Build Your Own Gateway Navigation:
Build Your Own Gateway – Welcome
Build Your Own Gateway – Part 1: What You’ll Need
Build Your Own Gateway – Part 2: Installing SVXLink
Build Your Own Gateway – Part 3: Configuring SVXLink
Build Your Own Gateway – Part 4: Connecting To The Radio
Build Your Own Gateway – Part 5: Programming the Radio
Build Your Own Gateway – Part 6: Connecting to the Reflector
Build Your Own Gateway – Part 7: Adjusting Audio Levels

Connecting the MTM800e to the Pi

To connect the MTM800e to the Pi, you’re going to need to follow the following wiring guide to connect up the 3.3v FTDI cable for PEI data, and your chosen Sound Card (Signalink, or R1 2020)

Radio Pins (MTM800e)

The below diagram is of the rear of the MTM800e, with the rear of the radio facing you. Note the location of pin 1.

Rear of the MTM800e

PEI Data Connectivity – 3.3V FTDI Cable

To send/receive PEI data between the Raspberry Pi and the radio, you’ll need to connect your FTDI cable to the rear of the MTM800e.

Radio PINFTDI CableUseNotes
8BlackGround (Digital)Ground
17BrownCTSClear to Send – not always required.

Sound Card Connectivity

You’ll need to connect your chosen soundcard to to the rear of the MTM800e too for send/receive audio and PTT to work.

Follow the pin guides below, depending upon which soundcard you’ve chosen.

Signalink Pins

If you're using a Signalink as your soundcard, use the below pin guide.

Note that the below guide assumes that you've directly mapped the PTT, Mic, Speaker and Group pins from the A side to the B side inside the Signalink (this is not done by default).

Radio PIN Signalink CAT5e Use Notes
1 n/a Speaker Used to connect external speaker to radio
16 n/a Speaker Used to connect external speaker to radio
3 Green/White PTT Push to Talk from the Signalink
7 Green Ground (Analogue) Analogue Ground
11 White/Orange RX Audio Received Audio
2 Orange TX Audio TX Line In Audio

R1 2020 Pins

If you're using the R1 2020 soundcard (blue box), use the below diagram and pin guide to connect the soundcard to the MTM800e.

Note the pins are numbered right to left on the 26 pin connector that comes with the R1 2020 soundcard, so long as you're holding the connector with the pin holes facing you, and the DIN connector is facing upwards and away from you.

R1 2020 26 pin connector.

Radio Pin R1 2020 Socket Use Notes
11 14 RX Audio Receive audio. Red in my image above
7 12 Ground (Audio) Black in my image above.
3 17 PTT White in my image above
5* 11 TX Audio Transmit audio. Yellow in my image above.
Note - the cable colours used in the above example are just the coloured GPIO jumper cables I happened to use. Yours may be different.

* - I'd recommend Pin 5 for transmit audio, but you can also use Pin 2 (you can change this in the codeplug of the radio in CPS).

R1 2020 Switches

Ensure the switches on the R1 2020 are set as following:

Top switch: Moto
Bottom Switch: ASL On

R1 2020 USB Connection to your Pi

To connect the R1 2020 to your Raspberry Pi, connect the usb A/B cable between the USB Audio port and a spare USB port on your Pi. There's no need to connect the other two USB ports (USB detection and USB serial port) on the R1 2020.

Build Your Own Gateway – Part 5: Programming the Radio >