swaits
46822c182c
First RP2040 board and third MCU family (after ESP32-S3 and nRF52840). Hardware: RP2040 + SX1262 radio, 850-930 MHz HF, PE4259 antenna switch, LED on GPIO25, no OLED, USB-C via FPC ribbon cable to adapter board. New files: - src/hal/rp2040.rs: MCU primitives (SPI bus, USB driver, flash unique ID MAC) - src/board/waveshare_rp2040_lora.rs: board implementation - ld/rp2040-memory.x: linker memory layout Also fixes cortex-m-rt/set-vtor (moved from global dep to per-board feature, since Cortex-M0+ has no VTOR register) and makes build.rs memory.x selection target-aware.
DongLoRa Firmware
Embedded Rust firmware for DongLoRa boards. Exposes the LoRa radio over USB CDC-ACM using a COBS-framed binary protocol.
Building
just setup # one-time toolchain install
just build heltec_v4 # build for a specific board
just flash heltec_v4 # build + flash
just check-all # compile-check all boards
just clippy heltec_v4 # lint
just test # host-side protocol unit tests
All commands are run from the firmware/ directory.
Supported Boards
| Board | Feature | MCU | Radio | USB | Target |
|---|---|---|---|---|---|
| Heltec V3 | heltec_v3 |
ESP32-S3 | SX1262 | Native CDC-ACM | xtensa-esp32s3-none-elf |
| Heltec V3 (UART) | heltec_v3_uart |
ESP32-S3 | SX1262 | CP2102 bridge | xtensa-esp32s3-none-elf |
| Heltec V4 | heltec_v4 |
ESP32-S3 | SX1262 | Native CDC-ACM | xtensa-esp32s3-none-elf |
| RAK WisBlock 4631 | rak_wisblock_4631 |
nRF52840 | SX1262 | Native CDC-ACM | thumbv7em-none-eabihf |
| Waveshare RP2040-LoRa | waveshare_rp2040_lora |
RP2040 | SX1262 | Native CDC-ACM | thumbv6m-none-eabi |
| Wio Tracker L1 | wio_tracker_l1 |
nRF52840 | SX1262 | Native CDC-ACM | thumbv7em-none-eabihf |
Heltec V3 USB Note
The default heltec_v3 build uses native USB CDC-ACM, which requires a
hardware modification to your board. Stock Heltec V3 boards route USB through a
CP2102 bridge chip to UART — the ESP32-S3's native USB pins (GPIO19/GPIO20) are
routed to header pins but not connected to the USB connector.
To enable native USB on a Heltec V3:
- Solder 0-ohm (or 22-ohm) resistors at pads R29 (D+) and R3 (D-)
- Disconnect the CP2102 from the USB connector's D+/D- lines (cut traces or remove the CP2102 bridge resistors)
After this mod, the board appears as /dev/ttyACM0 with the DongLoRa VID:PID
(1209:5741), just like the V4 and nRF boards.
If you have a stock (unmodified) V3, use heltec_v3_uart instead:
just build heltec_v3_uart
just flash heltec_v3_uart
This builds firmware that communicates via the CP2102 bridge (appears as
/dev/ttyUSB0).
Adding a Board
See src/board/PORTING.md.
Protocol
See PROTOCOL.md for the complete wire format specification.