For the schematics see: WBUS_DIP68_schematics.pdf
For powering options please see the guidelines for the PYBD itself.
Note that the A3V3 pin is an output reference voltage only.
There are four tile headers on the top of the WBUS-DIP68. They are all connected together to the X pins of the PYBD, and the corresponding I2C and SPI buses are:
i2c = machine.I2C('X') spi = machine.SPI('X')