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Flashing MeshCore Firmware

Flashing MeshCore Firmware

MeshCore firmware can be installed via the web flasher (easiest), with command-line flashing tools (esptool for ESP32, UF2 drag-and-drop for nRF52), or OTA (over-the-air) for updates on already-running devices. All methods are covered below.

Method 1: Web Flasher (Recommended)

The web flasher at flasher.meshcore.co.uk (the canonical URL; the .io alias may resolve but is not official - URL accurate as of 2026-06-08) requires a Chromium-based browser (Chrome or Edge). Firefox does not support the WebSerial API and will not work.

  1. Open flasher.meshcore.co.uk in Chrome or Edge.
  2. Connect your device via USB. Use a data-capable USB cable. Charge-only cables (common with power banks) will not expose the serial port. If the device does not appear, try a different cable first.
  3. Hold the BOOT button while plugging in (ESP32 devices) or double-tap the reset button (nRF52 devices) to enter bootloader mode.
  4. Select your device type from the dropdown.
  5. Select the firmware variant:
    • Companion - pairs with a phone app over BLE or USB
    • Repeater - autonomous relay node, no interaction needed
    • Room Server - store-and-forward message hub
  6. Click Flash. The process takes 1 - 2 minutes. Do not disconnect during flashing.
  7. After flashing completes, configure the device via the MeshCore app or CLI.

Method 2: Command-Line Flashing

Note: meshcore-cli does not flash firmware - it connects to an already-running node to configure and interact with it (see Post-Flash Configuration below). Command-line flashing uses the standard chip-flashing tools instead, which is useful for bulk deployments or when the web flasher is unavailable.

ESP32 boards (V3, T-Beam, Station G2, etc.) - esptool: Install Python 3 first, then install esptool. On many systems use pip3 if pip is not found; on recent Linux/macOS a bare system pip install is blocked (PEP 668), so use a virtual environment or pipx:

pip3 install esptool   # or: pipx install esptool

Put the board in bootloader mode (hold BOOT while connecting USB), then write the MeshCore merged firmware .bin. Replace the port and filename to match your system:

esptool.py --port COM3 write_flash 0x0 meshcore-firmware.bin       # Windows
esptool.py --port /dev/ttyUSB0 write_flash 0x0 meshcore-firmware.bin  # Linux/macOS

nRF52 boards (RAK4631, Heltec T114, T-Echo, etc.) - UF2 drag-and-drop: Double-tap the reset button to enter the UF2 bootloader. The board appears as a USB mass-storage drive; copy the MeshCore .uf2 file onto that drive. The board flashes and reboots automatically. No command-line tool is required.

Method 3: OTA Update (ESP32 devices only)

For devices already running MeshCore firmware, OTA updates avoid needing a USB connection.

  1. In the MeshCore app, open the Command Line for your device.
  2. Type: start ota
  3. The device will create a Wi-Fi hotspot named MeshCore OTA.
  4. Connect your phone or computer to the MeshCore OTA Wi-Fi network.
  5. Open a browser and navigate to http://192.168.4.1/update
  6. Upload the new firmware file (.bin). Wait for the device to reboot.

Method 4: OTA Update (nRF52 devices)

nRF52-based devices use the Nordic DFU protocol for OTA updates.

  1. In the MeshCore app, type start ota in the Command Line.
  2. Use the nRF Device Firmware Update app (available for Android/iOS).
  3. Select the firmware .zip DFU package and transfer. The standard DFU flow handles transfer automatically; leave the app's transfer/packet-receipt settings at their defaults unless the MeshCore release notes for your board specify otherwise.

Bootloader Entry by Device

DeviceMethod
Most ESP32 devices (V3, V4, T-Beam)Hold BOOT button while connecting USB
nRF52 (T-Echo, RAK WisBlock, Wio series)Double-tap reset button quickly
LilyGo T-Deck variantsDepress trackball while connecting USB
Heltec V3Uses a CP2102 USB-serial bridge - install the Silicon Labs CP210x driver first
Heltec V4Native USB CDC (the CP2102 was removed on V4) - no external USB-serial driver needed

Post-Flash Configuration (meshcore-cli)

After flashing, the device needs basic configuration before it will function on the network. You can configure it from the MeshCore app, or from a terminal with meshcore-cli, which connects to a running node (it does not flash firmware). Install it with pip3 install meshcore-cli (use a venv or pipx on PEP 668 systems), then connect using one of:

meshcore-cli -s COM3            # serial (Windows); use -s /dev/ttyUSB0 on Linux/macOS
meshcore-cli -a <BLE address>   # BLE by address (or -S to scan and pick from a selector)
meshcore-cli -t 192.168.1.100 -p 5000   # TCP/IP (default port 5000)

Then set the basics:

  • Set device name (used to identify you in the mesh)
  • Set region/frequency. For North America select the US region: this constrains the radio to the 902-928 MHz band (commonly shorthanded "915 MHz") and is the primary compliance control - the US region preset enforces the band edges and caps TX power to the FCC Part 15 limit. Do not select a non-US region or disable the cap.
  • Set TX power. For unlicensed US operation, conducted output must not exceed 30 dBm (1 W) and must be reduced further for antennas above 6 dBi (so total EIRP stays within the 36 dBm / 47 CFR 15.247 ceiling). The US region preset normally caps power correctly, but verify on high-power hardware (e.g. Station G2 or 2 W modules), which can default or be set above the legal limit. Reduce power for indoor testing.
  • For Repeater variant: set the repeater name and ensure auto-start is enabled
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