2.2 40-pin GPIO to Raspberry Pi and jumper settings (PT-1201 only)

This connector provides the connection to the Raspberry Pi over the standard 40-pin GPIO connector.

This connector is implemented as stack-through, i.e. up to two IOL HATs can be connected on top of each other. If the pins are not occupied by the connected IOL HAT, additional expansion boards can be connected via the stack-through connector.

Stacking of two IOL HAT

The following pins are always in use when one or more IOL Hat modules are installed:

UsagePin
SPI: MISO (Master-In-Slave-Out)21 (SPI_MISO)
SPI: MOSI (Master-Out-Slave-In)19 (SPI_MOSI)
SPI: CLK (Clock)29 (SPI_CLK)
3V31,17
GND6,9,14,20,25,30,34,39

The SDCI ports 1+2 or 3+4 are selected via jumper JP1. The following positions select the corresponding SDCI port:

Use SDCI Port 1+2Use SDCI Port 3+4

Jumper positions other than those shown are not valid.

The following pins are used depending on the port selection:

UsageSDCI Port 1+2 Pin #SDCI Port 3+4 Pin #
SPI: CE (Chip Enable)24 (SPI_CE0)Pin 26 (SPI_CE1)
Interrupt18 (GPIO24)Pin 22 (GPIO25)

For the SPI interface, the Raspberry Pi acts as “master”, the IOL HAT as “slave”. The SPI mode is Mode 0 (CPOL=0; CPHA=0). All pins in the GPIO connector are connected through without modification.