Raspberry pi expansion system page

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If you want to hook up your raspberry pi to interface with the rest of the world, this is the right place to look!

For some things like standard RS232 serial ports or webcams, you can get cheap USB devices. But to drive a small 16x2 character LCD, or to switch mains-power rpi_serial is for you.


The rpi_serial board is the simplest breakout board for the Raspberry pi.

It breaks out the following serial buses:

  • SPI0
  • SPI1
  • I2C
  • UART

As the rasberrypi runs at 3.3V IO signal levels, the board allows 5V peripherals to be connected. The board can be configured for 5V operation or for 3.3V operation but not both.

Rpi_ui: the raspbery pi user interface

This board is available in a version with 20x4 and a version with 16x2 display. As the rpi_serial it breaks out all the serial busses of the raspberry pi. It also has a display and 6 buttons integrated on the board. These are accessible through SPI0 or the I2C bus.

Expansion boards

The following expansion boards have been designed:

Planned are the optocoupler expansion board and the button expansion board. If you have suggestions for more, please let us know.

These expansion boards have two SPI connectors. The first SPI connector is for data transfer during normal operation. The other can be used to daisy-chain the SPI bus to other SPI expansion boards. Or it can be configured to be used as the programming port for the onboard AVR chip.

It should be possible to use one of the raspberry pi SPI buses for data-transfer, while you use the other one to program the AVR chip on the expansion board.