PMC modular bus
The PMC modular bus allows connection of PMC IO modules for additional functionality. The pinout is given below:
All signals are 3.3V logic level, INPUT bus can be from 7-55V.
Board internal connections
| PMC BUS SPI | CM SPI1 or STM SPI1 using A6,7 B3 |
| PMC BUS SPI Chip Selects (CS) | CM GP[24-27] or STM C[10-13] |
| PMC BUS I2C | CM I2C1 or STM I2C1 using B6,7 |
| PMC BUS IO CHIP | I2C line I2C1 on either CM or STM |
Note that the SPI and SPI Chip Selects are switched together, that is when SPI is selected to STM channel the data and CS pins will be on STM.
The IO Chip used to provide the G[1-8] digital signals on the PMC bus can be switched between any I2C1 source, regardless of what the PMC BUS I2C source is set to.
SPI control
SPI control signals (CS, CLK, MISO, MOSI) allow high-speed communication with PMC modules at up to 24Mbps.
I^2C control
GPIO expander
An I2C GPIO expander allows control of module-specific functions. The interface supports 2Mbps speed.