Hi, The PF pin translate definition is "Output active high frequency square wave pulse, duty cycle 50%". So it is the pulse frequncy output signal for the power usage. You can use UART otuput to read data or use this PF pulse to read power data.

I'm using this board with esp32 and works great. But, I still have one question about PF pin. What's it does? I didn't find any code with this pin. Only find datasheet in Chinese and I can't understand the fuction of PF PIN. All projects use only tx pin for Uart communication. Could you help me with this question? What the PF PIN is use for? Thank you for attention.

Dependable. Works for years now.