Flash ESP32-C3 BLE tester

Browser-based firmware installer for the dino tester peripheral used by the Web Bluetooth MTU samplers.

Web flasher

ESP32-C3 All BLE Tester built 2026-06-24

Connect the ESP32-C3 over USB, hold BOOT if your board needs manual download mode, then click Install.

Requires Chrome or Edge on desktop with Web Serial, served over HTTPS or localhost.

What this flashes

The firmware advertises as dino tester and exposes the sampler service:

Service:        0000ffe0-0000-1000-8000-00805f9b34fb
Characteristic: 0000ffe1-0000-1000-8000-00805f9b34fb
Device name:    dino tester

generic write echo for writes.html
mtu command returning peripheral-side peerMTU for mtu.html
lets go / get <seq> progressive JPEG streaming for dino.html

Build details

Compiled from ESP32C3_All_BLE_Tester using Arduino CLI, Espressif Arduino core esp32:esp32@3.3.10, and NimBLE-Arduino@2.5.0.

FQBN: esp32:esp32:esp32c3:CDCOnBoot=cdc,FlashSize=4M,CPUFreq=160,UploadSpeed=921600
Flash mode: dio
Flash freq: 80m
Flash size: 4MB

Download merged 4MB image View manifest SHA256SUMS

merged sha256
0b5a7080dfb6566e4093d3c1bd00f277f98eeb230ce8f86c23a35f7ceb59fbb0

Manual fallback

If Web Serial keeps failing at open(), flash the same binaries with esptool.py:

python3 -m pip install --user esptool
python3 -m esptool --chip esp32c3 --port /dev/ttyACM0 --baud 460800 write_flash \
  0x0 firmware/esp32c3-all-ble-tester-bootloader.bin \
  0x8000 firmware/esp32c3-all-ble-tester-partitions.bin \
  0xe000 firmware/esp32c3-all-ble-tester-boot-app0.bin \
  0x10000 firmware/esp32c3-all-ble-tester-app.bin

Use the port shown by ls /dev/ttyACM* /dev/ttyUSB*. Hold BOOT and tap RESET before running the command if the board does not enter download mode automatically.

Troubleshooting

"Failed to open serial port"

Seeing USB JTAG/serial debug unit is expected for ESP32-C3. If it pairs but then fails to open, the operating system is refusing Chrome's serial open.

Close Arduino IDE, VS Code, serial monitors, other flasher tabs, and any terminal using the same /dev/ttyACM* or /dev/ttyUSB* port.
Unplug and reconnect the board, then try again.
On Linux, check the port with ls -l /dev/ttyACM* /dev/ttyUSB*. For a quick one-time test: sudo chmod a+rw /dev/ttyACM0. Permanent fix: sudo usermod -a -G dialout $USER, then log out and back in.
If ModemManager grabs the port, stop it temporarily: sudo systemctl stop ModemManager.
If the board is running user firmware instead of the ROM bootloader, hold BOOT, tap RESET, click Install, then release BOOT after the connection starts.

Other issues

If no serial port appears, install the board's USB serial driver or try another USB cable.
After flashing, reset the board and open one of the samplers. The BLE device should show up as dino tester.

Back to sampler index Open MTU conformance test Open write-size probe Open streamer