Uart connector pinout

The rpi_serial and ftdi_serial boards use a 4-pin connector.

The connector is laid out as follows:

pin	function	remark
1	GND	Power Ground
2	RXD	recieve Data (input)
3	TXD	transmit data (output)
4	VCC	Power 5V (or 3.3V).

To connect the RPI_SERIAL to an ftdi_serial board, you'll need a null modem (crossover) cable. You can consider leaving the power line unconnected. (on both boards you can power a small project from this pin. For example an AVR processor can easily communicate with the RPI over the serial connection and at the same time be powered from the power pin.)

Connecting the BitWizard boards to an Arduino

pin	function	arduino pin	Arduino Mega
1	GND	GND	GND
2	RXD	D1	TXD on the arduino
3	TXD	D0	RXD on the arduino
4	VCC	VCC	VCC

Note that there is also the FT232(*) USB-serial chip connected to these pins. To connect your arduino to the raspberry pi, we recommend you use USB.

On the other hand, the above setup will be useful if you then take the chip out of the arduino and build a project with the bare chip.

(*) It's an at90usb162 on newer arduinos IIRC.