BeagleY-AI and GPIO Pins

General Discussion
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31

Hi Seth,

I tried your c code that you posted on the 2nd of November, and it’s basicly working fine. I had to fix some minor issues, my changes are shown below.
Checking the pins, I could see the rising and falling levels on the Direction, Step and Enable pins - pins 35, 33 and 32 on the 40 pin header.

This means that the gpios and libgpiod are working as they should.

Double check the sense of your outputs - in particular the enable signal is active low.

I’m on Debian Bookworm Xfce Image 2024-06-12

/*
 * cc gpio_test.c -lgpiod -o gpio_test
 */

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


#ifndef CONSUMER
#define CONSUMER  "Consumer"
#endif


int main(int argc, char **argv)
{
  const char *chipname = "gpiochip2";
  unsigned int line_num1 = 18;		// Direction
  unsigned int line_num2 = 12;		// Step
  unsigned int line_num3 = 16;		// Enable
  unsigned int val;
  struct gpiod_chip *chip;
  struct gpiod_line *line1;
  struct gpiod_line *line2;
  struct gpiod_line *line3;
  int ret1, ret2, ret3;

  chip = gpiod_chip_open_by_name(chipname);
  if (!chip) {
    perror("The opening is failing...\n");
    goto end;
  }

  line1 = gpiod_chip_get_line(chip, line_num1);
  if (!line1) {
    perror("Get line 1 failed\n");
    goto close_chip;
  }

  line2 = gpiod_chip_get_line(chip, line_num2);
  if (!line2) {
    perror("Get line 2 failed\n");
    goto close_chip;
  }

  line3 = gpiod_chip_get_line(chip, line_num3);
  if (!line3) {
    perror("Get line 3 failed\n");
    goto close_chip;
  }
  printf("3 lines got\n");

  ret1 = gpiod_line_request_output(line1, CONSUMER, 0);
  if (ret1 < 0) {
    perror("Request line 1 as output failed\n");
    goto release_line;
  }

  ret2 = gpiod_line_request_output(line2, CONSUMER, 0);
  if (ret2 < 0) {
    perror("Request line 2 as output failed\n");
    goto release_line;
  }

  ret3 = gpiod_line_request_output(line3, CONSUMER, 0);
  if (ret3 < 0) {
    perror("Request line 3 as output failed\n");
    goto release_line;
  }
  printf("3 lines as output\n");

  gpiod_line_set_value(line1, 1);
  gpiod_line_set_value(line2, 1);
  gpiod_line_set_value(line3, 1);
  sleep(3);
  gpiod_line_set_value(line1, 0);
  gpiod_line_set_value(line2, 0);
  gpiod_line_set_value(line3, 0);
  sleep(3);

  for (val=0; val<100; val++) {
    putchar('.');  fflush(stdout);
    gpiod_line_set_value(line1, (val & 0x01) != 0);
    gpiod_line_set_value(line2, (val & 0x02) != 0);
    gpiod_line_set_value(line3, (val & 0x04) != 0);
    sleep(1);
  }
  printf("done\n");

release_line:
  gpiod_line_release(line3);
close_chip:
  gpiod_chip_close(chip);
end:
  return 0;
}
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