C/C++ GPIO Development

This document describes the recommended C/C++ GPIO workflow on Quectel Pi M1/L1. The checked development board image supports libgpiod v1.6.3. lgpio libraries and lgpio.h were not detected, so libgpiod is the default path.

Prepare Environment

sudo apt update
sudo apt install -y build-essential gpiod libgpiod-dev
gpiodetect --version
gpiodetect

Item	Description
Recommended library	libgpiod
Link flag	-lgpiod
Main controller	Currently verified as /dev/gpiochip0

Read Example

#include <gpiod.h>
#include <stdio.h>

int main(void)
{
    struct gpiod_chip *chip = gpiod_chip_open_by_name("gpiochip0");
    struct gpiod_line *line = gpiod_chip_get_line(chip, 36);

    gpiod_line_request_input(line, "m1-gpio-input");
    printf("value=%d\n", gpiod_line_get_value(line));

    gpiod_line_release(line);
    gpiod_chip_close(chip);
    return 0;
}

gcc -Wall -o gpio_input gpio_input.c -lgpiod
sudo ./gpio_input

Output Example

#include <gpiod.h>
#include <unistd.h>

int main(void)
{
    struct gpiod_chip *chip = gpiod_chip_open_by_name("gpiochip0");
    struct gpiod_line *line = gpiod_chip_get_line(chip, 36);

    gpiod_line_request_output(line, "m1-gpio-output", 1);
    sleep(1);
    gpiod_line_set_value(line, 0);

    gpiod_line_release(line);
    gpiod_chip_close(chip);
    return 0;
}

gcc -Wall -o gpio_output gpio_output.c -lgpiod
sudo ./gpio_output

Notes

• Confirm the real line offset from the M1 pin definition before wiring.

• If runtime access fails, check line usage with gpioinfo /dev/gpiochip0.

• If gpiod.h is missing, install libgpiod-dev.