Firmware Flashing

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.io (the canonical flasher, run by the MeshCore core team and linked from the official docs - URL accurate as of 2026-06-13) requires a Chromium-based browser (Chrome or Edge). Firefox does not support the WebSerial API and will not work. Note: flasher.meshcore.co.uk is a separate, downstream flasher associated with the MeshOS variant - for standard MeshCore, use flasher.meshcore.io.
Open flasher.meshcore.io in Chrome or Edge.
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.
Hold the BOOT button while plugging in (ESP32 devices) or double-tap the reset button (nRF52 devices) to enter bootloader mode.
Select your device type from the dropdown.
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
 
Click Flash. The process takes 1 - 2 minutes. Do not disconnect during flashing.
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)
For devices already running MeshCore firmware, OTA updates avoid needing a USB connection. ESP32 boards update over a temporary Wi-Fi access point. See Flashing MeshCore Firmware OTA: The Definitive Guide in the MeshCore book for the full walkthrough.
In the MeshCore app, open the Command Line for your device.
Type: 
start ota
The device will create a Wi-Fi hotspot named MeshCore-OTA (it may appear as "MeshCore OTA").
Connect your phone or computer to that Wi-Fi network.
Open a browser and navigate to http://192.168.4.1/update
Upload the non-merged firmware file (.bin) - not the merged .bin, which is for first-time USB flashing. Wait for the device to reboot.
Method 4: OTA Update (nRF52 devices)
nRF52-based devices use the Nordic DFU protocol for OTA updates. Installing the OTAFIX bootloader (from flasher.meshcore.io) first makes BLE OTA far more reliable. See Flashing MeshCore Firmware OTA: The Definitive Guide for the full walkthrough.
Place the device in OTA DFU mode (with OTAFIX installed, hold the button while resetting; otherwise issue 
start ota in the MeshCore app Command Line).
Use the nRF Device Firmware Update app (available for Android/iOS; it appears as "DFU" in your app list).
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
Device
Method
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 variants
Depress trackball while connecting USB
Heltec V3
Uses a CP2102 USB-serial bridge - install the Silicon Labs CP210x driver first
Heltec V4
Native 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

Flashing Meshtastic Firmware
Flashing Meshtastic Firmware
Meshtastic firmware is flashed via the web flasher at flasher.meshtastic.org or via the Meshtastic Python CLI. The process is similar to MeshCore but has some differences in device selection and channels.
Web Flasher
Open flasher.meshtastic.org in Chrome or Edge. Firefox will not work (no WebSerial support).
Connect the device via a USB data cable. Enter bootloader mode:
 
 
ESP32: hold BOOT button while plugging in
 
nRF52: double-tap reset button
 
T-Deck: depress trackball while connecting
 
Select your device from the dropdown. If your device is not listed, check the Meshtastic hardware support page.
Choose firmware channel:
 
 
Stable - recommended for most users; well-tested
 
Alpha - latest features, may have bugs
 
Click Flash. The process takes 1 - 3 minutes depending on device.
Driver Requirements
Some devices require USB-serial drivers before the OS will recognise them. If unsure, check the silkscreen label on the USB-serial chip near the USB connector:
Chip
Driver
Common Devices
CP2102 / CP210x
Silicon Labs CP210x driver
Heltec V3, some T-Beam variants
CH340/CH341
CH340 driver (Windows/macOS)
Some LilyGo boards (and occasional clone units of other boards)
Native USB CDC
No driver needed
Heltec V4 (the CP2102 was removed on V4)
nRF52840 UF2 bootloader
No driver needed - appears as a USB mass-storage drive
T-Echo, RAK WisBlock, most nRF52
Note: the Heltec WiFi LoRa 32 V3 uses a CP2102 bridge (install the Silicon Labs CP210x driver); the V4 uses native USB CDC and needs no external driver. Occasional units or clones may ship with a CH340 - if the CP210x driver does not produce a COM port, check the chip silkscreen.
First-Time Configuration
After flashing Meshtastic, use the Meshtastic app (Android/iOS) or web client to configure:
Region: Set to US (902-928 MHz, commonly shorthanded "915 MHz") for North America. Beyond interoperability (a wrong region means you cannot communicate with local nodes), the region setting is the legal control: the US region enforces the FCC band edges (902-928 MHz) and caps TX power to the legal Part 15 maximum (30 dBm conducted, reduced for antennas above 6 dBi). Selecting a non-US region to gain power or change frequency can put you outside US law.
Role: CLIENT for normal/personal devices; ROUTER only for genuine fixed infrastructure (the Meshtastic project discourages casual use of ROUTER, as a misused router role can degrade the mesh). The older ROUTER_CLIENT role was retired in firmware 2.3.15 - use CLIENT (or CLIENT_MUTE) instead, including for mobile/vehicle nodes. See the Meshtastic role documentation for the current guidance.
Long name / short name: How you appear to other users on the mesh.
Channel: Must match other nodes you want to communicate with. Default channel works for public networks.
Re-Flashing Between Firmware Versions
You can move between Meshtastic stable and alpha, or between Meshtastic and MeshCore, at any time. Re-flashing normally does not physically damage the hardware, but a wrong or interrupted flash - especially using the wrong bootloader/.uf2 on an nRF52 board - can leave the device temporarily unbootable; see Flashing Troubleshooting for recovery. Configuration is reset when flashing a new firmware type, so note your settings before switching.

Flashing Troubleshooting
Flashing Troubleshooting
Most flashing failures fall into a small set of categories. Work through this table before assuming the device is damaged.
Troubleshooting Table
Symptom
Likely Cause
Fix
 
Device not detected by browser or OS
 
Charge-only USB cable; wrong USB port; missing drivers
 
Try a different cable (data-capable); try a different USB port; install CH340 or CP2102 drivers; try a different computer
 
Device detected but flash fails immediately
 
Not in bootloader mode
 
Hold BOOT while connecting (ESP32) or double-tap reset (nRF52); consult device-specific instructions
 
Device won't boot after flashing
 
Wrong firmware build selected
 
Verify you selected the correct device in the flasher; re-flash with correct build
 
Flashed wrong variant (e.g., Repeater instead of Companion)
 
User error
 
Re-flash with correct variant; no permanent damage
 
ESP32 completely unresponsive / "bricked"
 
Corrupted flash
 
Hold BOOT button → connect USB → run: 
esptool.py --port COM3 erase_flash (substitute your actual port, e.g. 
/dev/ttyUSB0 on Linux or 
/dev/cu.usbserial-* on macOS) → re-flash firmware. On newer installs the command may be 
esptool or 
python -m esptool; run 
pip install esptool first.
 
nRF52 unresponsive
 
Corrupted firmware
 
Double-tap reset button to enter DFU mode → reflash via DFU
 
Linux: "Permission denied" on /dev/ttyUSB0
 
User not in dialout group
 
sudo usermod -a -G dialout $USER then log out and back in
 
Linux: Web flasher cannot connect
 
udev rules / ACL issue
 
setfacl -m u:$USER:rw /dev/ttyUSB0
 
macOS: Device not appearing in /dev/
 
Missing USB-serial driver (depends on the board's USB chip)
 
Identify the chip first. CH340/CH9102 boards: install 
CH34xVCPDriver from wch.cn (or the Homebrew formula). CP210x boards (many Heltec/older devices): install the Silicon Labs CP210x VCP driver. Newer boards with native USB (nRF52 DFU, ESP32-S3 native CDC, e.g. Heltec V4) need no driver and enumerate as 
/dev/cu.usbmodem*. Recent macOS bundles some drivers, but a missing-device symptom usually means the matching VCP driver is not installed.
 
Flash completes but device shows wrong region or settings
 
Old config preserved in flash
 
Perform a factory reset via the app or by flashing with "erase before flash" option checked
esptool.py Emergency Erase
If an ESP32 device is completely unresponsive and normal bootloader entry fails:
pip install esptool
esptool.py --port COM3 erase_flash # Windows
esptool.py --port /dev/ttyUSB0 erase_flash # Linux
After erasing, the chip will be blank. Re-flash the firmware normally via the web flasher. (On newer esptool installs the command may be invoked as 
esptool or 
python -m esptool instead of 
esptool.py.)
Identifying Your Serial Port
Windows: Device Manager → Ports (COM & LPT) → look for CH340 or CP210x device. Note the COM number (e.g., COM5).
Linux: Run 
ls /dev/tty* before and after plugging in the device. The new entry is your device (typically /dev/ttyUSB0 or /dev/ttyACM0).
macOS: Run 
ls /dev/cu.*. Look for cu.usbserial-* or cu.wchusbserial*.