Pin mapping for SPI / I2C connection to Cinterion TC65T module

  • I need a serial connection between a LoPy4 and an (older) TC65T GSM module. The GSM module has a combined I2C/SPI interface sharing 2 pins. Yet i do not know if my software will use SPI oder I2C for interfacing. What pin mapping should i use on my LoPy4, so that i later can decide if i use SPI oder I2C and get not conflicts?

    The pin mapping of the TC65T modem is as follows, sharing pins 1+2 for I2C and SPI:

    (Pin) Signal name // Pin Description
    (13) SPICS Chip select // selects and activates the external device via a low signal.
    (14) SPIDI Data in // serial data input line (from external device to TC65 Terminal)
    (1) I2CDAT_SPIDO Data out // serial data output line (from TC65 Terminal to external device)
    (2) I2CCLK_SPICLK // Serial clock line

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