由于在 LuckFox Pico 和 LuckFox Pico Plus 引脚复用，会有引脚功能冲突，所以默认不能全部开启 PWM功能。

】使用 GPIO sysfs 接口控制 PWM:

1] 查看默认开启的 PWM 接口：

# ls -l /sys/class/pwm

lrwxrwxrwx    1 root     root             0 pwmchip10 -> ../../devices/platform/ff490020.pwm/pwm/pwmchip10

lrwxrwxrwx    1 root     root             0 pwmchip1 -> ../../devices/platform/ff350010.pwm/pwm/pwmchip1

lrwxrwxrwx    1 root     root             0 pwmchip11 -> ../../devices/platform/ff490030.pwm/pwm/pwmchip11

lrwxrwxrwx    1 root     root             0 pwmchip0 -> ../../devices/platform/ff350000.pwm/pwm/pwmchip0

2] 测试 PWM。将PWM1_M0(GPIO0_A4_d)导出到用户空间:

echo 0 > /sys/class/pwm/pwmchip1/export

3] 设置 PWM 周期 单位为ns，比如 1KHz 频率的周期就是 1000000ns:

echo 1000000 > /sys/class/pwm/pwmchip1/pwm0/period

4] 设置占空比:
 #表示将占空比设置为 10%（100,000 纳秒为一个周期，持续时间为 10,000 纳秒）

echo 100000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle  

echo 200000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 300000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 400000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 500000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 600000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 700000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 800000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

echo 900000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

 #表示将占空比设置为 100%（1000000 纳秒为一个周期，持续时间为 1000000 纳秒）

echo 1000000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

#将占空比设为0，相当于停止占空比输出

echo 0 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

5] 设置正常 PWM 极性:

#设置正常pwm极性

echo "normal" > /sys/class/pwm/pwmchip1/pwm0/polarity

#设置翻转pwm极性:

echo "inversed" > /sys/class/pwm/pwmchip1/pwm0/polarity

6] 使能 PWM :

echo 1 > /sys/class/pwm/pwmchip1/pwm0/enable

7] 关闭 PWM :

echo 0 > /sys/class/pwm/pwmchip1/pwm0/enable

8] 取消将 PWM 导出到用户空间:

echo 0 > /sys/class/pwm/pwmchip1/unexport

9] 操作流程截图：