Thanks talv2010 and sobieh

BTT Relay Firmware mod for Klipper

Upload

1. Install python 3.x

2. PowerShell command

pip install stcgal

3. Connect your board to any USB to Serial adapter

4. Put on Reset jumper

5. PowerShell command

upload.bat COM#

where # is your COM port number

6. Erase Reset jumper

Klipper printer.cfg

Add this lines to your printer.cfg config file:

  [output_pin RELAY_ON_OFF]
  pin: YOUR_MOTHERBOARD_PIN
  value: 1

Now after Klipper starts it should set HIGH level on pin

Emergency Stop set LOW level, so printer will lost power

You can use G-code to remove power:

  SET_PIN PIN=RELAY_ON_OFF VALUE=0 ; immediately shut down the printer

Modify by your own

Microcontroller: STC15W204S

Keil C51 uVision

STC ISP programming software (v6.91)

For uVision compiler setup use that video