i have the Stap C3 and i like to use the Pin G20 as Output to drive a small LED. The LED get 3.3V and the Output should switch to low to activate the LED. i also have a series resistor (Same circuit is working fine in G21 and G7). My test program is verry simple:

void setup() {
// put your setup code here, to run once:
pinMode(7, OUTPUT);
pinMode(20, OUTPUT);
pinMode(21, OUTPUT);
digitalWrite(7, 0);
digitalWrite(20, 0);
digitalWrite(21, 0);
}

void loop() {
// put your main code here, to run repeatedly:

}

only the LED on G7 and G21 is on. I think it have someting to do with the UART, becaus G20 is also RX. I´m sure the circuit is fine because the LED is flashing during the update process.

Does anyone know how i switch G20 to Output mode?

Gest regards,
Berni4