#!/bin/bash

# 控制LED的gpio管脚
gpio_pin=26
# 闪烁间隔时间
intervals=1

# 处理程序运行参数
# 支持设置 "normal", "fast", "slowly" 三种闪烁速度
if [ $# == 1 ];then
	case $1 in
		"normal")
			intervals=1
			;;
		"fast")
			intervals=0.3
			;;
		"slowly")
			intervals=2
			;;
		"*")
			intervals=1
			;;
	esac
fi

# 运行前先释放一下
echo ${gpio_pin} > /sys/class/gpio/unexport 2>/dev/null

# 申请 LED 灯的控制管脚，设置功能为GPIO功能
echo ${gpio_pin} > /sys/class/gpio/export
if [ $? -ne 0 ]; then
	echo "Failed to request LED control pin"
	exit 1
fi
echo "Request LED control pin successfully"


# 设置控制管脚为输出模式
echo out > /sys/class/gpio/gpio${gpio_pin}/direction
if [ $? -ne 0 ]; then
	echo "Failed to set LED control pin to output mode"
	exit 1
fi
echo "Set LED control pin to output mode successfully"

echo "Let the LED into cycle on and off mode"

# 开始控制LED循环亮灭，1秒钟变化
while [ true ];
do
	echo 1 >  /sys/class/gpio/gpio${gpio_pin}/value
	sleep ${intervals}
	echo 0 >  /sys/class/gpio/gpio${gpio_pin}/value
	sleep ${intervals}
done
