STMicroelectronics® Nucleo-WL55JC
The ST Nucleo-WL55JC (board reference MB1389) is STMicroelectronics' official evaluation board for the STM32WL. NUCLEO-WL55JC1 is built for the high frequency band (approximately 865–928 MHz) and NUCLEO-WL55JC2 for the low band (approximately 433–510 MHz). The two share a board design but wire out different RF paths and matching networks, so they are not interchangeable. It carries an onboard ST-LINK, so no external programmer is needed.
Specifications
- MCU
- STM32WL55JC (Arm Cortex-M4 application core, 256 kB flash, 64 kB RAM)
- LoRa Transceiver
- STM32WL integrated sub-GHz radio (Semtech SX126x-based), 32 MHz TCXO
- Frequency options
NUCLEO-WL55JC1: high band (~865–928 MHz)NUCLEO-WL55JC2: low band (~433–510 MHz)
- Antenna
- Single band-specific SMA connector
- Connectors
- USB Micro-B (ST-LINK)
- Arduino UNO V3 headers
- ST morpho headers
- Debug
- Onboard STLINK-V3E: SWD debug, Virtual COM Port, and drag-and-drop mass-storage programming
- Controls
- 3 user LEDs (green/blue/red)
- 3 user buttons (B1/B2/B3) and a reset button
- BOOT0 jumper (JP3)
Meshtastic pin mapping
Taken from the Meshtastic nucleo_wl55jc firmware variant. The Arduino UNO V3 headers (CN5 / CN8 / CN9) bring out a subset of the MCU pins; the ST morpho headers (CN7 / CN10) bring out every MCU pin.
| Function | Pin(s) | Arduino | Morpho | Meshtastic role |
|---|---|---|---|---|
| Console | ST-LINK Virtual COM Port (PA2 / PA3) | - | - | Default Serial (debug output and CLI) |
| GPS UART | PB6 (TX), PB7 (RX) — D1 / D0 | ✅ | ✅ | Serial2 (GPS_SERIAL_PORT=Serial2) |
| I2C | PA11 (SDA), PA12 (SCL) — D14 / D15 | ✅ | ✅ | Sensors |
| SPI | PA7 (MOSI), PA6 (MISO), PA5 (SCK) — D11 / D12 / D13 | ✅ | ✅ | Spare SPI bus |
| Green LED | PB9 | - | ✅ | LED_POWER |
| Red LED | PB11 | - | ✅ | LoRa activity |
| Blue LED | PB15 | - | ✅ | Notification |
| Button B1 | PA0 (WKUP-capable) | - | ✅ | Main button |
| Button B2 | PA1 | - | ✅ | Alternate button |
| Button B3 | PC6 | - | ✅ | Cancel button |
| VBAT sense | AVBAT (internal ADC channel) | - | - | BATTERY_PIN, but VBAT is tied to 3V3 by default (SB21) so this reads the rail, not a battery |
Flashing
Everything runs through the onboard ST-LINK, including drag-and-drop of firmware-nucleo_wl55jc-X.X.X.xxxxxxx.bin onto the board's USB mass-storage drive.
Resources
- Firmware file:
firmware-nucleo_wl55jc-X.X.X.xxxxxxx.bin - NUCLEO-WL55JC product page
- UM2592: STM32WL Nucleo-64 board (MB1389) user manual