the Raspberry Pi 4 has six SPI controllers, six I2C controllers, and six UARTs – all on its 40-pin header. You can’t make use of all of these at once, but with up to four different connections ...

Since the Raspberry Pi I/O pins operate at 3.3V this could connect to the B side, give you the ability to interface with i2c parts rated for lower or higher voltages. This is especially handy for ...