CB3S Module Compatibility: BK7231N vs BK7231T, Realtek, Bouffalo, ESP8266 Identification

User question

I have a cb3s that has a part number that makes me think it's not bk7231n. How do I determine compatibility

Artificial Intelligence Response

Direct answer to the question

• Short answer: A genuine CB3S is almost always BK7231N (or BK7231NL). To be sure, positively identify the SoC (chip) and then pick firmware that matches that SoC. The fastest, least-destructive way is to read the boot log over UART or query the chip with a tool (e.g., ltchiptool). If it reads BK7231N/NL, you’re compatible with OpenBeken/LibreTiny “BK7231N-class” builds; if it’s something else (BK7231T/Realtek/Bouffalo/ESP8266), choose the corresponding firmware or approach.
• Key points:
  • “CB3S-NL” implies BK7231NL (compatible with BK7231N-target builds).
  • If the module marking is not “CB3S” (e.g., WB2S, WR3, TYWE3S), it is a different module/SoC.
  • Do not flash ESP-only firmware (e.g., stock ESPHome/Tasmota builds) onto Beken parts; use OpenBeken or ESPHome via LibreTiny.

Detailed problem analysis

• Why part numbers can be confusing
  • Tuya/OEMs reuse footprints and silkscreens while changing silicon for supply reasons. CB3S is defined around BK7231N/NL, but similar-looking modules exist with BK7231T (WB2S family), Realtek RTL8710/RTL8720, Bouffalo BL602, or classic ESP8266 (TYWE3S).
  • “CB3S-NL” is a formal variant based on BK7231NL; functionally it aligns with the BK7231N firmware family.
• Robust identification workflow (least to most invasive) 1) Paper trail and labeling
  • Read the exact module silkscreen (e.g., “CB3S”, “CB3S-NL”). Photograph it.
  • Check the device’s datasheet/FCC internal photos for the model used.
  • In the Tuya/SmartLife app, note “Main Module” firmware family; it often hints at the platform. 2) UART boot log (recommended)
  • Connect a 3.3 V USB–TTL adapter to the module’s UART (GND, RX, TX; 3.3 V supply). Start at 115200 baud.
  • Power-cycle and capture the first few lines. Typical signatures:
    • BK7231N/NL: banner contains “BK7231N” (or identifies as bk7231n via tools).
    • BK7231T: will identify as 7231T.
    • Realtek: logs often refer to RTL8710/RTL8720 or distinct Realtek boot strings.
    • Bouffalo: “BL602” string.
  • Tools such as ltchiptool can probe and print the detected target (e.g., “bk7231n, 2MiB Flash, 256KiB RAM”). 3) Firmware image inspection (optional)
  • Read out flash (non-destructive) and search for platform strings; this corroborates UART findings. 4) Physical inspection under RF can (last resort)
  • Removing the shield lets you read the top-mark of the SoC (BK7231N/NL/T, RTL…, BL602, ESP8266).
• Compatibility matrix (decision tree)
  • If SoC = BK7231N or BK7231NL: Use OpenBeken or ESPHome via LibreTiny with BK7231N-class target. Full feature support and pinout matches CB3S docs.
  • If SoC = BK7231T: Use the BK7231T-specific builds of OpenBeken/LibreTiny. Similar, but binaries are not cross-compatible with N/NL.
  • If SoC = Realtek RTL8710/RTL8720: Use LibreTiny target for Realtek; ESPHome works via LibreTiny. Do not flash Beken images.
  • If SoC = Bouffalo BL602/TG7100C: Use a BL602-capable stack (e.g., OpenBL602/Tasmota-BL); not compatible with Beken images.
  • If SoC = ESP8266 (e.g., TYWE3S module): Use standard Tasmota/ESPHome (ESP8266 targets).
• Pinout note
  • CB3S keeps a consistent footprint/pin map across N/NL. UART and key GPIOs are in the same positions per the CB3S datasheet. BK7231T modules (e.g., WB2S) have a similar footprint but are different parts; do not assume interchangeability of firmware even if the pads line up.

Current information and trends

• Tuya’s CB3S documentation specifies BK7231N; the CB3S-NL variant specifies BK7231NL. Community reports continue to confirm that genuine CB3S/CB3S-NL are BK7231N-class devices.
• OpenBeken and LibreTiny have mature support for BK7231N/NL and BK7231T, and ESPHome-on-Beken via LibreTiny is now routine.
• OTA tools (e.g., tuya-cloudcutter) can sometimes identify/convert devices without soldering, but coverage depends on the device’s shipped firmware.

Supporting explanations and details

• BK7231N vs BK7231NL: NL is a minor variant within the same family; practical firmware compatibility is the same in community builds that target BK7231N.
• BK7231N vs BK7231T: Different SDKs/ROMs/flash maps; binaries are not drop-in compatible across N/T.
• Why UART identification is preferred: It’s deterministic, fast, and avoids mechanical risk; boot ROM banners and probe tools report the exact target.

Ethical and legal aspects

• Opening devices and flashing custom firmware can void warranty and may violate regulatory approvals if RF parameters are altered.
• Maintain original RF design (antenna, shielding) and region settings to remain compliant with local regulations.

Practical guidelines

• Safe UART procedure
  • Use 3.3 V only. Never apply 5 V to any pin.
  • Common settings: 115200 8N1. If no output, try 74880/38400 as fallbacks.
  • Ground reference must be shared between adapter and module.
• Minimal steps to a positive ID 1) Photograph silkscreen; note “CB3S” vs “CB3S-NL” or something else. 2) Hook up UART, capture boot log; or run ltchiptool scan. 3) Choose firmware target based on the reported SoC.
• If you plan to flash
  • Back up flash first where possible.
  • Use the correct target (BK7231N vs BK7231T vs Realtek/Bouffalo).
  • After first boot, verify GPIOs (relays/LEDs/buttons) and adjust mapping.

Possible disclaimers or additional notes

• Even within the same SoC family, OEMs route GPIOs differently; expect to remap pins in software.
• Some Tuya images lock/debug-mute the UART; power-cycle at cold start and attach early to catch boot ROM output.
• OTA conversion tools are not guaranteed for every firmware revision.

Suggestions for further research

• Check the CB3S/CB3S-NL datasheets for pinout and reference design.
• OpenBeken and LibreTiny documentation for the exact flashing steps and target selection.
• Community device templates for your specific product model (helps with GPIO mapping).

Brief summary

• Your CB3S is very likely BK7231N-class. Confirm by reading the UART boot banner or probing with ltchiptool; then select the matching firmware target (BK7231N/NL vs alternatives). Do not cross-flash N/T/Realtek/Bouffalo/ESP targets. If you share your exact silkscreen/part number (and, ideally, a short boot log), I can tell you precisely which target to use and provide a tailored flashing sequence.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.