RPI SPI8

8-Channel SPI Bus Multiplexer for the Raspberry Pi

• 8 channels
• Supports SPI star topology
  • MISO from all slaves are wired together
• Connects to the SPI pins on the Raspberry Pi

SPI Star Topology

From Practical EE: SPI Bus page:

In Star topology all the signals are split and routed to each slave in parallel, except chip select. Multiple chip select are used to select individual slave devices. More devices support this mode than daisy-chain.

Connectors

40-Pin Raspberry Pi Connector

• • SPIMISO - GPIO Pin 21
  • SPIMOSI - GPIO Pin 19
  • SPISCK - GPIO Pin 23
  • SPICE0 - GPIO Pin 24
• Three GPIO pins select SPI channel
  • GPIO Pin 22 - A0
  • GPIO Pin 27 - A1
  • GPIO Pin 17 - A2

SPI Connectors

Four of 2x6 right angle headers

1. SPICE0[0-7]
2. SPIMOSI
3. SPIMISO
4. SPISCK
5. VCC (3.3V from Raspberry Pi)
6. GND

Programming

• Set channel number on GPIO Pin 22 (A0), GPIO Pin 27 (A1), GPIO Pin 17 (A2)
• Do SPI transfer
• SPI on the Raspberry Pi
• Python Spidev

Factory Test Procedure

Setup

• SPI0 is disabled by default.
  • To enable it, use raspi-config, or ensure the line dtparam=spi=on isn't commented out in /boot/config.txt.
  • By default it uses 2 chip select lines, but this can be reduced to 1 using dtoverlay=spi0-1cs.
  • dtoverlay=spi0-2cs also exists, and without any parameters it is equivalent to dtparam=spi=on.
• Use n SPI-POTX2 cards
• Requires n SPI cables

Assembly Sheet

RPI-SPI8 Assembly Sheet - Rev 1