Configure the Serial UART

By default the Raspberry Pi has it’s external serial UART configured to monitor debug information via a terminal, this configuration can and should be changed to provide access to the “serial port” if required (for RFM2Pi for example).

To do this 2 files need to be edited (unless previously done).

 sudo nano /etc/inittab 

Locate this line in the file (it’s usually the last line)

# T0:23:respawn:/sbin/getty-LttyAMA0115200vt100

By default the hashtag (#) will not be present, this line should be commented out by adding the hashtag at the begining of the line if absent, the line needs to be as shown, with the hashtag. exit using ctrl-x saving any edits with y -> enter.

sudo nano /boot/cmdline.txt

This file contains one line, check to see if it contains this block of text,

console=ttyAMA0,115200kgdboc=ttyAMA0,115200

It should be removed leaving the remaining text as one line, exit using ctrl-x saving any edits with y -> enter.

Note - the changes will take effect at the next restart