Freematics Forum

I recently purchased a FreematicsOne/Trackie unit and I am having trouble figuring out how to use the external I/O pins. I would like to add some custom sensors to the unit. I read here that "Two I/O pins (PC0, PC1 or A0, A1 in Arduino context) are led out to one corner of PCB. They can be used for digital I/O and analog input."

Given that information, I tried running a very simple Arduino sketch that read pin A0 as an analog input. Printing the value to the Serial Monitor showed that it started at 200 something and dropped to about 40, regardless on what I connected to the two input pins (either short to ground or connect ot 5V).

Looking at the Molex jack, I can tell that the top-right is 5V and bottom-right is GND and I assume A0 would be one of the left two pins.

I'm probably completely missing something. Any help would be appreciated.

I figured out that the I/O pins are actually the solder points next to the LED. Can the RXD/TXD pins be used as regular digital inputs?

A0 and A1 there. They can be used as analog input, digital input/output and software serial.