Using pigpiod

The pigpio library described earlier (see Using pigpio) can be launched and used as a daemon.

Usage

To launch the daemon, use the following command:

ubuntu@rpi:~$ sudo pigpiod

To stop the daemon, stop the previous process:

ubuntu@rpi:~$ sudo killall pigpiod

To interface with pigpiod you need to use a different set of functions, declared in pigpiod_if2.h.

To compile code that interfaces with pigpiod, link with libpigpiod_if2 instead of libpigpio, as follows:

gcc -Wall -pthread -o io1212-4 io1212-4.c -lpigpiod_if2 -lrt

Example 1: Blink

An equivalent to the first example of the non-daemon pigpio library (see Example 1: Blink) can be created by calling the pigpiod_if2 interface instead of pigpio.

#include <unistd.h>

#include <pigpiod_if2.h>

#define Output_1 4
#define Output_2 5
#define Output_3 6
#define Output_4 7
#define Output_5 8
#define Output_6 9
#define Output_7 10
#define Output_8 11
#define Output_9 12
#define Output_10 13
#define Output_11 14
#define Output_12 15

#define Input_1 16
#define Input_2 17
#define Input_3 18
#define Input_4 19
#define Input_5 20
#define Input_6 21
#define Input_7 22
#define Input_8 23
#define Input_9 24
#define Input_10 25
#define Input_11 26
#define Input_12 27

char *optHost   = NULL;
char *optPort   = NULL;

int main(int argc, char *argv[])
{
   int pi;

   pi = pigpio_start(optHost, optPort);

   if (pi<0) return 1;

   set_mode(pi, Output_1, PI_OUTPUT);
   set_mode(pi, Output_2, PI_OUTPUT);
   set_mode(pi, Output_3, PI_OUTPUT);
   set_mode(pi, Output_4, PI_OUTPUT);
   set_mode(pi, Output_5, PI_OUTPUT);
   set_mode(pi, Output_6, PI_OUTPUT);
   set_mode(pi, Output_7, PI_OUTPUT);
   set_mode(pi, Output_8, PI_OUTPUT);
   set_mode(pi, Output_9, PI_OUTPUT);
   set_mode(pi, Output_10, PI_OUTPUT);
   set_mode(pi, Output_11, PI_OUTPUT);
   set_mode(pi, Output_12, PI_OUTPUT);

   set_mode(pi, Input_1, PI_INPUT);
   set_mode(pi, Input_2, PI_INPUT);
   set_mode(pi, Input_3, PI_INPUT);
   set_mode(pi, Input_4, PI_INPUT);
   set_mode(pi, Input_5, PI_INPUT);
   set_mode(pi, Input_6, PI_INPUT);
   set_mode(pi, Input_7, PI_INPUT);
   set_mode(pi, Input_8, PI_INPUT);
   set_mode(pi, Input_9, PI_INPUT);
   set_mode(pi, Input_10, PI_INPUT);
   set_mode(pi, Input_11, PI_INPUT);
   set_mode(pi, Input_12, PI_INPUT);

   set_pull_up_down(pi, Input_1, PI_PUD_OFF);
   set_pull_up_down(pi, Input_2, PI_PUD_OFF);
   set_pull_up_down(pi, Input_3, PI_PUD_OFF);
   set_pull_up_down(pi, Input_4, PI_PUD_OFF);
   set_pull_up_down(pi, Input_5, PI_PUD_OFF);
   set_pull_up_down(pi, Input_6, PI_PUD_OFF);
   set_pull_up_down(pi, Input_7, PI_PUD_OFF);
   set_pull_up_down(pi, Input_8, PI_PUD_OFF);
   set_pull_up_down(pi, Input_9, PI_PUD_OFF);
   set_pull_up_down(pi, Input_10, PI_PUD_OFF);
   set_pull_up_down(pi, Input_11, PI_PUD_OFF);
   set_pull_up_down(pi, Input_12, PI_PUD_OFF);

   int count = 30;

   while(count) {
        gpio_write(pi, Output_1, 1);
        sleep(1);
        gpio_write(pi, Output_1, 0);
        sleep(1);
        count--;
   }

   pigpio_stop(pi);
}

Example 2: Using inputs

An example of how to read an input using gpio_read() can be tested by substituting lines 81-89 above with the following snippet.

   int count = 20;
   int state = gpio_read(pi, Input_1);
   
   while(count) {
        while(state == gpio_read(pi, Input_1));
        state = gpio_read(pi, Input_1);
        gpio_write(pi, Output_1, state);
        sleep(1);
        count--;
   }

   gpio_write(pi, Output_1, 0);