Friday, September 12, 2014

Using Raspberry Pi Serial Port

             By default the Raspberry Pi’s serial port is configured to be used for console input/output, it means you can't use the Serial Port in your programs and  needs to be disabled.To enable the serial port for your own use you need to disable login on the port. There are two files that need to be edited

The first and main one is     

              
 /etc/inittab


This file has the command to enable the login prompt and this needs to be disabled. Edit the file and move to the end of the file. You will see a line similar to

                      
      
T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100


Disable it by adding a # character to the beginning. Save the file.


          When the Raspberry Pi boots up, all the bootup information is sent to the serial port. Disabling this bootup information is optional and you may want to leave this enabled as it is sometimes useful to see what is happening at bootup. If you have a device connected (i.e. Arduino) at bootup, it will receive this information over the serial port, so it is up to you to decide whether this is a problem or not.
You can disable it by editing the file

                             
/boot/cmdline.txt


The contents of the file look like this

dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
Remove all references to ttyAMA0 (which is the name of the serial port). The file will now look like this


dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait


In order you enable the changes you have made, you will need to reboot the Raspberry Pi

                         
sudo shutdown -r now