Hi, if you don't have an Ethernet or GSM module connected to your INDIO, you can use the pins on the 14-pin IDC expansion port, they give you direct access to the MCU, Arduino-style. E.g. D4 and D6 are available (avoid D0,D1,D2,D3), see pinout see https://github.com/Industruino/documentation/blob/master/indio.md#idc-expansion-port-pinout
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