RK linux下如何测试pwm功能

1、使能pwm模块的某个通道：

echo 1 > /sys/class/pwm/pwmchip0/export

2、配置pwm的周期， (单位为纳秒,1000000000 ns = 1s)

echo 1000000000 > /sys/class/pwm/pwmchip0/pwm1/period

3、配置pwm的占空比， (单位为纳秒,1000000000 ns = 1s， 占空比为50%, 0.5 s)

echo 500000000 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle

4、占空比以及极性 (pwm信号中以低电平为开启状态，还是以高电平为开启状态，这里设置为普通极性，也就是高电平为开启状态)

echo 'normal' > /sys/class/pwm/pwmchip0/pwm1/polarity

5、使能pwm信号的输出

echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable

6、关掉 pwm信号的输出

echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable