[RPi] Hardware PWM

joan 超認真的, 不管是 forum 或是 stackexchange 都去回覆

簡單小結:
1. 建議使用 GPIO 12/13/18/19
http://raspberrypi.stackexchange.com/questions/53854/driving-pwm-output-frequency

2. 使用 pigpiod 可達到 8µs
http://raspberrypi.stackexchange.com/questions/54450/raspberry-pi-3-pwm

3. pigpiod 的用法
http://abyz.co.uk/rpi/pigpio/pigs.html#HP
http://abyz.co.uk/rpi/pigpio/python.html#hardware_clock
http://abyz.co.uk/rpi/pigpio/python.html

參考 overlay 的說明
http://www.jumpnowtek.com/rpi/Using-the-Raspberry-Pi-Hardware-PWM-timers.html
https://github.com/raspberrypi/linux/blob/rpi-4.4.y/arch/arm/boot/dts/overlays/README