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[BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?

yuretskor 9840 97
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How do I flash and configure a BK7231/WBLC5 Tuya LED lamp with an SHT30 so it works as a temperature and humidity meter?

Flash it with OpenBeken; the advice was to first back up the original firmware with BK7231GUIFlashTool, then write the BK7231T OpenBeken build over UART1 after soldering GND, 3.3 V, RX and TX [#20450395][#20450565] For the SHT30, start the SHT3X driver and use an autoexec script such as `startDriver SHT3X`, `setChannelType 0 Temperature_div10`, `setChannelType 1 Humidity`, and `addRepeatingEvent 5 -1 SHT_Measure`; if you want regular MQTT updates, add `mqtt_broadcastInterval 5` [#20454182][#20454498][#20455491] The sensor can be connected on the available pins, and if you keep the LED driver too, the thread later found a soft-I2C conflict that was fixed in a newer firmware build [#20459181][#20459212][#20459538] After updating, the combined LED + SHT30 setup worked, and moving the sensor to unused channels 10 and 11 solved the channel-clash/MQTT issues [#20458931][#20459873]
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  • #91 21204711
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14408
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    Yes yes, sorry, permission granted! And it seems it worked that time! All builds are successfull. https://github.com/openshwprojects/OpenBK7231T_App/pull/1333
    Helpful post? Buy me a coffee.
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  • #92 21204872
    yuretskor
    Level 7  
    Posts: 52
    Help: 1
    Rate: 1
    @p.kaczmarek2 Seriously, wouldn't it have been easier for you to give me a file with the TM 1637 driver included? I don't quite understand what I'm clicking on the site to create the firmware and I still have to wait for your approval. It's long and complicated. If anything, I'm sorry.

    Added after 24 [minutes]:

    Somehow I connected it, there is a shift of one sign. How to fix it?

    Added after 47 [minutes]:

    When I enter the command TMGN_print 0 0 1234 On the display I see what is in the photo below.
    LED display showing the number 321 on a wooden desk.
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  • #93 21205344
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14408
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    If digits order is not standard, then you need to try one of many TMGN_Map combinations.
    Start with:
    Code: text Expand Select all Copy to clipboard
    
TMGN_Map 01234567
TMGN_print 0 0 1234 

    check result, of course do print on screen after doing map command.
    If still wrong, try:
    Code: text Expand Select all Copy to clipboard
    
TMGN_Map 32104567
TMGN_print 0 0 1234 

    etc, etc.
    Here are docs:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/commands.md

    This is because the order of digits is not standarized in those modules.
    Helpful post? Buy me a coffee.
  • #94 21208643
    yuretskor
    Level 7  
    Posts: 52
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    @p.kaczmarek2 I don't know what the problem is, but the TMGN_map command doesn't work for me, or rather, with different combinations, the display changes from 321 to 32 and that's it. And if the TMGN_test command, it displays 1234 correctly and each time the command is sent, it shifts by three digits 3456 then 6789 and so on in a circle. And if I send the TMGN_print 0 0 1234 command, I see what's in the photo above.
    LED display showing the numbers 0123 on a wooden table.


    Added after 4 [minutes]:

    @p.kaczmarek2 and if I send the command TMGN_print 0 0 7654321 then I see 5672 on the screen Segment display showing the number 5672.

    Added after 40 [minutes]:

    If possible, help me via telegram, for faster communication. Nick yurets_kor
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  • #95 21210101
    yuretskor
    Level 7  
    Posts: 52
    Help: 1
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    Bad idea with the display. In general, I'll throw the project back in the drawer.
  • #96 21210175
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14408
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    You should not use TMGN_test for production. Just use:
    Code: text Expand Select all Copy to clipboard
    
TMGN_Map 32104567
TMGN_print 0 0 1234 

    Find the TMGN_Map that makes TMGN_print show 1234 correctly, I've seen you did that?
    Helpful post? Buy me a coffee.
  • #97 21210995
    yuretskor
    Level 7  
    Posts: 52
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    Rate: 1
    pkaczmarek2 I I tried entering the command TMGN_Map but the changes occur only once, subsequent times when the combination changes numbers nothing changes. Or after each input do I need to reboot? Today I can spin all day under your commands.
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  • #98 21305381
    yuretskor
    Level 7  
    Posts: 52
    Help: 1
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    Since yesterday, the module stopped transmitting data via mqtt, in the logs I see that it uses a password, but I use the service without a password, and to save the configuration, you need to put some sign. Probably because of this, he stopped transmitting. If you leave the password blank, the previous one will be used.
    It is not possible to save an empty field. Could you help? Thank you
    Code: text Expand Select all Copy to clipboard
    
Info:GEN:dhcp=0 ip=192.168.0.195 gate=192.168.0.1 mask=255.255.255.0 mac=84:e3:42:41:f8:6b
Info:GEN:sta: 1, softap: 0, b/g/n
Info:GEN:sta:rssi=-80,ssid=K.Y.A,bssid=ae:15:a2:4c:02:a6,channel=2,cipher_type:CCMP
Info:MAIN:Time 981, idle 207313/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:GEN:CHANNEL_Set channel 10 has changed to 210 (flags 0)

Info:MQTT:Channel has changed! Publishing 21.000000 to channel 10 
Info:GEN:No change in channel 11 (still set to 66) - ignoring

Info:SENSOR:SHT3X_Measure: Temperature:21.0C Humidity:66%
Info:MAIN:Time 982, idle 211407/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 983, idle 172131/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 2, socks 2/38 
Info:MAIN:Time 984, idle 220851/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 985, idle 209036/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 986, idle 199669/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 987, idle 182554/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 988, idle 192972/s, free 83816, MQTT 0(61), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MQTT:mqtt_userName yurets.kor
mqtt_pass 1234
mqtt_clientID obk8C000000
mqtt_host broker.hivemq.com:1883
Info:MAIN:Time 989, idle 220875/s, free 83728, MQTT 0(62), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:MAIN:Time 990, idle 219968/s, free 83728, MQTT 0(62), bWifi 1, secondsWithNoPing 1, socks 2/38 
Info:GEN:dhcp=0 ip=192.168.0.195 gate=192.168.0.1 mask=255.255.255.0 mac=84:e3:42:41:f8:6b
Info:GEN:sta: 1, softap: 0, b/g/n
Info:GEN:sta:rssi=-77,ssid=K.Y.A,bssid=ae:15:a2:4c:02:a6,channel=2,cipher_type:CCMP
Info:MQTT:MQTT base topic is dirty, will reinit callbacks and reconnect
Info:MQTT:MQTT_RegisterCallback called for bT obk8C000000/ subT obk8C000000/+/set
Info:MQTT:MQTT_RegisterCallback called for bT bekens/ subT bekens/+/set
Info:MQTT:MQTT_RegisterCallback called for bT cmnd/obk8C000000/ subT cmnd/obk8C000000/+
Info:MQTT:MQTT_RegisterCallback called for bT cmnd/bekens/ subT cmnd/bekens/+
Info:MQTT:MQTT_RegisterCallback called for bT obk8C000000/ subT obk8C000000/+/get
Info:MQTT:MQTT has pending reconnect in 4


    Added after 5 [minutes]:

    Removed the commands and connected. What's wrong?
    Code: text Expand Select all Copy to clipboard
    mqtt_broadcastInterval 2
mqtt_broadcastItemsPerSec 5


    Added after 4 [minutes]:

    Although the problem is that the readings are static, as soon as the sensor changes readings, it connects and sends data
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Topic summary

✨ The discussion focuses on integrating an SHT30 temperature and humidity sensor with a smart Tuya LED lamp module based on the BK7231T processor, specifically the WBLC5 module. The user seeks firmware and configuration guidance to repurpose the lamp as a temperature and humidity meter. The OpenBeken firmware is recommended, with detailed instructions on flashing, pin assignments (notably PWM0/P6, PWM4/P24, PWM5/P26 for I2C and LED control), and UART1 usage for programming. The SHT30 sensor is connected via software I2C on UART1 pins (Rx1/Tx1), requiring driver activation and scripting in the device's web interface (autoexec.bat or LittleFS scripts) to initiate periodic measurements. MQTT integration is addressed, including channel type settings, data publishing intervals, and troubleshooting MAC address issues. LED control uses the SM2135 LED driver with RGBCW channels over I2C (SDA on PWM4/P24, SCL on PWM5/P26), with commands for color mapping and brightness adjustment. Conflicts between LED and sensor I2C usage due to shared global variables were identified and resolved in firmware updates. The TM1637 4-digit display support was developed and integrated, allowing cyclic display of time, temperature, and humidity via scripting. Challenges with channel persistence after reboot, MQTT data resolution, and Android browser compatibility for color control were discussed and addressed through firmware updates. The conversation includes advanced scripting examples for event handling, channel mapping, and MQTT broadcast tuning. The user also encountered difficulties with TM1637 digit order and firmware compilation, receiving guidance and precompiled firmware with TM1637 support. Overall, the thread provides a comprehensive technical roadmap for customizing BK7231T-based Tuya LED modules with SHT30 sensors, LED color control, MQTT telemetry, and TM1637 display integration using OpenBeken firmware and scripting.
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FAQ

TL;DR: Flashing a WBLC5 (BK7231T) with OpenBeken takes about 15 minutes; “it’s very easy, it’s like 15 minutes job” [Elektroda, p.kaczmarek2, post #20450565] The SHT30 delivers ±0.2 °C accuracy and ±2 % RH [Sensirion DS, 2022]. Why it matters: one module lets you log temperature, humidity and drive RGB-CW LEDs over MQTT without Tuya cloud.

Quick Facts

• BK7231T UART1 pins = 3.3 V, GND, P24 (RX1), P26 (TX1) [Elektroda, p.kaczmarek2, post #20450565] • SHT30 supply: 2.4–5.5 V, 150 µA active, 0.5 µA sleep [Sensirion DS, 2022] • OpenBeken build ≥ 1.15.507 fixes I²C LED/SHT conflict [Elektroda, p.kaczmarek2, post #20459538] • SM2135 LED driver current default 10 mA per channel [Elektroda, p.kaczmarek2, post #20457907] • MQTT broadcast period set by mqtt_broadcastInterval SECONDS (range 1–86400) [OpenBeken Docs]

What firmware should I flash to a WBLC5/BK7231T to read an SHT30 sensor?

Use the current OpenBeken build for BK7231T. The easy flasher can download the correct binary automatically and backs up the factory image first [Elektroda, p.kaczmarek2, post #20450565]

How do I connect the module for flashing without powering the mains LED board?

  1. Solder 3.3 V, GND, RX1 (P24) and TX1 (P26) to a USB-UART adapter.
  2. Start “Backup firmware (read)” in BK7231 GUI Flash Tool.
  3. Power-cycle the module to enter bootloader, finish read, then write OpenBeken [Elektroda, p.kaczmarek2, post #20450565]

Which GPIO pins can I use for SHT30 SDA and SCL on a WBLC5?

Free pins are P6, P24 and P26. Most users place SDA on P24 (RX1) and SCL on P26 (TX1). Software I²C works on any of them after setting pin roles in the web UI [Elektroda, p.kaczmarek2, post #20452701]

Can I keep full LED functionality while running the SHT30?

Yes. Map SDA/SCL to UART1 pins for SHT30 and keep PWM4/PWM5 driving the SM2135 LED chip. Firmware ≥ 1.15.499 fixed the I²C conflict; update if LEDs go dark after sensor reads [Elektroda, p.kaczmarek2, post #20459181]

After entering Wi-Fi credentials the access point vanished—how do I find the module?

Once the device joins your WLAN it gets a new IP via DHCP. Scan your network or check the router for a hostname beginning with “obk…” [Elektroda, dheenhasty, post #20452636]

I wired the SHT30 but see no readings. What else is required?

Start the driver and schedule measurements: 

startDriver SHT3X
addRepeatingEvent 10 -1 SHT_Measure
Save these lines in autoexec.bat or the LittleFS editor, then reboot [Elektroda, p.kaczmarek2, post #20454182]

How do I make OpenBeken publish MQTT data every 60 s even when values don’t change?

Set persistent interval broadcasting: 

mqtt_broadcastInterval 60
mqtt_broadcastItemsPerSec 2
This forces a publish every 60 s per channel whether or not the reading changed [Elektroda, p.kaczmarek2, post #20455491]

My LEDs stopped responding after I added the sensor—what’s the fix?

Update to firmware ≥ 1.15.507, which separates I²C pin instances. Earlier builds overwrote LED SDA/SCL with SHT values, disabling SM2135 output [Elektroda, p.kaczmarek2, post #20459538]

LED colours are swapped; how do I remap SM2135 channels?

Run SM2135_Map r g b c w, replacing each letter with the desired index (0–4). Example for RGB-CW order: 

SM2135_Map 1 0 2 4 3
No reboot required; move any slider to view the change [Elektroda, yuretskor, post #20458108]

Edge-case: MQTT stops when temperature and humidity stay constant—why?

OpenBeken suppresses MQTT messages if No change in channel to save bandwidth [Elektroda, yuretskor, post #20454637] Override by lowering mqtt_broadcastInterval or forcing repeating events to push unchanged data.

Is TM1637 display supported and how do I wire it?

Support is merged; flash a build with #define USE_TM1637. Assign DIO and CLK pins in Web App, then print: 

TM1637_Print 0 0 $CH10 ;temperature
Use TMGN_Map to correct digit order if needed [Elektroda, p.kaczmarek2, post #21205344]

What if TM1637 digits appear out of order?

Send different TMGN_Map permutations until TMGN_Print 0 0 1234 shows 1234. Typical common-anode modules use TMGN_Map 32104567 [Elektroda, p.kaczmarek2, post #21205344]
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