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CK-BL602-4SW-WH Firmware Update Guide: OTA & Manual Methods

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User question

Ck-bl602-4sw-wh firmware update

Artificial Intelligence Response

Direct answer to the question

• The CK-BL602-4SW-WH smart-switch can be updated in two fundamentally different ways:
 1. Official OTA (over-the-air) update delivered through the manufacturer’s Tuya/Smart-Life or eWeLink cloud/app – current official release ≈ v1.3.0 (roll-out started Mar 2025, mainly for DST fix).
 2. Manual flashing of a complete image through the BL602 serial bootloader (Bouffalo Dev-Cube, BLFlashCommand) or via Wi-Fi using the open-source “OpenBeken” web flasher – this path allows stock firmware recovery, custom OpenBeken/Tasmota firmware, or laboratory debugging.

Key points
• Use OTA when you only need the vendor’s latest bug-fix/security release – it is safe, under warranty, and requires no tools.
• Use manual flashing only if you want full local control, MQTT/Home-Assistant integration, or the device is bricked. It requires 3.3 V UART access or a Wi-Fi bootstrap image and voids the warranty.

Detailed problem analysis

  1. Device architecture
     • BL602 SoC (RISC-V @ 192 MHz, Wi-Fi b/g/n 2.4 GHz + BLE 5.0)
     • 4 × relay outputs + 4 × tactile inputs (typ. GPIO 6/7/8/9 for relays on reference designs)
     • Internal 2 MB QSPI flash that stores bootloader + application

  2. Boot & update capabilities
     • Mask-ROM bootloader reached when BOOT = HIGH during reset (3.3 V logic) → provides 2 Mbaud UART flashing protocol.
     • Vendor firmware includes an OTA agent that talks to Tuya/eWeLink cloud and writes a signed update package to flash bank-B, swaps banks on next boot.
     • OpenBeken implements its own OTA (HTTP/HTTPS or web-upload) once the first custom image is installed.

  3. Official OTA procedure (Tuya/Smart-Life or eWeLink)
     a. Ensure switch is powered, online in the app, RSSI > -70 dBm.
     b. App → Device → Settings (⚙/✎) → Firmware Update → “Check for Update”.
     c. If “v1.3.0” (or newer) is offered, tap Update. Keep mains power on; the relay may cycle once.
     d. After ~3–5 min the app shows “Up-to-date”. Confirm new build number.

  4. Manual/Recovery flashing paths

 4.1 Serial (USB-UART, 3.3 V)
  • Bill-of-materials
   – FT232RL / CP2102 adapter (3.3 V)
   – Dupont leads or pogo-pins; optional 1 kΩ pull-up for BOOT
   – Bouffalo Dev Cube v1.8 + or Python BLFlashCommand
  • Pad mapping (typical CK-BL602 board – verify visually!)

  | Pad | Function | Adapter pin |
  |-----|----------|------------|
  | GND | Ground | GND |
  | 3V3 | 3.3 V | 3V3 supply |
  | TXD | SoC-TX | RX (PC) |
  | RXD | SoC-RX | TX (PC) |
  | BOOT| Pull HIGH to 3.3 V during reset | n/a |

  • Sequence
   1. Isolate from mains! Open housing, locate test pads.
   2. Wire adapter (cross TX/RX).
   3. Hold BOOT pad to 3.3 V, plug USB → SoC enters download mode.
   4. Dev Cube → Chip BL602 → 2 000 000 baud → “Erase + Program” → select firmware.bin.
   5. When done, release BOOT, reset.

 4.2 Wi-Fi web-flasher (OpenBeken bootstrap) — “ltchiptool”
  • If the unit still runs stock firmware and has never been opened, you may be able to load a minimal loader over Wi-Fi (exploits Tuya OTA fallback). The elektroda tutorial (Ref [4]) provides the signed OBK-mini image and a browser-based tool; no soldering needed.
  • After first flash, connect to AP OpenBeken_xxxxxx, set WLAN credentials, then visit http://<IP> → Tools → OTA to upload full image.

  1. Protecting the original image
     • Before experimenting, use Dev Cube “Read Flash” to dump 2 MB to backup_original.bin. Store safely; it can be re-written if you need to revert for RMA.

  2. GPIO template for OpenBeken (community-verified) 

    {"cfg_total":"65","btn1":"17","btn2":"13","btn3":"14","btn4":"18",
"relay1":"6","relay2":"7","relay3":"8","relay4":"9","led1":"11"}

    (Template may vary – confirm with multimeter or incremental test from OBK web UI)

Current information and trends

• Official firmware v1.3.x (March 2025) addresses automatic Daylight Saving Time switching and WPA3 compatibility (source: eWeLink blog, Ref [2]).
• OpenBeken has merged BL602 support with the same code-base used for BK7231T/N & XR809, enabling MQTT, Home Assistant auto-discovery, REST API, and scripting (Refs [3], [7]).
• Community tooling (ltchiptool) moved to a pure browser/WebSerial implementation, removing Python and driver dependencies, and supports incremental OTA diff-patching to reduce flash-wear.
• Increasing industry push toward Matter-over-Wi-Fi; BL602 is technically capable but needs firmware re-architecture – experimental Matter branch exists in OpenBeken forks.

Supporting explanations and details

• Why 2 Mbaud? The on-chip bootloader sets 2 000 000 bps 8-N-1 by default; using slower speeds increases flashing time but is tolerated.
• Power isolation: Although the UART adapter can power the logic, keep the mains line completely disconnected; the triac/relay board ties neutral and presents lethal voltage otherwise.
• Fail-safe mechanisms: Stock firmware has A/B bank and CRC validation; OpenBeken has dual-slot loader and soft-recovery via safe-mode AP if the application crashes within 3 s.

Ethical and legal aspects

• Warranty: Any non-official firmware or physical opening voids vendor warranty and possibly violates local consumer laws if not disclosed when requesting RMA.
• Regulatory compliance: Custom firmware must ensure continued compliance with FCC/CE radiated-emission limits; altering 2.4 GHz output power or channel plan may breach regulations.
• Security: Unsigned custom builds increase attack surface; always compile from source or verify SHA-256 signatures from trusted repositories.

Practical guidelines

Implementation checklist (manual flash):

  1. Tools ready, driver checks, multimeter for continuity.
  2. Photograph PCB before soldering.
  3. Backup original flash.
  4. Validate binary size ≤ 1290240 bytes (fits BL602 partition).
  5. After flashing custom firmware, immediately set a strong web UI password and, if using MQTT, configure TLS‐enabled broker.

Typical pitfalls & remedies
• “Sync fail” in Dev Cube → wrong baud or BOOT not high.
• Device reboots every 5 s after custom flash → wrong GPIO template; bootloop protection triggers. Hold Button 1 at power-up to enter OBK safe mode, then fix pins.
• OTA stuck at 10 % → weak Wi-Fi; bring AP closer, retry.

Possible disclaimers or additional notes

• Some early CK-BL602-4SW-WH batches shipped with only 1 MB flash – custom images larger than 512 kB will not fit; read flash size (blflashinfo) before proceeding.
• Tuya sometimes locks OTA with a product secret; if the OTA button disappears, wait for staged rollout or contact the reseller.
• No known way to downgrade stock firmware once Tuya increments the secure-boot revision. Always test new versions on one device before fleet deployment.

Suggestions for further research

• Monitor Bouffalo Lab’s SDK release notes for BL602 SDK v1.8+ (improved TLS 1.3 stack, Matter demo).
• Follow the OpenBeken GitHub discussions on unified “Matter-bridge” mode.
• Investigate zigbee-to-BL602 multi-protocol concurrency (recent academic papers show BLE+802.15.4 time-slicing).
• Consider reverse-engineering the Tuya OTA package signing to enable delta-patch analysis.

Brief summary

For most users the simplest, safest approach is the vendor’s OTA update through Tuya/Smart-Life or eWeLink, which as of March 2025 delivers firmware v1.3.0 with DST fixes.
Advanced users can unlock far greater flexibility by backing up the original image and flashing OpenBeken (or other R-C open firmware) via 3.3 V UART or, in many cases, entirely over Wi-Fi with the WebSerial flasher. Careful pin-mapping, reliable 3.3 V power, and strict ESD/mains isolation are essential to avoid a permanent brick. Always weigh the benefits of local control and privacy against the higher technical risk and regulatory responsibilities of running custom code.

User question

how to flash CK-BL602-4SW-WH over wifi?

Artificial Intelligence Response

Direct answer to the question

  • You can flash the CK-BL602-4SW-WH over Wi‑Fi (no opening, no soldering) by using the stock firmware’s OTA path. The reliable path on BL602 devices is: 1) put the device into AP/pairing mode, 2) host the correct OpenBeken “OTA” image on a simple local HTTP server, 3) send an AT command over UDP (port 48899) telling the device to fetch and install that image, 4) after reboot, connect to the OpenBeken AP at 192.168.4.1 and finish setup.
  • If your unit’s OEM firmware has the OTA/AT path disabled (common on newer batches), Wi‑Fi flashing will not work and you must use serial flashing instead.

Key points

  • Use the OpenBeken build made for BL602 in OTA format (filename ends with .ota; do not use BK7231 images).
  • Device AP addressing is typically: device 10.10.123.3, your PC 10.10.123.4, UDP control on 48899.
  • After success, an AP named OpenBL602_xxxxxx appears; configure Wi‑Fi and set GPIOs (relays, buttons, LED).

Detailed problem analysis

How BL602 Wi‑Fi flashing works

  • BL602 OEM firmware in AP (provisioning) mode exposes:
    • a small DHCP server (hands out 10.10.123.x),
    • a UDP “AT” command port (48899),
    • an OTA updater that accepts a user‑supplied HTTP URL.
  • You leverage this by: 1) placing the correct OpenBeken OTA package on a local HTTP server, 2) sending AT+UPURL=… over UDP to point the device at your file, 3) waiting while it downloads, verifies, writes and reboots into OpenBeken.

Why the file type matters

  • BL602 uses Bouffalo’s RBL image format for “full” flashes and a compressed OTA container for over‑the‑air upgrades. Use the OpenBeken “OTA” image for Wi‑Fi flashing; the raw .rbl is for serial flashing. Images built for BK7231 (BK/Tuya) are not compatible with BL602 and must not be used.

Network/topology details

  • When in AP mode, the device SSID is often BL602_xxxxxx (naming can vary). After you join that AP:
    • device: 10.10.123.3 (fixed),
    • your computer: 10.10.123.4 (via device DHCP),
    • you host a simple HTTP server on your PC (for example, port 1111),
    • you send AT over UDP to 10.10.123.3:48899 with the URL to http://10.10.123.4:1111/…
  • During OTA you typically see responses like +ok=back ok and finally +ok=up_success. A reboot follows.

Step-by-step, end-to-end 1) Prepare files and tools

  • Download the OpenBeken OTA file for BL602 (filename ends with .ota; size a few hundred kB).
  • Have a simple HTTP server and a UDP sender:
    • Linux/macOS: nc (netcat) is usually available.
    • Windows: use ncat (from Nmap) or PowerShell/WSL to run nc and a simple HTTP server.

2) Put the switch into AP/pairing mode

  • Power it safely (see Safety below).
  • Hold a button 5–10 s until the LED blinks rapidly, or power‑cycle 3–5 times quickly to force pairing mode.
  • Your Wi‑Fi list should show a new AP (e.g., BL602_xxxxxx). Connect to it (2.4 GHz only).

3) Start a simple HTTP server that serves the OTA file

  • Put the OTA file (e.g., OpenBL602_…_OTA.bin.xz.ota) in an empty folder.
  • Serve it locally, e.g. with a minimal HTTP responder. Any simple static HTTP server is fine; ensure the server listens on all interfaces of the Wi‑Fi adapter assigned 10.10.123.4.

4) Tell the device to update (AT over UDP)

  • From your PC (while connected to the device AP), send:
  • Send it via UDP to 10.10.123.3 port 48899.
  • Wait. Typical responses:
    • Immediate acknowledgement,
    • after download/write: +ok=up_success,
    • device reboots automatically.

5) First boot into OpenBeken

  • The device creates an AP: OpenBL602_xxxxxx (default password often 12345678).
  • Join this AP and browse to http://192.168.4.1.
  • Enter your home 2.4 GHz SSID/password and save; after reboot the device joins your LAN. Find its IP in your router’s DHCP list.

6) Configure GPIO roles (template)

  • In OpenBeken web UI, set pin roles for CK-BL602-4SW-WH. Known working mapping:
    • Relays: P6, P7, P8, P9 → Relay (4 channels)
    • Buttons: P17, P13, P14, P18 → Button
    • Status LED: P11 → LED_n (inverted)
  • Save and reboot; verify:
    • buttons toggle the correct relays,
    • web UI controls each relay,
    • LED indicates Wi‑Fi/link state.

What if AT/OTA is blocked?

  • Some newer OEM firmwares disable the OTA URL or UDP AT port. In that case, Wi‑Fi flashing will fail (no response to AT, or update rejected).
  • Alternatives that sometimes work on other ecosystems (e.g., “cloud-cutter”-style SSID/DNS redirection) are generally not applicable if BL602’s AT path is closed.
  • Fallback: serial flashing with Bouffalo tools (requires opening the device, boot strap pins, USB‑UART, and flashing the .rbl image).

Current information and trends

  • Community firmware (OpenBeken) provides an actively maintained BL602 target with frequent builds (OTA and full images).
  • Manufacturers increasingly lock down OTA/AT paths in late 2023–2025 batches. Expect a rising share of units where Wi‑Fi flashing is blocked, making UART the only path.
  • Templates for popular BL602 boards (including multi‑gang wall switches) are now built into OpenBeken; many devices self‑identify or can import templates directly from the UI.

Supporting explanations and details

  • UDP AT control: The port 48899 mechanism originates from low‑cost IoT modules for provisioning and basic control; during AP mode it’s often left open to accept simple ASCII AT commands. AT+UPURL=… instructs the bootloader/updater to download an image from a specified HTTP URL.
  • OTA image specifics: The .ota container includes metadata and a compressed payload suited for the device-side updater. Do not rename or decompress the file; serve it as-is.
  • Minimal HTTP server: You only need correct Content-Length and body; many simple servers (python -m http.server, busybox httpd, ncat with a header preamble) are sufficient.

Ethical and legal aspects

  • Flashing custom firmware may void warranty and can violate vendor terms of service.
  • Ensure local regulatory compliance for RF devices (FCC/CE) after modification; keep default TX parameters and country codes.
  • Secure the device post-flash: set a strong admin password, avoid exposing the web UI to the internet, prefer TLS with MQTT when available.

Practical guidelines

Implementation methods

  • Preferred: AT+UPURL OTA method in AP mode (fast, no tools beyond a browser, nc, and a simple server).
  • If your PC lacks nc/ncat, use a small cross‑platform UDP send utility; ensure your firewall allows outbound UDP to 10.10.123.3:48899 and inbound TCP to your chosen HTTP port.

Best practices

  • Bench flash before in‑wall installation.
  • Label each relay channel after mapping; use the web console logs to confirm button/relay events.
  • Keep a copy of the exact OTA file used for future rollback within OpenBeken (OTA upgrades/downgrades are then trivial).

Potential challenges and how to overcome them

  • No +ok response to AT: confirm you are on the device AP, correct IPs (device .3 / PC .4), and that your firewall allows UDP.
  • OTA download stalls: check that the HTTP server is bound to the correct interface and port; large captive portals/VPNs can interfere—disable them temporarily.
  • After flash no OpenBL602 AP appears: wait 60–90 s; then power‑cycle once. If still absent, the flash may have failed—retry. Persistent failure implies a blocked OTA path or incompatible image.

Safety when powering the switch

  • This is a mains device. Use an isolation transformer or a safe test cord with an inline switch and RCD/GFCI protection. Never handle bare conductors while powered. If you are not comfortable with mains safety practices, do not proceed.

Possible disclaimers or additional notes

  • Not all CK-BL602-4SW-WH units are flashable over Wi‑Fi; vendor firmware revisions differ by production lot.
  • Some older guides mention BK7231 images or tools—those are for a different SoC and must not be used on BL602.
  • Reverting to factory firmware is generally not possible unless you first obtained a full flash backup via serial.

Suggestions for further research

  • Review OpenBeken’s BL602 documentation for the current OTA filename conventions and any device-specific caveats.
  • Check community device templates for CK-BL602-4SW-WH in case of hardware revisions changing GPIO assignments.
  • If Wi‑Fi flashing fails, read Bouffalo’s BLDevCube/BLFlashCommand user guides for serial recovery.

Brief summary

  • Put the CK-BL602-4SW-WH into AP mode, connect to its AP, host the proper OpenBeken BL602 .ota image on your PC, and send AT+UPURL over UDP to trigger OTA. After reboot, join the OpenBL602 AP, go to 192.168.4.1, connect it to your Wi‑Fi, and set the GPIO template. If the device’s OEM firmware has locked the OTA/AT path, Wi‑Fi flashing won’t work; use serial flashing with the .rbl image instead.

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