本文來源電子發燒友社區，作者：劉建華， 帖子地址：https://bbs.elecfans.com/jishu_2308743_1_1.html

【目的】學習使用GPIO外設。
1、學習資源：EASY EAI靈眸科技 | 讓邊緣AI落地更簡單 (easy-eai.com)認直學習了gpio外設的使用。
2、在靈眸科技的示例文件夾下新建文件mypro1。在該文件夾下新建一個mypo1_gpio.c

3、代碼如下：

#include 
#include 
#include 

#ifndef	CONSUMER
#define	CONSUMER	"Consumer"
#endif

int main(int argc, char **argv)
{
	char *chipname = "gpiochip3";
	unsigned int line_num = 11;	// GPIO GPIO3_B3
	unsigned int val;
	struct gpiod_chip *chip;
	struct gpiod_line *line;
	int i, ret;

	chip = gpiod_chip_open_by_name(chipname);
	if (!chip) {
		perror("Open chip failedn");
		goto end;
	}

	line = gpiod_chip_get_line(chip, line_num);
	if (!line) {
		perror("Get line failedn");
		goto close_chip;
	}

	ret = gpiod_line_request_output(line, CONSUMER, 0, 0);
	if (ret < 0) {
		perror("Request line as output failedn");
		goto release_line;
	}

	/* Blink 20 times */
	val = 0;
	for (i = 20; i > 0; i--) {
		ret = gpiod_line_set_value(line, val);
		if (ret < 0) {
			perror("Set line output failedn");
			goto release_line;
		}
		printf("Output %u on line #%un", val, line_num);
		sleep(1);
		val = !val;
	}

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

3、在其的demo下面拷貝build.sh到文件夾下。再拷貝一個makefile.txt到此文件下，修改makefile.txt如下：

cmake_minimum_required(VERSION 2.8.4)

STRING(REGEX REPLACE ".*/(.*)" "1" CURRENT_FOLDER ${CMAKE_CURRENT_SOURCE_DIR} )
MESSAGE("current project: " ${CURRENT_FOLDER})

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_CROSSCOMPILING TRUE)

set(CMAKE_C_COMPILER "arm-linux-gnueabihf-gcc")
set(CMAKE_CXX_COMPILER "arm-linux-gnueabihf-g++")

# find host dir and set CMAKE_TOOLCHAIN_FILE before call project
execute_process(COMMAND which ${CMAKE_C_COMPILER} 
                OUTPUT_VARIABLE gcc_full_path)
get_filename_component(gcc_full_dir ${gcc_full_path} DIRECTORY)
set(HOST_DIR "${gcc_full_dir}/..")
set(CMAKE_TOOLCHAIN_FILE "${HOST_DIR}/share/buildroot/toolchainfile.cmake")

project(${CURRENT_FOLDER})
add_definitions(-Wall)

set(toolkit_root ${CMAKE_CURRENT_SOURCE_DIR}/../easyeai-api)

#--------------------------
# test-gpio
#--------------------------
add_executable(my_gpio mypro1_gpio.c)		#-o  這里指定要編譯的文件與輸出的文件名
target_link_libraries(my_gpio pthread gpiod)	#-l  這里指鏈接的文件名my_gpio

4、編譯，執行./build.sh，生成了my_gpio。

5、用file檢查一下my_gpio，是arm的程序。

6、用adb push到開發板：

developer@EASY-EAI-Develop:~/EASY-EAI-Toolkit-C-Demo/mypro1/build$ adb push my_gpio /userdata/Demo/my_gpio
my_gpio: 1 file pushed. 0.4 MB/s (12308 bytes in 0.026s)

7、用杜綁線將開發板P1的15腳與LED燈的正級相連，LED燈的負極接開發板的地。

8、adb登錄到開發板，進入userdata/Demo目錄，執行./my_gpio:

看到終端輸入，同時LED燈也一秒交替亮滅。

附上開發板體驗視頻（詳見作者原試用帖子）