| lgpio(3) | lg archive | lgpio(3) |
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
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
}
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
}
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))
}
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))
}
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.
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");
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);
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);
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);
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);
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
}
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
}
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
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
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
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
}
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);
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
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.
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.
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);
}
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);
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
}
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
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
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)
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)
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.
}
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);
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);
handle: >= 0 (as returned by lgNotifyOpen)
If OK returns 0.
On failure returns a negative error code.
Example
lgNotifyClose(h);
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
handle: >= 0 (as returned by lgI2cOpen)
If OK returns 0.
On failure returns a negative error code.
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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.
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
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.
handle: >= 0 (as returned by lgSerialOpen)
If OK returns 0.
On failure returns a negative error code.
handle: >= 0 (as returned by lgSerialOpen)
byteVal: the byte to write.
If OK returns 0.
On failure returns a negative error code.
handle: >= 0 (as returned by lgSerialOpen)
If OK returns the byte read (0-255).
On failure returns a negative error code.
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.
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.
handle: >= 0 (as returned by lgSerialOpen)
If OK returns the count of bytes available(>= 0).
On failure returns a negative error code.
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.
handle: >= 0 (as returned by lgSpiOpen)
If OK returns 0.
On failure returns a negative error code.
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.
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.
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.
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);
}
pth: a thread pointer (as returned by lgThreadStart)
No value is returned.
The thread to be stopped should have been started with lgThreadStart.
The timestamp is the number of nanoseconds since the epoch (start of 1970).
The time is the number of seconds since the epoch (start of 1970).
sleepSecs: how long to sleep in seconds
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.
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.
cfgId: the item
cfgVal: the value to set
If OK returns 0.
On failure returns a negative error code.
error: the error code
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.
LG_CFG_ID_DEBUG_LEVEL 0
LG_CFG_ID_MIN_DELAY 1
The type of GPIO edge to generate an alert. See lgGpioClaimAlert.
LG_RISING_EDGE
LG_FALLING_EDGE
LG_BOTH_EDGES
Set bit x to set GPIO x of the group high.
Clear bit x to set GPIO x of the group low.
If bit x is set then GPIO x of the group is high.
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
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
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;
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;
typedef struct lgPulse_s
{ uint64_t bits; uint64_t mask; int64_t delay;
} lgPulse_t, *lgPulse_p;
typedef void *(lgThreadFunc_t) (void *);
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);
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)
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