The Pi-Lite has an on-board Arduino with pre-loaded software. By supplying power to the Pi-Lite board, you can use either the serial port (GPIO pin 10, UART-RXD and GPIO pin 8, UART-TXD), or the FTDI pins to send data and commands to drive the display. You need to be careful to ensure you use 3.3V or 5V serial signalling. Example: a wireless display unit

As an example, the picture below shows the Pi-Lite (with its default firmware) connected to an XRF, This scrolls in the text 5C and then halts scrolling due to the command initiator: $$$.

The Pi-Lite is connected up via the FTDI connector pins to an XRF Breakout Board (XBBO) with an XRF on board. This makes it easy to place the whole system on a breadboard. Here how they are connected together: