# Second serial port on EXP 2 connector

<abstract>
This article explains how to enable and use a secondary TTL serial port on EXP2 connector
</abstract>

To enable the serial Port 0 of Raspberry Pi module instead of GPIO or SPI port add this line in /boot/config.txt

	dtoverlay=uart0,txd0_pin=36,rxd0_pin=37,pin_func=6

Reboot the CM3-Panel and check that the port exists by typing:

	ls -al /dev/tty*

	...
	crw-rw---- 1 root dialout 204, 64 May 18 15:36 /dev/ttyAMA0
	...


The port is available as __/dev/ttyAMA0__ device

The line will be 

| EXP2 Pin # | Signal |
|------------|--------|
| GPIO 36    | TXD0   |
| GPIO 37    | RXD0   |