我正在使用 Adafruit Ft232H 分线器将 GPIO 端口添加到我的 Linux 电脑。虽然我在使用和 bitbang 模式闪烁 LED 方面取得了一些成功libftdi，但我没有同样的运气，libgpiod因为gpiod_line_request_output它失败了。
我系统的一些gpio信息：
sudo gpiodetect
gpiochip0 [ftdi-cbus] (4 lines)
sudo gpioinfo
gpiochip0 - 4 lines:
line 0: unnamed unused input active-high
line 1: unnamed unused input active-high
line 2: unnamed unused input active-high
line 3: unnamed unused input active-high
这是试图访问第 0 行的 C 程序。
#include <stdio.h>
#include <stdlib.h>
#include <gpiod.h>
#define LINE_NUM 0
void gpio_fatal(struct gpiod_chip* chip, const char msg[20]);
int main(int argc, char** argv)
{
struct gpiod_chip* chip;
struct gpiod_line* line;
const char path[] = "/dev/gpiochip0";
chip = gpiod_chip_open(path);
if(!chip)
{
fprintf(stderr, "Error opening path\n");
return EXIT_FAILURE;
}
line = gpiod_chip_get_line(chip, LINE_NUM);
if(!line)
{
fprintf(stderr, "error getting this line\n");
return EXIT_FAILURE;
}
int ret = gpiod_line_request_output(line,
"ftdi-cbus",
1);
if(ret != 0)
gpio_fatal(chip, "Request output failed");
for(;;)
{
gpiod_line_set_value(line, 1);
printf("On\n");
sleep(1);
gpiod_line_set_value(line, 0);
printf("Off\n");
sleep(1);
}
gpiod_line_release(line);
gpiod_chip_close(chip);
return EXIT_SUCCESS;
}
void gpio_fatal(struct gpiod_chip* chip, const char* msg)
{
fprintf(stderr, "%s\n", msg);
gpiod_chip_close(chip);
exit(EXIT_FAILURE);
}
运行可执行文件sudo给我：
sudo g_gpiod/build/g_gpiod
Password:
Request output failed
gpiod.h失败功能的状态如下：
/**
* @brief Reserve a single line, set the direction to output.
* @param line GPIO line object.
* @param consumer Name of the consumer.
* @param default_val Initial line value.
* @return 0 if the line was properly reserved, -1 on failure.
*/
int gpiod_line_request_output(struct gpiod_line *line,
const char *consumer, int default_val) GPIOD_API;
参数似乎是正确的，为什么会失败？libftdi使用或CircuitPython可以访问端口并正常工作的其他示例。