Meshtastic-mini — Wio-E5-LE Mini (STM32WLE5JC)

Meshtastic-compatible LoRa mesh firmware for Seeed Studio Wio-E5-LE Mini. LoRa mesh only, config via Serial, no BLE/GPS/display.

Platform

• MCU: STM32WLE5JC (Cortex-M4 + integrated sub-GHz radio)
• Radio: integrated SX1262-compatible, controlled via STM32WL HAL (SUBGHZSPI)
• Interfaces: UART (Serial) for config and application; no BLE/GPS/display
• RF switch: PA4 (RF_CTRL1), PA5 (RF_CTRL2). Default: RFO_HP (High Power PA)

Build

Prerequisites

• arm-none-eabi-gcc
• CMake 3.16+
• Git submodules initialized

Quick start

git submodule update --init --recursive
./build.sh build    # → build/meshtastic_mini.elf
./build.sh flash    # Flash via OpenOCD / st-flash

Manual build

mkdir build && cd build
cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-none-eabi.cmake
cmake --build .

CMake options

Option	Default	Description
WIO_E5_USE_LP	OFF	Use RFO_LP PA instead of RFO_HP
WIO_E5_NO_TCXO	OFF	Disable TCXO (crystal-only boards)
USE_STM32WL_RADIO	ON	SubGHz driver
USE_NANOPB	ON	nanopb runtime

Radio link test

Two boards connected via USB — automatic bidirectional ping-pong:

pip install pyserial
python3 scripts/check_radio_link.py

Expected output:

[ttyUSB0] -> [ttyUSB1]: 'ping'
  OK: [ttyUSB1] received 'ping', [ttyUSB0] received 'pong'
[ttyUSB1] -> [ttyUSB0]: 'ping'
  OK: [ttyUSB0] received 'ping', [ttyUSB1] received 'pong'
PASS: radio link OK (both directions)

Options: --timeout 15, explicit ports: python3 scripts/check_radio_link.py /dev/ttyUSB0 /dev/ttyUSB1

Serial interface

USART1: PB6 (TX), PB7 (RX), 115200 8N1.

On boot: Meshtastic_mini started, mesh init done, loop.

Any text entered in the terminal is sent as LoRa payload. For example, typing hello + Enter sends the bytes "hello" over LoRa to all nodes. This is not a command — it is data transmitted by radio.

Received packets appear as: RX: <text> RSSI: -XX dBm SNR: X dB. The receiver automatically replies with "pong".

Commands (reserved words):

Command	Description
N1 … N9	Set node_id (e.g. N1 on first board, N2 on second)
info	Show frequency (MHz), SF, NodeId, last RSSI
help	List commands

SDR frequency

Default region EU868: 869.525 MHz, BW 250 kHz, SF11.

Protocol

LoRa header (16 bytes)

Offset	Size	Field	Description
0x00	4	To	Destination NodeID (0xFFFFFFFF = broadcast)
0x04	4	From	Sender NodeID
0x08	4	Packet ID	Unique packet ID
0x0C	1	Flags	HopLimit, WantAck, ViaMQTT, HopStart
0x0D	1	Channel	Channel index/hash
0x0E	1	Next hop	For relaying
0x0F	1	Relay	Relaying node

Flood routing

On receive: if hop_limit > 0 and packet not seen (by Packet ID + From), decrement hop_limit and rebroadcast.

AES-128 encryption

STM32WLE5 hardware AES. Channel PSK 16 bytes → AES-128. Header is not encrypted; only payload.

Connecting to other Meshtastic nodes

To communicate with phones (Meshtastic app), ESP32 nodes, or any Meshtastic device: use the same region, Long Fast (or same preset), and the same channel key. See docs/CONNECTING_TO_MESHTASTIC.md for requirements, default LongFast PSK, step-by-step setup, and limitations.

Project structure

Meshtastic_mini/
├── CMakeLists.txt
├── cmake/                  # Toolchain, HAL/CMSIS/nanopb cmake
├── scripts/                # check_radio_link.py, dual_serial_monitor.py
├── firmware/
│   ├── Core/               # main_loop, serial_io, led, system_clock
│   ├── Radio/              # radio_stm32wl, lora_meshtastic, radio_phy, rf_ctrl
│   ├── Mesh/               # mesh_packet, flood_router
│   ├── Serial/             # serial_framing
│   ├── Crypto/             # aes_meshtastic
│   └── Config/             # config_store
└── third_party/            # STM32CubeWL, nanopb, meshtastic_protobufs

Links

• Meshtastic LoRa Configuration
• Meshtastic Protobufs
• STM32WLE5 Reference Manual
• Wio-E5-LE Mini
• Seeed LoRaWan-E5-Node

Removing Readout Protection

To allow flashing: set RDP level to AA, nBOOT0 = 0 via STM32CubeProgrammer.