ThirdReality BL706 USB Dongle — Firmware Flashing Reference

Based on the ThirdReality Zigbee 3.0 USB Dongle repo (cloned at /opt/david/src/ThirdReality-Zigbee-3.0-USB-dongle/).

Hardware

Chip: Bouffalo Lab BL706 (NOT BL702 — different firmware!)
USB bridge: CH340 (1a86:7523, appears as /dev/ttyUSB0)
Protocol: BLZ (not ZiGate — firmware v1.00+)
Config: adapter: blz, baudrate: 2000000 in zigbee2mqtt configuration.yaml

CRITICAL: BL702 vs BL706 firmware

The ThirdReality dongle uses a BL706 chip. The DevCube flashing tool takes --chipname=bl702 (flash layout), but the firmware binary itself must be built for BL706, not BL702.

Firmware files named R3_bl702_dongle.bin (v1.00.07, v1.00.12) are for BL702 chips and will NOT boot on BL706. Always use firmware files named R3_706_dongle*.bin.

Working firmware: BLZ v1.00.01 (confirmed on BL706)

Saved in this repo at:

infra/zigbee2mqtt/R3_706_dongle_v1.00.01.bin
infra/zigbee2mqtt/partition_cfg_2M.toml

Entering Bootloader Mode

Hold the boot button (pinhole on the dongle) while plugging into USB. Release after ~1 second. No LED when in bootloader mode.

Flashing

BFLASH="/opt/david/src/ThirdReality-Zigbee-3.0-USB-dongle/Flashing-Tool
  /BouffaloLabDevCube-v1.9.0/bflb_iot_tool-ubuntu"
FIRMWARE="./infra/zigbee2mqtt/R3_706_dongle_v1.00.01.bin"
PARTITION="./infra/zigbee2mqtt/partition_cfg_2M.toml"

$BFLASH \
  --chipname=bl702 \
  --interface=uart \
  --port=/dev/ttyUSB0 \
  --baudrate=2000000 \
  --xtal=32M \
  --firmware=$FIRMWARE \
  --pt=$PARTITION

Critical flags

Flag	Value	Why
`--chipname`	`bl702`	Flash layout (not chip model — BL706 uses BL702 layout)
`--interface`	`uart`	CH340 provides serial passthrough
`--baudrate`	`2000000`	Must match the dongle's bootloader rate
`--xtal`	`32M`	Crystal frequency for bootheader generation
`--pt`	`partition_cfg_2M.toml`	Must use 2M — firmware overflows 1M

After Flashing

Tool prints [All Success] with SHA verification
Fully unplug the dongle (wait 5s for power drain)
Replug without holding any button
LED should light up immediately — chip is running the new firmware

Firmware Compatibility

Version	File name	BL706 compatible?
BLZ v1.00.01	`R3_706_dongle_v1.00.01.bin`	YES (confirmed working)
BLZ v1.00.07	`R3_bl702_dongle.bin` (misnamed)	NO — built for BL702
BLZ v1.00.12	`R3_bl702_dongle.bin` (misnamed)	NO — built for BL702
Legacy ZiGate v0.00.21	`R3_706_dongle.bin`	Untested (no BLZ support)

The v1.00.01 firmware file is in the ThirdReality repo at Image/Coordinator/blz/v1.00.01/R3_706_dongle_v1.00.01/.

Recurring Issue

After power loss, the BL706 firmware can corrupt itself (reports deviceId: 0xBEEF, addEndpoint fails with frameId:21). The chip responds to UART resets but refuses all application-layer commands. The fix is always to reflash with BL706-compatible firmware — there's no software recovery.

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