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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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  • #31 20455491
    p.kaczmarek2
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    To publish state every minute use:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
    You can also put:
    Code: text Expand Select all Copy to clipboard
    
mqtt_broadcastInterval SECONDSNUMBER

    in autoexec, replace SECONDSNUMBER with for example 120 for 120 seconds.

    Code: text Expand Select all Copy to clipboard
    
1. data via mqtt can only be received until the module is rebooted, after rebooting it is necessary to enter the channel type again, for some reason they are not saved.

    Where do you set channel types?
    Then in autoexec do:
    Code: text Expand Select all Copy to clipboard
    
setChannelType 0 Temperature_div10
setChannelType 1 Humidity
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  • #32 20455518
    yuretskor
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    Thanks, I'll try it at home.
    I changed the flag type data via the web interface. After that, I pressed the save button, and the data was saved only after 3-4 reboots.

    Added after 2 [minutes]:

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

    Added after 27 [minutes]:

    Tell me I have a display on the TM1637 processor, it is not supported by the firmware. Is it possible to somehow add it? ready to be a tester)

    it would not be bad to display in a circle Time (21:45), Temperature (-7 °), Humidity (H 99) with a change interval of 5-10 seconds, well, this is of course a dream))
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?[/url]

    Added after 6 [hours] 4 [minutes]:

    Thank you. Now it works as it should. I will now connect the led module. Is it really possible to implement the change of the module colors on the temperature? [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
  • #33 20456240
    p.kaczmarek2
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    Very nice idea with display. I will check if I can order one like that in Poland and try to add support for you.

    Quote:
    module colors on the temperature

    It should be possible, but do you mean LED color? Do you have basic LED controls running?
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  • #34 20456257
    yuretskor
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    I took the wblc5 module from the led lamp. I have this type of LED module. I think it will not be a problem to order the tm1633 module in Ukraine, they are like dirt.
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
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  • #35 20456624
    p.kaczmarek2
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    Your device is using SM2135 LED driver. This LED driver supports 5 channels, so RGBCW is possible, but only requires 2 lines to work - SDA and SCL. It's using modified I2C protocol.
    Here is the pinout:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
    Communication is using DATA (SDA) and CLK (SCL) pins.
    Your wifi module, on other hand, has those pins:
    3PWM4I/OHardware PWM pin, which is connected to the P24 pin on the internal IC
    4PWM5I/OHardware PWM pin, which is connected to the P26 pin on the internal IC
    5PWM0I/OHardware PWM pin, which is connected to the P6 pin on the internal IC

    My question: can you take a look at the PCB traces or check with multimeter where the CLK and DAT are connected? To which Px of WiFi module?

    Of course, disconnect power before doing that!
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  • #36 20456657
    yuretskor
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    CLK -- PWM5, DATA(SDA) -- PWM4. If I now connected sht30 to Rx1 and Tx1, then it will not work to control the led?
  • #37 20456669
    p.kaczmarek2
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    SHT30 won't hurt for LEDs. It should be ok.

    Ok, so now, in pins config:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
    and reboot...
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  • #38 20456692
    yuretskor
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    Thanks, I will try. Now the module is soldered separately from the power board. In order for everything to work, you need to solder it and connect the power for sht30 and bring it out through the lamp housing. But I drank alcohol today and I don’t want to get drunk into 220 V circuits. I’ll be there tomorrow. Thanks, I'll write back tomorrow.
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    #39 20456793
    p.kaczmarek2
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    There is no need to hurry. I will be here tomorrow to help you.

    Once you start the driver, you will most likely see that the colors are swapped. White warm instead of blue, etc, etc. We will remap them with console command.

    Then we can try to write a channel change handler that will remap the temperature or whatever you want to a hue value or something like that.... I'll think about it.

    Added after 10 [minutes]:

    EDIT: I've bought that display with a donation money:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
    I will try to get it running once it arrives, but I can't promise anything.
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  • #40 20457482
    yuretskor
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    Connected as you suggested. Led doesn't work. (
    Everything is very expensive for you.

    Added after 1 [hour] 10 [minutes]:

    Now I have a sht30 sensor connected I
    I connect the led module to the sm2135e when you press Toggle light for a few seconds, the value of channel 1 changes from the current humidity to 100 and then returns back. In this case, the led module does not turn on.


  • #41 20457713
    p.kaczmarek2
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    Please test the LED driver directly by using the SM2135_RGBCW command.
    So something like:
    Code: text Expand Select all Copy to clipboard
    
SM2135_RGBCW FF00000000

    and then:

    Code: text Expand Select all Copy to clipboard
    
SM2135_RGBCW 00FF000000

    etc.

    The following command writes to LED directly and skips channels.
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  • #42 20457747
    yuretskor
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    Not work( [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?

    Added after 10 [minutes]:

    Maybe you need to use the SM2135_Current command to raise the current to 10, for example?

    Added after 42 [minutes]:

    And again the channel type has changed, I set the temperature to div10 after a reboot, it changes to the humidity of div10. Channel type change via web
  • #43 20457907
    p.kaczmarek2
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    SM2135_Current default value is correct.
    Nothing works? Not even:
    Code: text Expand Select all Copy to clipboard
    
SM2135_RGBCW 000000FF00

    or
    Code: text Expand Select all Copy to clipboard
    
SM2135_RGBCW 0000FF0000

    or
    Code: text Expand Select all Copy to clipboard
    
SM2135_RGBCW 00000000FF

    ?
    That would mean that maybe SDA and SCL are swapped (you need to reboot after changing).
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  • #44 20458002
    yuretskor
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    The led module started working after I removed autoexec.bat with the following code.

    Code: text Expand Select all Copy to clipboard
    echo "activate SHT3X Sensor"
startDriver SHT3X
setChannelType 0 Temperature_div10
setChannelType 1 Humidity
addRepeatingEvent 5 -1 SHT_Measure
mqtt_broadcastInterval 5


    SHT30 does not work at the same time ((and I see that when adjusting the color, the data changes in channel 2, where the humidity data is. Could this be the reason?

    Added after 10 [minutes]:

    and the colors don't match. I put Red - Blue, Blue - Green, Green - Red. What is C and W
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  • #45 20458050
    p.kaczmarek2
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    This command allows you to remap channel indexes:
    Code: text Expand Select all Copy to clipboard
    
SM2135_Map 2 1 0 4 3 

    it can be run once, without autoexec, it will remember the setting.
    You must guess which are the indexes.

    I am not sure about SHT30, fix colors first and then we'll think about it.
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  • #46 20458059
    yuretskor
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    Reboot after change?
  • #47 20458088
    p.kaczmarek2
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    No, in this case no reboot is indeed. But to see the new colors, you need to change something on web panel, move slider, select another color, toggle light. But no reboot needed.
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  • #48 20458089
    yuretskor
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    Adjusted colors Red - Red, Green - Green, Blue - Blue. The code is like this
    Code: text Expand Select all Copy to clipboard
    SM2135_Map 1 0 2 3 4

    The brightness is adjustable, but Cold - Warm does not work, as soon as I start to adjust the lamp turns off.
    That is, the central part of the lamp does not work only RGB LED
  • #49 20458094
    p.kaczmarek2
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    Maybe select this:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
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  • #50 20458108
    yuretskor
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    I turned on flag 9, the main LEDs started working and I entered the code for full-fledged work
    Code: text Expand Select all Copy to clipboard
    SM2135_Map 1 0 2 4 3

    only after applying the flag, the RGB LEDs began to shine dimmer, but within the normal range, I like it. I remove the flag, they do not become brighter. It will do for me anyway, this is for statistics) how now to make the temperature sensor SHT30 work as well? Maybe it needs to be transplanted to another channel, for example 5 temperature, 6 humidity? How to do it?
  • #51 20458931
    p.kaczmarek2
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    Can you try to change SHT channels to something unused, like 10 and 11:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?
    Also keep in mind that you need to change your old indices 0 and 1 in autoexec as well.
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    #52 20459103
    yuretskor
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    I can't figure out what's wrong with my module. Last night, the color red, blue, green, cold and warm worked separately. From the web interface. And the sensor worked separately. I turned it on in the morning, and the colors are not selected only by the RGB white channel. And it works cold and warm (only steel on the turn) if I send the command SM2135_RGBCW 000000FF00, then the color turns on. I send the command SM2135_Map 1 0 2 4 3 yesterday everything worked on it correctly yesterday, today it does not work anymore. As for the channels, I set 10 and 11 for sht30 led does not work at all (the temperature is transferred to these channels. Also I updated the firmware to the latest 499

    Added after 13 [minutes]:

    Sorry. Now connected from the computer, the color change works as it should. But not from the phone (although it worked yesterday. I'm in shock, honestly. Sorry again.

    Added after 18 [minutes]:

    Checked from a computer. The SHT3X-Sda-Scl adventure automatic temperature measurement operation function works. Just turn it on and work Led does not work.
  • #53 20459181
    p.kaczmarek2
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    I think I know what''s wrong. Thank you! Thanks to you I've found a potential issue that happens only when using LED driver with SHT driver. I will fix it for you in the next update. Please wait.

    @dheenhasty , do you know what happens? It's related to how I2C is handled...
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    #54 20459206
    dheenhasty
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    if Led driver is a 2135 i think i might have an idea. when you rework all the sensor /I2C stuff i find some SM2135 void in SHT Driver.

    So i suppose maybe we have some cross variable here ....
  • #55 20459212
    p.kaczmarek2
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    The issue is because we're in a middle of transition to shared soft I2C code (because at first we had I2C code duplicated in each driver, btw, surprisingly, Tasmota still has that code duplication), but the:
    Code: text Expand Select all Copy to clipboard
    
int g_i2c_pin_clk = 0;
int g_i2c_pin_data = 1;

    are still shared and global. And I2C LED can be called from other thread than I2C sensor...

    I will change the I2C code to use a local variable with a struct with two pin indices so there are no global variables anymore.

    @dheenhasty will you be able to test my changes later today?
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  • #56 20459219
    dheenhasty
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    Sure no problem later today.

    and i saw that Soft_I2C_Start and Soft_I2C_Stop is declared on SM2135 driver, but with SM2135 variables in it. don't know yet if it can impact;
  • #57 20459236
    p.kaczmarek2
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    They were here only temporary, I was in process of moving them to drc_soft_i2c.c, which are they now since several hours.

    I am finalizing the transition right now:
    [BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?

    Added after 1 [hours] 17 [minutes]:

    @dheenhasty I have first tested my changes on BP5758 LED driver, they seem to work, so I pushed my changes to the main tree. Is the SHT still working for you?
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  • #58 20459500
    dheenhasty
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    Yes everything ok on SHT Side.
  • #59 20459538
    p.kaczmarek2
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    @yuretskor I don't know if it fixes your issue, but you can try updating to latest version

    But it most likely will, because earlier even the SDA/SCL lines were overwritten by one driver for the another driver...
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  • #60 20459873
    yuretskor
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    @p.kaczmarek2 yes. Now everything works as it should. Both the LED module and the sht30 sensor, just to send the readings correctly via mqtt, you need to change the channels, I set 10 and 11. Now everything is fine. Thanks a lot. So the firmware will be perfect. Still, now the rgb color change by temperature and the tm1637 display and then there will be a bomb in general. Cool guys, thanks very much!

    Added after 1 [minutes]:

    Tell me how to remove the data in the square?[BK7231T/WBLC5] How to attach SHT30 sensor to smart Tuya LED?

    Added after 14 [minutes]:

    And, for some reason, changing the color through the browser on Android smartphones does not work, in order to change the color, you need to select a color and click on the launch web application button, then the color changes. From the computer works immediately.
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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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