None of this works yet. This page is a WIP.

• MMDVM Repeater board
• Raspberry Pi

# curl https://mmdvm-tnc.s3.eu-west-2.amazonaws.com/flash-mmdvm-tnc.sh | sudo sh # NB this doesn't work yet

NB flashing seems to only work if you do it soon after plugging the board in to the header…

sudo raspi-config → interfaces → disable serial shell, leave serial port enabled

One-off:

curl -OL https://www.bi7jta.org/files/MMDVM_Firmware/repeater_HAT/stm32flashV5
chmod +x stm32flashV5
sudo sh -c "echo \"dtoverlay=disable-bt\" >> /boot/config.txt"
sudo systemctl disable hciuart

Every time:

wget -q https://mmdvm-tnc.s3.eu-west-2.amazonaws.com/mmdvm-f4-simplex.hex
while ! sudo ./stm32flashV5 -v -w mmdvm-f4-simplex.hex -R -i 20,-21,21:-20,-21,21 /dev/ttyAMA0; do echo again; done

Install board on Pi header

Burn Raspberry Pi OS Lite 32 bit to a micro SD, boot it

raspi-config → interfaces → disable serial shell, leave serial port enabled

sudo apt install -y git build-essential gcc-arm-none-eabi
git clone https://github.com/g4klx/MMDVM-TNC.git
cd MMDVM-TNC
git submodule init
git submodule update

Make Config.h look like this:

#define CONFIG_H
#define EXTERNAL_OSC 12000000
#define STM32F4_NUCLEO_MORPHO_HEADER
#define SERIAL_SPEED    115200

// Select the initial packet mode
// 1 = 1200 bps AFSK AX.25
// 2 = 9600 bps C4FSK IL2P
#define INITIAL_MODE    2

// TX Delay in milliseconds
#define TX_DELAY        300

// P-Persistence in x/255
#define P_PERSISTENCE   63

// Slot Time in milliseconds
#define SLOT_TIME       100

// Set Duplex, 1 for full duplex, 0 for simplex
#define DUPLEX          0

// Select use of serial debugging
#define SERIAL_DEBUGGING

// Baud rate for serial debugging.
#define DEBUGGING_SPEED 38400

// Set the receive level (out of 255)
#define RX_LEVEL        128

// Set the mode 1 transmit level (out of 255)
#define MODE1_TX_LEVEL  128

// Set the mode 2 transmit level (out of 255)
#define MODE2_TX_LEVEL  128

// Use pins to output the current mode via LEDs
#define MODE_LEDS

then run:

make dvm

Firmware is now built. Prep the Pi for flashing:

sudo sh -c "echo \"dtoverlay=disable-bt\" >> /boot/config.txt"
sudo systemctl disable hciuart

Flash it:

curl -OL https://www.bi7jta.org/files/MMDVM_Firmware/repeater_HAT/stm32flashV5
chmod +x stm32flashV5
sudo ./stm32flashV5 -v -w bin/mmdvm_f4.hex -R -i 20,-21,21:-20,-21,21 /dev/ttyAMA0

NB this seems to only work if you do it soon after plugging the board in to the header…

Mode 1 (1200 bit/sec AFSK AX.25) is D-Star LED

Mode 2 (9600 bit/sec C4FSK IL2P) is DMR LED

Nino has some nice TNC test tools.

cd ~
sudo apt install git python3 python3-pip -yq
sudo pip3 install pyserial
git clone https://github.com/ninocarrillo/tnc-tools.git
cd tnc-tools

Send one frame:

sudo python3 kiss-ax25-ui.py /dev/ttyAMA0 115200 m0lte-1

This will send frames repeatedly:

sudo python3 kiss-ax25-ui-batch.py /dev/ttyAMA0 115200 A0AAA B0BBB 100 "Hello world" 100 1

sudo required unless your user is in the dialout group.

Available via the TX and GND pins at the opposite end of the board to the DB9 socket.

On a typical USB serial breakout cable, connect TX to the white pin, and connect GND to the black pin. Open up PuTTY or similar and watch the COM port at 38400 baud.

Limited output such as “IL2PTX: type 1 header”.

• https://www.bi7jta.org/wiki/index.php?title=Main_Page#Compile_firmware