GPIO Input/Ouput Summary Description
0 & 1 Output UART TX & RX Some diagnostic information is written to the UART including error messages if scoppy enounters an unrecoverable error
2 & 3 Input - pulled down CH1 Voltage Range Currently selected voltage range for channel 1
4 & 5 Input - pulled down CH2 Voltage Range Currently selected voltage range for channel 2
6 to 13 Input Logic Analyzer inputs Connect up to 8 digital sources (0V to 3.3V)
22 Output Test signal PWM 1kHz 50% duty cycle - can be connected directly to either of the ADC inputs
26 Input CH1 ADC input Connect the +ve output of your analog frontend (or signal source) here. Connect the ground of the analog frontend (or signal source) to GND.
27 Input CH2 ADC input Connect the +ve output of your analog frontend (or signal source) here. Connect the ground of the analog frontend (or signal source) to GND.

Please note that the test signal and voltage range GPIO assignments changed in version 4 of the firmware (previously they were GPIO 16 and 22 for the test signal, 3 and 4 for the channel 1 voltage range and 6 & 7 for the channel 2 voltage range).