Qiachip Smart Switch - BK7231N / CB2S - interior, programming

p.kaczmarek2 67377 302

Treść została przetłumaczona

Zobacz oryginalną wersję tematu

Reply Cool? Ranking DIY | New topic

Notify about new articles

#301 21703356 28 Sep 2025 17:05

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

Topic author Helpful post? (0)

Post #301
21703356 28 Sep 2025 17:05

Tuya uses cheap components and without OpenBeken Power Save, your capacitors may degrade quickly: https://www.elektroda.com/rtvforum/topic3898805.html

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.
ADVERTISEMENT
#302 21703437 28 Sep 2025 18:19

Tilator Tilator

Level 11

Helpful post? (0)

Post #302
21703437 28 Sep 2025 18:19

p.kaczmarek2 wrote:
uya uses cheap components and without OpenBeken Power Save, your capacitors may degrade quickly

Thanks. That was important and I did not know it.

I have bought more than 10 of these devices. One of them did litteraly blow in my hands after just some minutes use. It was not even flashed with any other but original FW.

Afterwards I found out, the capacitor was damaged. It had flattened places both sides of it and I assume this was made by assembly robot. It was sqeezed slightly too much and broken already.

So - it's definitely not a witch hunt to warn people about these chinese devices.

B.T.W: Since it is this important, would it even be good idea to add this setting in Configure General/Flags?
#303 21706375 01 Oct 2025 10:48

Tilator Tilator

Level 11

Helpful post? (0)

Post #303
21706375 01 Oct 2025 10:48

One more thing about this chip temperature and device health:

Should internal temp also be reported in status query json as well as other important values?
Create an account, log in here. You will receive points by participating in discussions.
Join this discussion.

Install Elektroda application

Reply Cool? Ranking DIY | New topic

Notify about new articles

Report a violation of the law

Topic summary

The discussion centers on the teardown and custom firmware programming of the Qiachip Smart Switch featuring the CB2S module based on the BK7231N chip, distinct from the BK7231T. The main focus is on flashing the OpenBK7231N firmware to replace the original Tuya firmware, enabling MQTT and Home Assistant integration while avoiding dependence on manufacturer servers. Users report challenges in accessing solder pads due to the module's compact, sandwich-like PCB design, often requiring careful desoldering with flux, solder wick, or hot air. Programming requires connecting 3.3V, GND, RX, and TX lines, with optional use of the CEN pin for reset, though power cycling is a common reboot method. USB-to-UART converters such as CH340 are preferred over CP2102 or FTDI due to reported compatibility issues. Firmware flashing tools include hid_download_py and BekenWriter, with emphasis on performing full 2MB flash dumps for backup and analysis. Users encounter issues like CRC errors, device reboot loops, and WiFi AP disappearance, often linked to MAC address misconfiguration or corrupted flash sectors. Solutions involve flashing full-sized firmware with padding, restoring original MAC addresses, and using safe mode by rapid power cycling. The OpenBK7231N firmware is evolving with fixes for configuration stability, pin mapping, and API access via REST commands. Some devices with integrated TuyaMCU complicate flashing due to UART line conflicts. The community shares detailed soldering techniques, debugging steps, and firmware versions, noting that stability varies across devices and firmware releases. The discussion also touches on related devices like CB3S modules, BK7321N chips, and sensors with TuyaMCU, with ongoing efforts to support these in OpenBK7231 firmware and improve low-power operation and integration with Home Assistant.
Summary generated by the language model.

Home page
/
Forum
/
Smart Home
/
Smart Home IoT
/
Smart Home Devices
/
Qiachip Smart Switch - BK7231N / CB2S - interior, programming

FAQ

TL;DR: Most CB2S/BK7231N smart-switches draw just 60-80 mA at 5 V (“0.4 W in active mode” [Elektroda, p.kaczmarek2, post #20255222]) and can be locally flashed in ≤3 min; “PowerSave fixes random reboots on weak PSUs” [Elektroda, p.kaczmarek2, post #20359114] Why it matters: correct pin-mapping and reset timing end 90 % of “WriteSector 1 Failed” errors.

Quick Facts

• Default flash layout: 0x0 offset, 2 MB total [Elektroda, piratee, post #20546731]
• Stable current draw: 60–80 mA @5 V, 0.4 W [Elektroda, p.kaczmarek2, post #20255222]
• Safe reset pulse: CEN→GND for 200–300 ms [Elektroda, p.kaczmarek2, post #21368818]
• Working baud rates: 115 200–921 600 bps; start with 115 200 for long wires [Elektroda, gowthaml, post #20253678]
• PowerSave lowers Wi-Fi duty-cycle to ≈30 mA average [Elektroda, p.kaczmarek2, post #20359114]

How do I put a CB2S/BK7231N into flash mode?

Solder RX1 (P11), TX1 (P10), 3.3 V and GND; leave RX2/TX2 empty. 2. Run uartprogram, wait for “Getting bus…”. 3. Short CEN to GND for ~250 ms, then release. The tool shows “Gotten bus” when the chip is ready [Elektroda, piratee, post #20546731]

I get “WriteSector 1 Failed”. What fixes it?

Mismatched pins are the top cause. Many new CB2S boards silkscreen RX1/TX1 one pad down—verify with a multimeter [Elektroda, p.kaczmarek2, post #21368818] Also drop baud to 115 200 bps and keep wire length under 15 cm [Elektroda, gowthaml, post #20253678]

Which firmware type should I flash?

• BK7231 N → QIO binary at 0x0. • BK7231 T → UA binary at factory offset. Flashing the wrong type overwrites bootloader and bricks the module [Elektroda, p.kaczmarek2, post #20200373]

Can I power the module from the USB-TTL adapter?

Only for reading. Writes peak above 150 mA; most adapters sag and corrupt transfers. Feed 5 V to the board’s AMS1117 VIN or 3.3 V from a 300 mA LDO instead [Elektroda, p.kaczmarek2, post #20202405]

Device reboots after a minute—why?

Low-cost PSUs overheat at 0.4 W continuous. Add PowerSave to Short Startup and current falls to ≈30 mA, eliminating thermal resets [Elektroda, Lesnoi, #20359179; p.kaczmarek2, #20359114].

How do I map pins on a MK601 relay board?

Typical mapping: P26 → LED, P6 → Relay, P7 → Btn, P10 → Btn_n (S2). For a latch switch use role TglChanOnTgl on P10 [Elektroda, spin55, post #20357749]

Why does Wi-Fi connect to SSID 1 but not SSID 2?

Secondary SSID fields are placeholder in current builds; only the first network is active [Elektroda, p.kaczmarek2, post #20964802]

How can I read Tuya-MCU sensors like DHT11 with OpenBeken?

Set the pin role to DHT11 or DHT22. OBK exposes temperature on Channel 1 and humidity on Channel 2. Example: linkTuyaMCUOutputToChannel 1 val 1, then setChannelType 1 ReadOnly [Elektroda, p.kaczmarek2, post #20359448]

Edge case: two devices share the same MAC and vanish from LAN.

Router drops duplicate MACs, causing OBK memory exhaustion (<5 kB free) and HTTP lock-ups. Run Restore RF Config to generate a new unique MAC [Elektroda, p.kaczmarek2, post #20334753]

Quick 3-step OTA recovery after bad flash?

Power-cycle the unit 5 times to enter Safe Mode. 2. Connect to the temporary AP, open 192.168.4.1/app, press “Exit Safe Mode”. 3. Upload a known-good QIO binary via Web Upgrader [Elektroda, p.kaczmarek2, post #20334576]

Does OpenBeken support DS18B20?

Not yet. Current sensor driver set covers DHT11/21/22 and CHT8305. DS18B20 is on the roadmap; subscribe to GitHub issue #622 for progress (OpenBekenIOT).

Where can I download original Tuya firmware?

There is no public archive. You must read a full 2 MB dump from a still-working unit with bkWriter or hid_download_py and save it for yourself [Elektroda, piratee, post #20546731]