Flashing BL602 Microcontroller Using OpenBK: Step-by-Step Guide

4711leow wrote:

@ElektrodaBot
how to flash bl602 with openbk
AI: What hardware or connection method are you using to connect the BL602 to your computer (e.g., USB-to-serial adapter, specific dev board)?
usb to se...

Initial assessment of available information
- You’re on Ubuntu and will use a USB‑to‑serial adapter. The BL602 can be flashed reliably over UART if you strap BOOT (GPIO8) correctly and use the right UART pins and baud rate.
- The correct boot strap for BL602 flashing mode is: GPIO8 pulled HIGH (to 3.3 V) during reset/power‑up. Several online guides mistakenly say “BOOT to GND” (that’s true for some Espressif parts, not for BL602). On BL602 the ROM bootloader listens on UART0 with RX on GPIO7 and TX on GPIO16. (lupyuen.github.io)
- The OpenBeken project publishes ready‑to‑flash BL602 images on every release. As of 2025‑10‑05 the latest is 1.18.188 with assets “OpenBL602_1.18.188.bin” (UART flash) and “OpenBL602_1.18.188_OTA.bin.xz.ota” (OTA). (github.com)
- For flashing tools on Linux, Bouffalo’s CLI “bflb‑mcu‑tool” is current and maintained on PyPI; “blflash” (Rust) also works if you prefer it. BLDevCube GUI is another option. (pypi.org)

Direct answer to the question
Below is a minimal, working procedure to flash OpenBeken (OpenBK) onto a BL602 over USB‑to‑serial on Ubuntu:

1) Wiring (3.3 V only, not 5 V)
- GND → GND
- 3V3 → VDD (stable 3.3 V supply)
- Adapter TX → BL602 RX (GPIO7)
- Adapter RX → BL602 TX (GPIO16)
- BOOT (GPIO8) → pull up to 3.3 V during power‑up/reset (prefer 10 kΩ). (elektroda.com)

2) Put BL602 in flashing mode
- With power off, strap GPIO8 to 3.3 V (keep it high), then power up or reset. (lupyuen.github.io)

3) Install flashing tool
- sudo apt update && sudo apt install python3-pip
- python3 -m pip install --user bflb-mcu-tool (pypi.org)

4) Download OpenBeken for BL602
- Get the latest “OpenBL602_…​.bin” from the project’s Releases (UART Flash asset). (github.com)

5) Flash
- Typical fast attempt:
bflb-mcu-tool --chipname bl602 --port /dev/ttyUSB0 --baudrate 2000000 --firmware OpenBL602_x.y.z.bin
- If you see “Not ack OK/timeout”, retry at a lower baudrate, e.g. --baudrate 115200 or 200000. (pine64.github.io)

6) First boot
- Remove the BOOT strap (GPIO8 no longer forced high) and power‑cycle. The device should start OpenBeken and create an AP like OpenBL602_XXXX; connect and browse to 192.168.4.1 to configure Wi‑Fi. (coreforge.com)

If you prefer, you can use BLDevCube GUI (Linux build) with Interface=UART and 2 Mbps as the recommended rate; many adapters work more reliably at 115200–200000 baud. (pine64.github.io)

Detailed problem analysis
- Boot strap and UART pins
- The ROM loader on BL602 uses UART0 at GPIO7 (RX) and GPIO16 (TX). That’s why adapters wired to “typical” pins like GPIO14/15 won’t talk to the boot ROM during flashing. Ensure the crossover: adapter TX → GPIO7, adapter RX → GPIO16. (lupyuen.github.io)
- Entering the loader requires BOOT (GPIO8) HIGH at reset/power‑up; several vendor boards expose this as “IO8 H/L” jumper. Keep it high, then reset. (lupyuen.github.io)

- Tools
- bflb‑mcu‑tool (PyPI) mirrors DevCube’s MCU flashing flow on the command line and is actively maintained (v1.10.x in 2025). Start at 2 Mbps if your adapter is known‑good; otherwise fall back. (pypi.org)
- BLDevCube (GUI) is Bouffalo’s official tool; Pine64 docs show the UART workflow. It defaults to 2 Mbps and can be slow to start; if you get UART errors, reduce to 115200–200000. (pine64.github.io)
- blflash (Rust) is widely used by developers; it flashes a prepared image over UART and supports setting separate initial and main baud rates. (github.com)

- Image selection and addressing
- Use the OpenBeken “BL602 UART Flash” .bin from Releases. It’s prepared for the standard UART flashing flow; you don’t need to manually compose Boot2/partition/DTS. (github.com)
- If you use BLDevCube’s advanced pages, ensure the partition config matches your flash size (most consumer BL602 devices are 2 MB; using an incorrect table can prevent boot). If you’re unsure, back up first. (elektroda.com)

- Baud rate reality check
- Docs recommend 2 Mbps, but in practice cheap CH340/CP2102 adapters and long leads can drop packets. If you get “Not ack OK” or retries, try 115200–200000 baud; it’s slower but reliable. (pine64.github.io)

- Power
- Provide a stable 3.3 V supply. Some adapters can’t source enough current for Wi‑Fi bring‑up; use a proper 3.3 V LDO if you see brownouts (boot loops when AP starts). (elektroda.com)

Current information and trends
- Latest OpenBeken release (as of 2025‑10‑05): 1.18.188 with BL602 assets “OpenBL602_1.18.188.bin” (UART) and “…_OTA.bin.xz.ota” (OTA). (github.com)
- bflb‑mcu‑tool on PyPI shows active updates in 2025 (1.10.x). (pypi.org)

Supporting explanations and details
- Why BOOT=HIGH?
- The BL602 ROM checks GPIO8 at reset to select the ISP/loader. HIGH selects UART flashing, LOW continues normal boot. Vendor EVBs expose an IO8 “H/L” jumper for this reason. (lupyuen.github.io)
- Why GPIO7/16?
- The ROM’s default device tree/config maps UART0 RX/TX to GPIO7/GPIO16 at high baud; that’s what the loader expects before your firmware remaps anything. (lupyuen.github.io)

Practical guidelines (Ubuntu walkthrough)
1) Permissions
- Add yourself to the serial group and re-login:
sudo usermod -a -G dialout $USER
- Identify the adapter:
dmesg | grep -i tty
ls -l /dev/ttyUSB*

2) Install tool and get firmware
- python3 -m pip install --user bflb-mcu-tool
- Download OpenBL602_x.y.z.bin from the Releases page (BL602 “UART Flash” asset). (pypi.org)

3) Wire and enter flashing mode
- GND, 3V3, TX↔RX (TX→GPIO7, RX→GPIO16), BOOT (GPIO8) → 3.3 V.
- Power up or press reset with BOOT held high. (elektroda.com)

4) Flash
- Fast try:
bflb-mcu-tool --chipname bl602 --port /dev/ttyUSB0 --baudrate 2000000 --firmware OpenBL602_x.y.z.bin
- If handshake fails:
bflb-mcu-tool --chipname bl602 --port /dev/ttyUSB0 --baudrate 115200 --firmware OpenBL602_x.y.z.bin
(Optionally add --erase to wipe flash before programming.) (pypi.org)

5) First boot
- Remove BOOT strap, power‑cycle.
- Connect to AP “OpenBL602_…​” and browse to 192.168.4.1 to provision Wi‑Fi. (coreforge.com)

Optional alternatives:
- BLDevCube (GUI): Select BL602/604, Interface=UART, Port=/dev/ttyUSB0, Baud=2 000 000 (or 115200 if needed), load the BL602 UART Flash .bin in the firmware field, then program. (pine64.github.io)
- blflash:
./blflash flash OpenBL602_x.y.z.bin --port /dev/ttyUSB0
(Use --initial-baud-rate/--baud-rate if you need to slow down.) (github.com)

Troubleshooting
- Tool can’t open /dev/ttyUSB0: ensure you re‑logged after adding dialout or run with sudo once.
- “Not ack OK”, “timeout”, or repeated retries: lower baud, shorten wires, and use a better 3.3 V supply. (elektroda.com)
- No AP after flashing: confirm BOOT strap is removed; power‑cycle; if still no AP, re‑flash at lower baud, and verify your partition table matches flash size if you went through DevCube advanced pages. (elektroda.com)
- Backup/restore: before changes, you can read the entire flash with BLDevCube via UART (use ~200 kbaud if 2 Mbaud is unstable; for 2 MB devices read length 0x1FFFFF). (elektroda.com)

Ethical and safety aspects
- Disconnect mains completely when working on in‑circuit devices (bulbs, sockets). Never power the device from mains and the UART rig at the same time.

Possible disclaimers or additional notes
- Some BL602 boards (PineCone, DT‑BL10) expose boot/reset controls; follow the board‑specific sequence if available (e.g., set IO8 jumper “H”, press RESET). (lupyuen.github.io)

Suggestions for further research
- If your device is a MagicHome/CozyLife BL602 and you’d rather avoid soldering, there’s a documented OTA method using the OTA asset (…_OTA.bin.xz.ota). This uses the vendor’s update channel by serving the file locally. (elektroda.com)

Brief summary
- Wire GND/3V3 and cross TX/RX to GPIO7/16; pull BOOT (GPIO8) HIGH and reset to enter ROM loader; flash the latest OpenBL602 UART .bin with bflb‑mcu‑tool (or BLDevCube/blflash); remove BOOT and reboot; join the OpenBL602 AP to configure. (lupyuen.github.io)

Questions for the user
- Which exact BL602 device/board is this (module marking or product model)? I can provide a ready OpenBeken template (GPIO roles) for your hardware once I know the model.