***************************************************************** ************** enable the serial data port on the pi 2 ********** ***************************************************************** The following instructions work on the Raspberry Pi-2 ( NOT THE Pi 3 ) running the Debian 8 (Jessie) For instructions on the Raspberry Pi-3 running Stretch go to the bottom of this file in the file /boot/config.txt add these two lines core_freq=250 enable_uart=1 raspi-config select 9 advanced options Select A8 serial Would you like a login shell to be accessible over serial? no serial is now disabled = ok select "finish" would you like to reboot now = yes ---------------------------------------------------- set the baud rate of the port with this command stty -F /dev/ttyAMA0 9600 # Parameter contents Narrow,Xmit_Freq,Rcv_Freq,Rcv_CTCSS,squelch,Xmit_CTCSS,RF_power Programming command for a two meter transceiver board: echo "AT+DMOSETGROUP=1,147.9950,147.9950,12,3,0,0" > /dev/ttyAMA0 # 12 = PL 100 Hz Programming command for a 440 MHz transceiver board: echo "AT+DMOSETGROUP=1,440.0050,440.0050,12,3,0,0" > /dev/ttyAMA0 # 12 = PL 100 Hz ----------------------------------- ############################################################################################# ############################################################################################# ############################################################################################# SLIGHTLY DIFFERENT INSTRUCTIONS BELOW FOR THE PI-3 RUNNING DEBIAN 9 STRETCH ############################################################################################# ############################################################################################# ############################################################################################# in the file /boot/config.txt add these two lines core_freq=250 enable_uart=1 on the putty command line as user root run this command - raspi-config select - 5 interface options Select - p6 serial Would you like a login shell to be accessible over serial? = no Would you like the serial port to be enabled? = yes The serial login shell is disabled The serial interface is enabled select "ok" select "finish" would you like to reboot now = yes - - - - - - - YOU ARE ALL DONE - - - - - - - - - - - - - set the baud rate of the port with this command stty -F /dev/ttyS0 9600 To send text out pin 8 on the pi header use this command # Parameter contents Narrow,Xmit_Freq,Rcv_Freq,Rcv_CTCSS,squelch,Xmit_CTCSS,RF_power Programming command for a two meter transceiver board: echo "AT+DMOSETGROUP=1,147.9950,147.9950,12,3,0,0" > /dev/ttyS0 # 12 = PL 100 Hz Programming command for a 440 MHz transceiver board: echo "AT+DMOSETGROUP=1,440.0050,440.0050,12,3,0,0" > /dev/ttyS0 # 12 = PL 100 Hz ------------------------------------------------------------------------------------------------- The above info was "gleened" from these two weblinks umong others. https://www.raspberrypi.org/documentation/configuration/uart.md https://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/