LoRA APRS Tracker Automotive 13.8v

Assembled - RF.Guru LoRA APRS Tracker Automotive 433Mhz 400mW Power

Installation

Quick Install (pre-built firmware)

1. Download LoRa433APRSTracker.uf2 from the latest release
2. Connect the device via USB-C (do not connect the 13.8v Powerpole)
3. Enter UF2 bootloader mode:
   • Hold the reset button on the PCB while plugging in USB-C, or
   • Run ./reset.sh /dev/tty.usbmodem* (installs pyserial automatically)
4. A drive named RPI-RP2 will appear - copy the .uf2 file to it
5. The device reboots automatically and a new drive named APRSTRKR appears
6. Edit config.txt on the drive (see Configuration below)
7. Eject the drive - the device reboots with your settings

Configuration

After flashing, the device presents as a USB drive with a config.txt file. Edit it to configure:

• callsign - Your APRS callsign (e.g. ON9RFG-1)
• profile - SmartBeacon profile: car, bike, or hiker
• power - TX power 5-23 dBm
• triggerVoltageCall - Callsign to alert on low voltage
• loraFrequency - LoRa frequency in MHz (default 433.775)
• i2cEnabled - Enable I2C sensors (true/false)
• i2cDevice - Sensor type: BME680 or SHTC3

Eject the USB drive to apply changes (device reboots automatically).

Firmware Update

To update to a new firmware version, either:

• Repeat the Quick Install steps above with the new .uf2 file, or
• Edit config.txt on the USB drive, replace all content with just firmwareupdate, and eject - the device will reboot into UF2 bootloader mode ready for the new firmware

Factory Reset

Copy flash_nuke.uf2 to the RPI-RP2 drive to erase all flash, then reflash the firmware.

Building from Source

Requires PlatformIO.

pio run

The firmware will be at .pio/build/pico/firmware.uf2.

Serial Debugging/Console

Install tio: https://github.com/tio/tio

tio --auto-connect new

The console shows colored output with GPS status, LoRa TX frames, and voltage monitoring.

Warnings

The PA only runs on 13.8V via the PP45 connector. If you power the unit from USB, the power amplifier is not powered/active, so there will be no amplified output.