pthread_t *p1, *p2, *p3;


   p1 = lgThreadStart(myfunc, "thread 1"); sleep(3);


   p2 = lgThreadStart(myfunc, "thread 2"); sleep(3);


   p3 = lgThreadStart(myfunc, "thread 3"); sleep(3);


   lgThreadStop(p3); sleep(3);


   lgThreadStop(p2); sleep(3);


   lgThreadStop(p1); sleep(3);
}

Cancels the thread pointed at by pth. 

pth: a thread pointer (as returned by lgThreadStart)

No value is returned.

The thread to be stopped should have been started with lgThreadStart.

Returns the current timestamp.

The timestamp is the number of nanoseconds since the epoch (start of 1970).

Returns the current time.

The time is the number of seconds since the epoch (start of 1970).

Sleeps for the specified number of seconds. 

sleepSecs: how long to sleep in seconds

Copies the host name of the machine running the lgpio library to the supplied buffer. Up to count characters are copied. 

rxBuf: a buffer to receive the host name
count: the size of the rxBuf

If OK returns the count of bytes copied and updates rxBuf.

On failure returns a negative error code.

Returns the lgpiolibrary version number.

Get an internal configuration value. 

 cfgId: the item.
cfgVal: a variable to receive the returned value

If OK returns 0 and updates cfgVal.

On failure returns a negative error code.

Set an internal configuration value. 

 cfgId: the item
cfgVal: the value to set

If OK returns 0.

On failure returns a negative error code.

Returns the error text for an error code. 

error: the error code

Sets the library working directory.

This function has no affect if the working directory has already been set.

dirPath: the directory to set as the working directory

If dirPath does not start with a / the directory is relative to the library launch directory.

Returns the library working directory.

A value of 0 or 1.

An 8-bit byte value.

An alerts callback function.

A number identifying a configuration item. 

LG_CFG_ID_DEBUG_LEVEL 0
LG_CFG_ID_MIN_DELAY   1

The value of a configuration item.

*cfgVal
The value of a configuration item.

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

A pointer to a lgChipInfo_t object.

The number of items.

The debounce time in microseconds.

*dirPath
A directory path which.

A floating point number.

The type of GPIO edge to generate an alert. See lgGpioClaimAlert.

LG_RISING_EDGE
LG_FALLING_EDGE
LG_BOTH_EDGES

An error code. All error codes are negative.

A function.

A floating point number

A GPIO number, the offset of the GPIO from the base of the gpiochip. Offsets start at 0.

The device number of a gpiochip.

*gpios
An array of GPIO numbers.

*gpiouser
A string of up to 32 characters denoting the user of a GPIO.

A 64-bit value used to set the levels of a group.

Set bit x to set GPIO x of the group high.

Clear bit x to set GPIO x of the group low.

*groupBits
A 64-bit value denoting the levels of a group.

If bit x is set then GPIO x of the group is high.

A 64-bit value used to determine which members of a group should be updated.

Set bit x to update GPIO x of the group.

Clear bit x to leave GPIO x of the group unaltered.

A number referencing an object opened by one of

lgGpiochipOpen
lgI2cOpen
lgNotifyOpen
lgSerialOpen
lgSpiOpen

The address of a device on the I2C bus.

An I2C device number.

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

A register of an I2C device.

A whole number, negative or positive.

*ioBuf
A pointer to a buffer used to hold data to send and the data received.

A type of transmission: PWM or wave.

A GPIO level (0 or 1).

*levels
An array of GPIO levels.

line flags for the GPIO.

The following values may be or'd to form the value.

LG_SET_ACTIVE_LOW
LG_SET_OPEN_DRAIN
LG_SET_OPEN_SOURCE
LG_SET_PULL_UP
LG_SET_PULL_DOWN
LG_SET_PULL_NONE

A pointer to a lgChipInfo_t object. 

typedef struct lgChipInfo_s
{
   uint32_t lines;                // number of GPIO
   char name[LG_GPIO_NAME_LEN];   // Linux name
   char label[LG_GPIO_LABEL_LEN]; // functional name
} lgChipInfo_t, *lgChipInfo_p;
    

typedef struct lgGpioAlert_s
{
   lgGpioReport_t report;
   int nfyHandle;
} lgGpioAlert_t, *lgGpioAlert_p;

See lgGpioReport_t.

typedef void (*lgGpioAlertsFunc_t)
   (int num_alerts, lgGpioAlert_p alerts, void *userdata);

See lgGpioAlert_t.

typedef struct
{
   uint64_t timestamp; // alert time in nanoseconds
   uint8_t chip;       // gpiochip device number
   uint8_t gpio;       // offset into gpio device
   uint8_t level;      // 0=low, 1=high, 2=watchdog
   uint8_t flags;      // none defined, ignore report if non-zero
} lgGpioReport_t;
    

typedef struct
{
   uint16_t addr;  // slave address
   uint16_t flags;
   uint16_t len;   // msg length
   uint8_t  *buf;  // pointer to msg data
} lgI2cMsg_t;

A pointer to a lgLineInfo_t object. 

typedef struct lgLine_s
{
   uint32_t offset;               // GPIO number
   uint32_t lFlags;
   char name[LG_GPIO_NAME_LEN];   // GPIO name
   char user[LG_GPIO_USER_LEN];   // user
} lgLineInfo_t, *lgLineInfo_p;

A pointer to a lgPulse_t object. 

typedef struct lgPulse_s
{
   uint64_t bits;
   uint64_t mask;
   int64_t delay;
} lgPulse_t, *lgPulse_p;
    

typedef void *(lgThreadFunc_t) (void *);

A pointer to a lgLineInfo_t object.

This associates a notification with a GPIO alert.

*pth
A thread identifier, returned by lgGpioStartThread.

A thread identifier.

The number of PWM pulses to generate. A value of 0 means infinite.

The off period for a PWM pulse in microseconds.

The offset in microseconds from the nominal PWM pulse start.

The on period for a PWM pulse in microseconds.

An pointer to an array of lgPulse_t objects.

Servo pulse width

The number of PWM pulses to generate. A value of 0 means infinite.

PWM duty cycle %

PWM frequency

The offset in microseconds from the nominal PWM pulse start.

*rxBuf
A pointer to a buffer used to receive data.

The size of an input buffer.

*segs
An array of segments which make up a combined I2C transaction.

The speed of serial communication in bits per second.

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

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

The number of servo pulses to generate. A value of 0 means infinite.

Servo pulse frequency

The offset in microseconds from the nominal servo pulse start.

The number of seconds to sleep (may be fractional).

The speed of serial communication in bits per second.

A SPI channel, >= 0.

A SPI device, >= 0.

See lgSpiOpen.

*txBuf
An pointer to a buffer of data to transmit.

The size of an output buffer.

A 64-bit unsigned value.

*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);

Denoting no parameter is required.

The watchdog time in microseconds.

A 16-bit value. 

LG_OKAY                   0 // No error
LG_INIT_FAILED           -1 // initialisation failed
LG_BAD_MICROS            -2 // micros not 0-999999
LG_BAD_PATHNAME          -3 // can not open pathname
LG_NO_HANDLE             -4 // no handle available
LG_BAD_HANDLE            -5 // unknown handle
LG_BAD_SOCKET_PORT       -6 // socket port not 1024-32000
LG_NOT_PERMITTED         -7 // GPIO operation not permitted
LG_SOME_PERMITTED        -8 // one or more GPIO not permitted
LG_BAD_SCRIPT            -9 // invalid script
LG_BAD_TX_TYPE          -10 // bad tx type for GPIO and group
LG_GPIO_IN_USE          -11 // GPIO already in use
LG_BAD_PARAM_NUM        -12 // script parameter id not 0-9
LG_DUP_TAG              -13 // script has duplicate tag
LG_TOO_MANY_TAGS        -14 // script has too many tags
LG_BAD_SCRIPT_CMD       -15 // illegal script command
LG_BAD_VAR_NUM          -16 // script variable id not 0-149
LG_NO_SCRIPT_ROOM       -17 // no more room for scripts
LG_NO_MEMORY            -18 // can not allocate temporary memory
LG_SOCK_READ_FAILED     -19 // socket read failed
LG_SOCK_WRIT_FAILED     -20 // socket write failed
LG_TOO_MANY_PARAM       -21 // too many script parameters (> 10)
LG_SCRIPT_NOT_READY     -22 // script initialising
LG_BAD_TAG              -23 // script has unresolved tag
LG_BAD_MICS_DELAY       -24 // bad MICS delay (too large)
LG_BAD_MILS_DELAY       -25 // bad MILS delay (too large)
LG_I2C_OPEN_FAILED      -26 // can not open I2C device
LG_SERIAL_OPEN_FAILED   -27 // can not open serial device
LG_SPI_OPEN_FAILED      -28 // can not open SPI device
LG_BAD_I2C_BUS          -29 // bad I2C bus
LG_BAD_I2C_ADDR         -30 // bad I2C address
LG_BAD_SPI_CHANNEL      -31 // bad SPI channel
LG_BAD_I2C_FLAGS        -32 // bad I2C open flags
LG_BAD_SPI_FLAGS        -33 // bad SPI open flags
LG_BAD_SERIAL_FLAGS     -34 // bad serial open flags
LG_BAD_SPI_SPEED        -35 // bad SPI speed
LG_BAD_SERIAL_DEVICE    -36 // bad serial device name
LG_BAD_SERIAL_SPEED     -37 // bad serial baud rate
LG_BAD_FILE_PARAM       -38 // bad file parameter
LG_BAD_I2C_PARAM        -39 // bad I2C parameter
LG_BAD_SERIAL_PARAM     -40 // bad serial parameter
LG_I2C_WRITE_FAILED     -41 // i2c write failed
LG_I2C_READ_FAILED      -42 // i2c read failed
LG_BAD_SPI_COUNT        -43 // bad SPI count
LG_SERIAL_WRITE_FAILED  -44 // ser write failed
LG_SERIAL_READ_FAILED   -45 // ser read failed
LG_SERIAL_READ_NO_DATA  -46 // ser read no data available
LG_UNKNOWN_COMMAND      -47 // unknown command
LG_SPI_XFER_FAILED      -48 // spi xfer/read/write failed
LG_BAD_POINTER          -49 // bad (NULL) pointer
LG_MSG_TOOBIG           -50 // socket/pipe message too big
LG_BAD_MALLOC_MODE      -51 // bad memory allocation mode
LG_TOO_MANY_SEGS        -52 // too many I2C transaction segments
LG_BAD_I2C_SEG          -53 // an I2C transaction segment failed
LG_BAD_SMBUS_CMD        -54 // SMBus command not supported by driver
LG_BAD_I2C_WLEN         -55 // bad I2C write length
LG_BAD_I2C_RLEN         -56 // bad I2C read length
LG_BAD_I2C_CMD          -57 // bad I2C command
LG_FILE_OPEN_FAILED     -58 // file open failed
LG_BAD_FILE_MODE        -59 // bad file mode
LG_BAD_FILE_FLAG        -60 // bad file flag
LG_BAD_FILE_READ        -61 // bad file read
LG_BAD_FILE_WRITE       -62 // bad file write
LG_FILE_NOT_ROPEN       -63 // file not open for read
LG_FILE_NOT_WOPEN       -64 // file not open for write
LG_BAD_FILE_SEEK        -65 // bad file seek
LG_NO_FILE_MATCH        -66 // no files match pattern
LG_NO_FILE_ACCESS       -67 // no permission to access file
LG_FILE_IS_A_DIR        -68 // file is a directory
LG_BAD_SHELL_STATUS     -69 // bad shell return status
LG_BAD_SCRIPT_NAME      -70 // bad script name
LG_CMD_INTERRUPTED      -71 // Python socket command interrupted
LG_BAD_EVENT_REQUEST    -72 // bad event request
LG_BAD_GPIO_NUMBER      -73 // bad GPIO number
LG_BAD_GROUP_SIZE       -74 // bad group size
LG_BAD_LINEINFO_IOCTL   -75 // bad lineinfo IOCTL
LG_BAD_READ             -76 // bad GPIO read
LG_BAD_WRITE            -77 // bad GPIO write
LG_CANNOT_OPEN_CHIP     -78 // can not open gpiochip
LG_GPIO_BUSY            -79 // GPIO busy
LG_GPIO_NOT_ALLOCATED   -80 // GPIO not allocated
LG_NOT_A_GPIOCHIP       -81 // not a gpiochip
LG_NOT_ENOUGH_MEMORY    -82 // not enough memory
LG_POLL_FAILED          -83 // GPIO poll failed
LG_TOO_MANY_GPIOS       -84 // too many GPIO
LG_UNEGPECTED_ERROR     -85 // unexpected error
LG_BAD_PWM_MICROS       -86 // bad PWM micros
LG_NOT_GROUP_LEADER     -87 // GPIO not the group leader
LG_SPI_IOCTL_FAILED     -88 // SPI iOCTL failed
LG_BAD_GPIOCHIP         -89 // bad gpiochip
LG_BAD_CHIPINFO_IOCTL   -90 // bad chipinfo IOCTL
LG_BAD_CONFIG_FILE      -91 // bad configuration file
LG_BAD_CONFIG_VALUE     -92 // bad configuration value
LG_NO_PERMISSIONS       -93 // no permission to perform action
LG_BAD_USERNAME         -94 // bad user name
LG_BAD_SECRET           -95 // bad secret for user
LG_TX_QUEUE_FULL        -96 // TX queue full
LG_BAD_CONFIG_ID        -97 // bad configuration id
LG_BAD_DEBOUNCE_MICS    -98 // bad debounce microseconds
LG_BAD_WATCHDOG_MICS    -99 // bad watchdog microseconds
LG_BAD_SERVO_FREQ      -100 // bad servo frequency
LG_BAD_SERVO_WIDTH     -101 // bad servo pulsewidth
LG_BAD_PWM_FREQ        -102 // bad PWM frequency
LG_BAD_PWM_DUTY        -103 // bad PWM dutycycle
LG_GPIO_NOT_AN_OUTPUT  -104 // GPIO not set as an output
LG_INVALID_GROUP_ALERT -105 // can not set a group to alert

rgpiod(1), rgs(1), rgpio(3)