Any wrong press on 2, 3 or 4 pin will not burn the tool board 1 pin is not allowed to receive any non-5V signal of the program board 2 pin is not allowed to receive any power supply of the program board
Line sequence illustration (small board) 1. 5V suggest cutting off it if it is not needed 2. GND 3. RX/SCL RX/SCL for program board reception 4. TX/SDA TX/SDA for program board reception