@berni You can use any digital bidirectional (i.e. non analogue input only) pin which is not allocated to another functionality. This means you should avoid: P13-P18 since they are input-only pins, P12 which is used for antenna selection, P5-P7 which are used for LoRa radio, and P0-P1 used for UART.

@soibac35 if pinNumber is already a string, you do not need str(pinNumber).

@shedaim I'd agree with @robert-hh. Such "test points" are often incorporated into a PCB for automatic testing during production. Most boards pass through an automatic testing stage during manufacture and at that time it can be "pressed down" onto a jig that makes contact with these test points and allows for full testing and quite often the loading of any boot code required. Here are some similar looking test points inside, of all things, and electric toothbrush. Note that they have helpfully labelled a lot of the test points on the silkscreen (Hint hint, Pycom) [image: toothbrush_programming_header_-_1.jpg]

See also my post here https://forum.pycom.io/topic/4130/pinout-pysense-etc

@mci For coding the content of the pins.csv file is effective, because that file is used for mapping the Pxx and Gxx numbers to the GPIO port numbers,

For completness one might also mention that there are another pins which should be used with care: MTDI / P9 is the ESP strapping pin to select the voltage of the internal LDO. MTDO / P4 is the ESP strapping pin for debug logging during boot GPIO2 / P8 (together with PIO0) is the ESP strapping pin to select boot mode GPIO5 / Sigfox CLK (together with MTDO) is the ESP strapping pin to select SDIO Timing

@panos29 P20 is an ADC1 pin, are you sure you can't use it? As for the ADC2 that is not currently supported in the Python side because it it's a bit of an oddball: due to hardware/firmware limitations you can't use WiFi and ADC2 at the same time. For now to use it you'd have to program in C and have WiFi off.

@jmarcelino D'oh! You'r right. It's a ESP32. After 20 years with Atmels and PICs, my mind falls back into this world... Cheers, Thomas