TCA9548 = 0x70 ; Selects which I/O slot the I2C should be connected to.
The MCU slot is made for any Colibri MCU variant.
It can be programmed from the pin header on the Colibri-3
Each expansion slot can be communicated to with I2C or SPI.
The I2C is connected via an I2C MUX on the board, to avoid address conflicts.
The SPI has a 3 Chip Select demux (PA0, PA1, PA2) signals per slot, only allowing selection of 1 CS at a time.
Each slot has +3.3V, +5V and +12V power, and the 3.3 and 5 Volt can be individually controlled on/off from the MCU. The external power supply is also available for the expansion boards to utilize.
Finally, each slot has 4 pins going to the 4-pole screw terminals on the Colibri-3.
The Colibri-3 can be powered by AC (5-36V) or DC (7-55V). But some expansion (Colibri Triac-1 for now) boards require AC power, and if powered with DC, those boards will not work.
The device consumes very little power, typically well below 1 Watt. Expansion boards may consume maximum 200mA on each power rail, and that may increase the power consumption substantially. The on-board power supply can supply 3A on 5V and 1A on 3.3V.