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[BKN7231N CBU] Universal remote control with temperature and humidity sensor

ststefanov 2361 22
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  • #1 20485704
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    Bought from here:
    https://www.aliexpress.com/item/1005004762491352.html
    Aliexpress page cache:
    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    Almost same as https://www.elektroda.com/rtvforum/topic3933390.html, but with added temperature and humidity sensor

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    Used GPIO pins are:
    P15 - Power IR receiver
    P17 - Red LED
    P9 - Green LED
    P28 - Reset button
    P24 - IR receiver input
    P26 - Sensor SCL
    P6 - Sensor SDA
    P7 - Sensor Alert
    P8 - IR send

    Temperature and humidity sensor is CHT8305. Datasheet is here:
    http://www.lanftek.com/Data/lanftek/upload/file/20180618/201802281014097175.pdf
    [BKN7231N CBU] Universal remote control with temperature and humidity sensor
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  • #2 20485957
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14393
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    Hello, maybe it's SHT30? With I2C and an alert line? What do you think, @dheenhasty ?

    Maybe you could try assigning SHT roles to the pins, with 3 pins and 2 roles, there are not many combinations to try...
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  • #3 20486043
    ststefanov
    Level 9  
    Posts: 15
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    I found it. It's CHT8305.
    Unfortunately, I'm new with OpenBK7231N and still I don't know how to configure it for this device.
    Does OpenBK7231N support CHT8305?
  • #4 20486283
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14393
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    Yes, just set the correct pin roles for SDA and SCL, furthermore, set first channel for SDA to 1 and second to 2 or smth like that.
    Btw:
    https://github.com/openshwprojects/OpenBK7231T_App/tree/main/docs
    Search for CHT8305 in the page below:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/ioRoles.md
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  • #5 20488084
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    GUI flasher doesn't work with my Debian Linux with several USB to TTL converters.
    Flashed successfully with uartprogram.
    I set pins for IR Send and Receive, also for CHT8305, but no data is appeared in the logs. Seems the driver is not yet finished.
    I'll check again pin numbers and functions.
    How to check CHT8305 and IR send/receive with HomeAssistant?
  • #6 20490171
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    I want to sincerely thank you @p.kaczmarek2 for your work on OpenBeken!

    I'm new to this forum and am also trying to use it on this same device. I have read your suggestions @p.kaczmarek2 but I too am unable to get this ir blaster /temp/humidity sensor to function.
    @ststefanov Could you share some screenshots of your settings? I'm confused about what I should put for P15 and P24 for instance since they both deal with the IR Receiver function. Also I don't know how to input P7.

    Thank you both for your help. I sincerely appreciate it.

    Added after 5 [minutes]:

    This is my current configuration (which doesn't work) [BKN7231N CBU] Universal remote control with temperature and humidity sensor
  • #7 20491150
    p.kaczmarek2
    Moderator Smart Home  
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    Setting CLK and DAT pins for CHT8305 should be enough, but of course you also have to restart.. Then you can also make sure to set two different channels for DAT pin, first will store humidity, second temperature.
    If CHT8305 is not responding, then you might have chosen incorrect GPIO.
    Check with multimeter which GPIOs are connected to CHT8305. Consult documentation of WiFi module/chip if needed.
    CHT8305 driver was tested and reported to be working by our users in the past.

    To check IRRecv, set correct pin for IRRecv, restart device, and open Web Application->Log and look at logs while pressing remote button.




    @strone8 , you need to check with multimeter or by following traces, where the IRReceiver/sender are connected. What do you mean with "both pins deal with receiver function"? The IRRecv is just a single pin. What is the role of P7 in case of your device?
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  • #8 20491268
    dheenhasty
    Level 13  
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    >>20485957
    Seems like cht has an alert mode too but less complex than the sht :)
    Both are really similar.
  • #9 20491339
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    Thank you @p.kaczmarek2 so much. I did follow your steps in tracing and I am sure that I was initially wrong and P24 is actually the IRRecv pin from multimeter tracing.

    For some reason I am not seeing any changes in the logs with IR remote presses despite having all logging features and levels fully enabled. I have some familiarity with this procedure on a separate device previously in Tasmota using an ESP8266.

    @ststefanov had listed "P15 - Power IR receiver" and "P24 - IR receiver input" and I am still unsure how to address "P15 - Power IR receiver" in the settings or if that's even necessary.

    Following @ststefanov I tried both the CHT SDA (P6) and CHT SCK (P26) as well as Soft SDA (P6) and SoftSDL (P26) and even with channel 1 and channel 2 selected for P6, I am getting "0.00" information for each.

    Any advice you can give would be greatly appreciated.

    Added after 12 [minutes]:

    An update: @dheenhasty thank you! I changed from CHT [BKN7231N CBU] Universal remote control with temperature and humidity sensor to SHT and I am now getting activity. The readings are totally off: I am 21C with 27% humidity but at least I have somewhere to start looking for calibration.

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor
  • #10 20491434
    dheenhasty
    Level 13  
    Posts: 111
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    The value you got is the défaut value of the driver, i think you have a bad pin définition and this does not tell you you have a sht

    There close, but the i2c command is not the same.
  • #11 20499480
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    P15 is used as output to power IR receiver. Probably this is done to save power when the receiver is not needed.
    To receive IR signals we must first set P15 to 1, this will power up the receiver and all will work. Here is the part of the schematics:
    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    @strone8, I still don't have working configuration. Changing to SHT gives unreal results because of wrong sensor type. Calibration will not work here.

    I think there is a problem with CHT8305 support, because when I set SDA and SCL for example for SHT I see 2 drivers active. When I set them for CHT I see only one driver active.

    Edit (after some trials): Seems that driver for CHT8305 is not started (may be bug?). I enabled RAW TCP connection and using telnet start the driver manually:
    Code: text Expand Select all Copy to clipboard
    startDriver CHT8305
Info:SENSOR:DRV_CHT8304_init: ID: 59 59
Info:MAIN:Started CHT8305.

    Now everything is working fine!

    [BKN7231N CBU] Universal remote control with temperature and humidity sensor

    Unfortunately, after restart the driver was not started. I don't know if this is bug or feature. To start automatically the driver in startup command line I added:
    Code: text Expand Select all Copy to clipboard
    startDriver CHT8305


    Now after system restart the driver is started and works OK.
  • #12 20499755
    p.kaczmarek2
    Moderator Smart Home  
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    You are indeed correct. Well done, I was not aware about this little issue. The autostart of CHT8305 driver was indeed missing, most likely the CHT8305 driver contributor didn't include this in his pull request.

    I have fixed it now and the new release will up and running within next 15 minutes. Thank you for reporting, @ststefanov
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  • #13 20499834
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    Thank you!
    Next step is to make device to learn IR commands from existing remote, save them in memory and send them when needed.
    Something as a virtual IR remote.
    Is there some guides on this topic?
  • #14 20500175
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    Just want to thank you both @p.kaczmarek2 and @ststefanov. My unit is reading temperatures with the updated firmware.

    Please excuse my ignorance. I tried setting P15 to 1 from 0 and switching the role to power but I must be doing something wrong. [BKN7231N CBU] Universal remote control with temperature and humidity sensor
    I saw the schematic do I need to make a physical change or software?
    Thank you again!
  • #15 20500323
    p.kaczmarek2
    Moderator Smart Home  
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    If you want P15 to be High all time, just set the pin role to "AlwaysHigh". Then it will always have a 3.3V on it.
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/ioRoles.md
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  • #16 20500332
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    @p.kaczmarek2 thank you!!!
  • #17 20500369
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    It was made intentionally this way. The IR receiver is used only in the learning process, which takes a very small amount of time compared to working time. All other time it is switched off to not consume power.
    If you like, you can assign LED or RELAY to P15 and switch it ON manually before learning. After learning is finished you can switch it off manually.

    I'm still searching how to learn and reproduce IR codes for air conditioning systems, for example.
  • #18 20500373
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    Thank you both so much for your replies! @ststefanov I'd like to hear about your progress and I'll share mine. I appreciate your help immensely
  • #19 20500379
    p.kaczmarek2
    Moderator Smart Home  
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    There is a WIP IR library extension but someone must look into flash memory issue on N platform:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/723
    Do anyone know how much power in reality that IR turn off really saves?
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  • #20 20500390
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    In the TSPO1738 datasheet typical current is 5mA, which means 16.5mW wasted (on more time) power. Another idea why they made this way is that along power saving most important is to switch off receiver when send IR commands. Due to high power of transmitter receiver always repeats sent IR signal and may be this created problems in the system. Powering from GPIO allows to enable and disable the IR receiver easily.

    Added later:
    May be the most important reason to keep things cool as much as possible is the presence of a thermo-sensor in the same case.
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  • #21 20513689
    ststefanov
    Level 9  
    Posts: 15
    Rate: 6
    Unfortunately my device is not responding anymore, maybe I fried it.
    So, when I have a new one I will continue with IR codes. Current device will be transformed in Tasmota with ESP-12F module.
  • #22 20514055
    strone8
    Level 6  
    Posts: 6
    Rate: 1
    @ststefanov Hope the other one works well for you and thank you for the guidance.

    Mine is still working and I initially thought about going the same route as you. I'm using the GPIO power set as a relay for IR learning and have the Red LED on to indicate that it's in that mode, with the green LED having inverted logic to indicate WiFi connection.

    I have a combination IR/RF Blaster (UFO-R2-RF) that I had to put an ESP8266 module into because it came with a WR3E module that currently isn't supported with OpenBeken or Tasmota.

    I need to investigate the RF portion on the UFO that I was having trouble with. The IR portion is always on but I believe the RF is GPIO powered so I will test that.
  • #23 20588159
    DeDaMrAz
    Level 22  
    Posts: 594
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    To compliment the CHT driver, a CHT_Cycle command has been added with 1.17.119 build - usage:

    //CHT_Cycle (sample time in seconds)
    CHT_Cycle 60

    You can add this in autoexec.bat script and adapt to your needs.
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Topic summary

✨ The discussion revolves around the configuration and functionality of the BKN7231N CBU universal remote control equipped with a CHT8305 temperature and humidity sensor. Users share insights on setting up GPIO pins for IR transmission and sensor communication, troubleshooting issues with the OpenBK7231N firmware, and ensuring proper driver activation for the CHT8305. Key challenges include configuring pin roles, ensuring the IR receiver is powered correctly, and verifying sensor data output. Solutions involve using multimeters for GPIO tracing, adjusting pin settings, and manually starting the CHT8305 driver. Users express gratitude for community support and share experiences with firmware updates and device functionality.
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FAQ

TL;DR: 16.5 mW can be saved by powering down the TSOP1738 IR receiver [Elektroda, ststefanov, post #20500390]; "the new release will be up and running within next 15 minutes" [Elektroda, p.kaczmarek2, post #20499755] The fix enables automatic CHT8305 sensor startup.

Why it matters: These tweaks cut standby power and unlock reliable temperature/humidity telemetry in OpenBeken-flashed IR blasters.

Quick Facts

• CHT8305 accuracy: ±0.5 °C & ±3 % RH [CHT8305 Datasheet]. • Operating voltage: 1.8 – 5.5 V, I²C up to 400 kHz [CHT8305 Datasheet]. • New CHT_Cycle command (build 1.17.119) sets 1 – 3600 s sample rate [Elektroda, DeDaMrAz, post #20588159] • IR receiver idle current 5 mA ⇒ 16.5 mW @ 3.3 V [Elektroda, ststefanov, post #20500390] • Linux flashing: uartprogram works when GUI flasher fails [Elektroda, ststefanov, post #20488084]

1. Which GPIOs does the BKN7231N CBU board use?

P15 = IR receiver power, P17 = Red LED, P9 = Green LED, P28 = Reset button, P24 = IRRecv, P8 = IRSend, P6 = CHT8305 SDA, P26 = CHT8305 SCL, P7 = CHT8305 Alert [Elektroda, ststefanov, post #20485704]

2. Does OpenBeken support the CHT8305 sensor?

Yes. Setting SDA and SCL roles starts the driver; support was confirmed by users and fixed to autostart in March 2023 [Elektroda, p.kaczmarek2, #20486283; #20499755].

3. Why did the driver fail to start before build 1.17.119?

The contributor forgot to register CHT8305 for autostart. Users had to run startDriver CHT8305 manually or via autoexec until the bug was patched [Elektroda, ststefanov, #20499480; p.kaczmarek2, #20499755].

4. How do I make CHT8305 readings appear?

  1. Assign roles: P6→CHT SDA, P26→CHT SCL.
  2. Reboot.
  3. Verify two channels (humidity then temperature) appear in Web→Log. If zeros persist, confirm pin routing with a multimeter [Elektroda, p.kaczmarek2, post #20491150]

5. What is CHT_Cycle and when should I use it?

CHT_Cycle n sets the sampling period to n seconds (e.g., CHT_Cycle 60 logs once per minute). Add the command to autoexec.bat for persistence [Elektroda, DeDaMrAz, post #20588159]

6. How do I power the IR receiver?

Set P15 to role AlwaysHigh to supply 3.3 V constantly, or map it as a relay so you can enable power only during learning sessions [Elektroda, p.kaczmarek2, #20500323; ststefanov, #20500369].

7. How much energy does disabling the IR receiver save?

The TSOP1738 draws 5 mA; turning it off saves about 16.5 mW continuously—roughly 0.4 Wh per day [Elektroda, ststefanov, post #20500390]

8. How do I test IR reception in OpenBeken?

Assign P24→IRRecv, reboot, open Web→Log, press a remote key, and watch for hex codes. No log output means wrong pin or P15 not high [Elektroda, p.kaczmarek2, post #20491150]

9. Can the board learn and replay air-conditioner codes?

Learning works; replay is Work-In-Progress due to flash-memory limits on BK7231N (see pull request #723). You can store raw frames now but advanced HVAC protocols need further coding [Elektroda, p.kaczmarek2, post #20500379]

10. How do I flash firmware from Debian Linux?

GUI flasher may not detect USB-TTL adapters; use uartprogram with 3.3 V RX/TX and reset the module into boot mode. Users reported success on several adapters [Elektroda, ststefanov, post #20488084]

11. Why do I read 0 °C and 0 % RH?

That means the driver is running but I²C lines are floating. Verify correct GPIOs and that CHT8305’s VDD is 3.3 V. Misassigned pins give default placeholder values [Elektroda, dheenhasty, post #20491434]

12. What edge cases can brick the unit?

Reverse-powering a GPIO or shorting 3.3 V can fry the BK7231N; one user lost the board after experiments and moved to an ESP-12F retrofit [Elektroda, ststefanov, post #20513689]

13. How do I keep IR noise from corrupting sensor readings?

Disable P15 while transmitting IR. This stops the receiver from echoing high-power bursts and prevents MCU overload [Elektroda, ststefanov, post #20500390]

14. Can I calibrate bad readings by switching to the SHT driver?

No. Using SHT roles on a CHT8305 only returns default constants, not real data. Correct the pin roles instead [Elektroda, dheenhasty, post #20491434]

15. Where is the documentation for pin roles?

OpenBeken lists every role, including AlwaysHigh, SoftSDA, and IRRecv, in ioRoles.md on GitHub [OpenBeken Docs].
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