See the top level README for information on where to find the schematic and programmers reference manual for the ARM processor on the raspberry pi. Also find information on how to load and run these programs. Based on uart01, this one enables the uart rxd1 receiver (gpio15). It starts by printing 12345678 then whatever you type on the terminal is echoed back. See the top level README file for information on how to connect the raspi uart to your host computer. Using a dumb terminal (minicom) 115200 board No parity 8 bits 1 stop bit, no flow control (might have to exit minicom and start again for the flow control setting to take). What you type on the dumb terminal comes back.