Edge1 GPIO Interrupts

The page leads you to use GPIO interrupts with the GPIO number test program on Khadas SBC.

Connect the physical pins PIN20 and PIN15 by using a DuPont line.

Get GPIOH_6 number

Refer to 40-Pin Header, the GPIO number you get is 433.

Export GPIO

$ echo 433 | sudo tee /sys/class/gpio/export

Get demo source code

gpio_interrupts.c

// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
/*
 * Copyright (c) 2022 Wesion Technology Co., Ltd.
 *
 * Author: Yan <yan-wyb@foxmail.com> 
 *
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <poll.h>
 
#define SYSFS_GPIO_DIR  "/sys/class/gpio"
#define MAX_BUF     255
 
int gpio_export(unsigned int gpio){
 
    int fd, len;
    char buf[MAX_BUF];
 
    fd = open(SYSFS_GPIO_DIR "/export", O_WRONLY);
 
    if (fd < 0) {
        fprintf(stderr, "Can't export GPIO %d pin: %s\n", gpio, strerror(errno));
        return fd;
    }
 
    len = snprintf(buf, sizeof(buf), "%d", gpio);
    write(fd, buf, len);
    close(fd);
 
    return 0;
}
 
int gpio_unexport(unsigned int gpio){
 
    int fd, len;
    char buf[MAX_BUF];
 
    fd = open(SYSFS_GPIO_DIR "/unexport", O_WRONLY);
 
    if (fd < 0) {
        fprintf(stderr, "Can't unexport GPIO %d pin: %s\n", gpio, strerror(errno));
        return fd;
    }
 
    len = snprintf(buf, sizeof(buf), "%d", gpio);
    write(fd, buf, len);
    close(fd);
 
    return 0;
}
 
int gpio_set_edge(unsigned int gpio, char *edge){
 
    int fd, len;
    char buf[MAX_BUF];
 
    len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/edge", gpio);
 
    fd = open(buf, O_WRONLY);
 
    if (fd < 0) {
        fprintf(stderr, "Can't set GPIO %d pin edge: %s\n", gpio, strerror(errno));
        return fd;
    }
 
    write(fd, edge, strlen(edge)+1);
    close(fd);
 
    return 0;
}
 
int gpio_set_pull(unsigned int gpio, char *pull){
 
    int fd, len;
    char buf[MAX_BUF];
 
    len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/pull", gpio);
 
    fd = open(buf, O_WRONLY);
 
    if (fd < 0) {
        fprintf(stderr, "Can't set GPIO %d pin pull: %s\n", gpio, strerror(errno));
        return fd;
    }
 
    write(fd, pull, strlen(pull)+1);
    close(fd);
 
    return 0;
}
 
int main(int argc, char *argv[])
{
    struct pollfd fdset[2];
    int fd, ret, gpio;
    char buf[MAX_BUF];
 
    if (argc < 3 || argc > 4)   {
        fprintf(stdout, "usage : sudo sysfs_irq_test <gpio> <edge> [pull]\n");
        fflush(stdout);
        return  -1;
    }
 
    gpio = atoi(argv[1]);
    if (gpio_export(gpio))  {
        fprintf(stdout, "error : export %d\n", gpio);
        fflush(stdout);
        return  -1;
    }
 
    if (gpio_set_edge(gpio, argv[2])) {
        fprintf(stdout, "error : edge %s\n", argv[2]);
        fflush(stdout);
        return  -1;
    }
 
    if (argv[3] && gpio_set_pull(gpio, argv[3])) {
        fprintf(stdout, "error : pull %s\n", argv[3]);
        fflush(stdout);
        return  -1;
    }
 
    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
    fd = open(buf, O_RDWR);
    if (fd < 0)
        goto out;
 
    while (1) {
        memset(fdset, 0, sizeof(fdset));
        fdset[0].fd = STDIN_FILENO;
        fdset[0].events = POLLIN;
        fdset[1].fd = fd;
        fdset[1].events = POLLPRI;
        ret = poll(fdset, 2, 3*1000);
 
        if (ret < 0) {
            perror("poll");
            break;
        }
 
        fprintf(stderr, ".");
 
        if (fdset[1].revents & POLLPRI) {
            char c;
            (void)read (fd, &c, 1) ;
            lseek (fd, 0, SEEK_SET) ;
            fprintf(stderr, "\nGPIO %d interrupt occurred!\n", gpio);
        }
 
        if (fdset[0].revents & POLLIN)
            break;
 
        fflush(stdout);
    }
 
    close(fd);
out:
    if (gpio_unexport(gpio))    {
        fprintf(stdout, "error : unexport %d\n", gpio);
        fflush(stdout);
    }
 
    return 0;
 }

Compile the source code

$ gcc -o gpio_interrupts gpio_interrupts.c

The test code running format is as follows:

$ sudo ./gpio_interrupts <edge> [pull]

Run test:

$ sudo ./gpio_interrupts rising down
.
GPIO 433 interrupt occurred!
..
GPIO 433 interrupt occurred!
.
GPIO 433 interrupt occurred!
.
GPIO 433 interrupt occurred!