【完美体育·（中国）手机网页版MYD-Y6ULX-V2开发板】LED流水灯

由评测者“华仔stm32”提供。

对GPIO操作是最基本的功能之一。
【材料准备】
1、LED灯3个
2、杜绑线4条
3、面包板一块
【软件准备】
1、查看\01_Documents\User_Manual\Chinese\硬件手册 下面的MYD-Y6ULX-V2 硬件用户手册-V1.0.pdf。找到第23页4.7. GPIO/I2C/SPI/UART 接口。由于没有给出专门的GPIO接品，这里利用UART3接口来做GPIO输出。

2、查看IMX6ULL数据手册（工业级）找到对UART3的端口定义：

这里我们采用GPIO1_24 到26作为输出端口
J14的5、6、8分析接到面包板LED的正极，3脚接到面包板的地

3、编写led.c代码如下：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

int main(void)
{
    FILE *fp=NULL;
    int i=0;
    fp = fopen("/sys/class/gpio/export", "w");
    if (fp == NULL)
    {
        perror("fopen");
        return -1;
    }
    fprintf(fp,"%d",24);
    fclose(fp);
    fp = fopen("/sys/class/gpio/export", "w");
    if (fp == NULL)
    {
        perror("fopen");
        return -1;
    }
    fprintf(fp,"%d",25);
    fclose(fp);
    fp = fopen("/sys/class/gpio/export", "w");
    if (fp == NULL)
    {
        perror("fopen");
        return -1;
    }
    fprintf(fp,"%d",26);
    fclose(fp);
    
    fp = fopen("/sys/class/gpio/gpio24/direction","w");
    fprintf(fp,"out");
    fclose(fp);
    fp = fopen("/sys/class/gpio/gpio25/direction","w");
    fprintf(fp,"out");
    fclose(fp);
    fp = fopen("/sys/class/gpio/gpio26/direction","w");
    fprintf(fp,"out");
    fclose(fp);

    for(i=0; i<100;i++) {
        fp = fopen("/sys/class/gpio/gpio24/value", "w");
        fprintf(fp,"%d",1);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio25/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio26/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        sleep(1);

        fp = fopen("/sys/class/gpio/gpio24/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio25/value", "w");
        fprintf(fp,"%d",1);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio26/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        sleep(1);

        fp = fopen("/sys/class/gpio/gpio24/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio25/value", "w");
        fprintf(fp,"%d",0);
        fclose(fp);
        fp = fopen("/sys/class/gpio/gpio26/value", "w");
        fprintf(fp,"%d",1);
        fclose(fp);
        sleep(1);
    }
    fp = fopen("/sys/class/gpio/unexport","w");
    fprintf(fp,"%d",24);
    fclose(fp);
    fp = fopen("/sys/class/gpio/unexport","w");
    fprintf(fp,"%d",25);
    fclose(fp);
    fp = fopen("/sys/class/gpio/unexport","w");
    fprintf(fp,"%d",26);
    fclose(fp);

    return 0;
}

编译好后上传开发板，运行程序，就可以看到三个LED交替闪烁了。