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Integrating BME280 Sensor with OpenBK on WB2S Modules for Home Automation

bilbs84 6987 75
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Can I use a BME280 sensor with OpenBK on a WB2S module over software I2C, and how do I configure the pins, address, and Home Assistant publishing?

Yes — OpenBK can drive a BME280 on a WB2S using the BMP280/BMPI2C software-I2C driver, and the later BMPI2C version adds temperature, pressure, and humidity support [#20862222][#21123022] Use the `startDriver` command with your GPIOs and channel numbers; examples from the thread were `startDriver BMP280 [CLK] [DATA] [TempChan] [PressureChan]` and later `startDriver BMPI2C [CLK] [DATA] [Temp] [Pressure] [Humidity] [Addr]` [#20862067][#21123022] A working BME280 setup on a WB2S used `P7` as SDA and `P8` as SCL, with the sensor address set to `0x76` [#21112840] For Home Assistant, you can use channel types like `Temp_div100` and `Pressure_div100`, or publish manually with `publishFloat`; MQTT still carries the raw integer value unless you apply the divider/publish logic yourself [#20862313][#21013338] One important caveat is that the BME280 temperature reading is the chip’s internal temperature, so it can read a few degrees high and may need an offset calibration if you want it to represent room temperature [#20862559][#20862569]
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  • #31 20889503
    Alexpress
    Level 2  
    Posts: 2
    Rate: 1

    Hello and greetings to all. I am in the same case as my colleague bilbs84. The problem is that I am even newer to this and I have several WB2S modules, with OpenOBK installed and I want to integrate BME680 sensors and have these readings in Home Assistant. But no matter how much I have read on the internet, I don't see an easy way, for a beginner. Thanks again for your answers and greetings.
    P.S. Sorry for my English language, but I use a translator.
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  • #32 20889667
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14412
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    Rate: 12357
    BME680 or BME280? I haven't seen BME680 yet, I would need to buy one and try.
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  • #33 20890106
    Alexpress
    Level 2  
    Posts: 2
    Rate: 1

    Thanks for answering. It is BME680, which has some more features than 280. I bought them on Aliexpress at a good price, with the intention of integrating it with an ESP32 in home assistant, but since I have several CB2S with OpenBK, I wanted to see if it is possible.
    Here is a photo with the tests and Aliexpress link. BME680 and CB2S modules connected by wires on a white background.
    Greetings!

    https://es.aliexpress.com/item/10050059703827...t_main.11.21ef194dbFEnlm&gatewayAdapt=glo2esp
  • #34 20945270
    Osrx
    Level 5  
    Posts: 11

    Why did you take off the BMP280 driver code from current releases of OBK?
    I think it worked rather well for me. And I started trying to use it on my OpenBK7231N. =(

    Thank you for your work anyway! =)
  • #35 20945538
    p.kaczmarek2
    Moderator Smart Home  
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    I apologize for the confusion. The code is still here, but the driver may be disabled because we are slowly running out of the flash memory.

    If you want to get a build with BME280 driver, you need to add:
    Code: text Expand Select all Copy to clipboard
    
#define ENABLE_DRIVER_BMP280 1

    to obk_config.h .
    Alternatively, I can do the same for you, here:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/1064
    Once it builds, you can click into build results, scroll down to "Summary" and click "Download artifacts" to get a binary file with BMP280 support
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  • #37 20990186
    p.kaczmarek2
    Moderator Smart Home  
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    I apologize for the issue. It seems that something have randomly broken on Github:
    Code: text Expand Select all Copy to clipboard
    
../toolchain/gcc-arm-none-eabi-4_9-2015q1/bin/arm-none-eabi-objcopy -O binary ../../../apps/OpenBK7231T/output/BMP280-driver-enabled-fork_83eb11c040fc/OpenBK7231T_BMP280-driver-enabled-fork_83eb11c040fc.axf ../../../apps/OpenBK7231T/output/BMP280-driver-enabled-fork_83eb11c040fc/OpenBK7231T_BMP280-driver-enabled-fork_83eb11c040fc.bin
make[3]: Leaving directory '/home/runner/work/OpenBK7231T_App/OpenBK7231T_App/sdk/OpenBK7231T/platforms/bk7231t/bk7231t_os'
make[2]: Leaving directory '/home/runner/work/OpenBK7231T_App/OpenBK7231T_App/sdk/OpenBK7231T/platforms/bk7231t/bk7231t_os'
Start Combined
Combined will do cd
Combined will do OTAFIX
Combined will do ENCRYPT
/**< @author <jiewu@bekencorp.com> */
/**< @version v0.3.1 */
 encrypt without crc successfully!
 -file size: 0xc6df0
Combined will do mpytools.py
{
    "count": 4,
    "magic": "RT-Thread",
    "section": [
        {
            "firmware": "bootloader_enc.bin",
            "partition": "bootloader",
            "size": "68K",
            "start_addr": "0x00000000",
            "version": "1.00"
        },
        {
            "firmware": "OpenBK7231T_BMP280-driver-enabled-fork_83eb11c040fc_enc.bin",
            "partition": "app",
            "size": "978944",
            "start_addr": "0x00011000",
            "version": "1.00"
        }
    ],
    "version": "0.1"
}
Combined will do BEKEN_PACK
beken packager V2.1.0
Shanghai Real-Thread Electronic Technology Co.,Ltd
Linux-5.15.0-1057-azure-x86_64-with-Ubuntu-20.04-focal

load_config: config.json

partition    flash_name       phy addr   size       logic addr size       file
------------ ---------------- ---------- ---------- ---------- ---------- ----------------
bootloader   beken_onchip_crc 0x00000000 68K        0x00000000 64K        bootloader_enc.bin
app          beken_onchip_crc 0x00011000 956K       0x00010000 921359     OpenBK7231T_BMP280-driver-enabled-fork_83eb11c040fc_enc.bin

image size: 1024 KB
image name: all_1.00.bin

export app partition image: OpenBK7231T_BMP280-driver-enabled-fork_83eb11c040fc_enc_uart_1.00.bin

time: 0.95s
Good bye!
End Combined
generate ota file
malloc(): corrupted top size
Aborted (core dumped)
make[1]: *** [Makefile:107: build-BK7231] Error 134
make[1]: Leaving directory '/home/runner/work/OpenBK7231T_App/OpenBK7231T_App'
make: *** [Makefile:80: OpenBK7231T] Error 2
Error: Process completed with exit code 2.

    This is very strange! I don't know why it failed.

    I've recreated PR and here it is, it's working. Strange indeed:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/1111/files

    Now you can download build files from that PR.
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  • #38 21010592
    olekwal
    Level 6  
    Posts: 12

    Hello,
    Can this BME280 controller also be enabled in BL602? I would like to use the rx and tx pins for this (i2c to the sensor), I do not use them in "normal" mode. Is this even possible? And do you have to compile it yourself or is this driver included in normal builds?

    Thank you for the information.
  • #39 21010867
    p.kaczmarek2
    Moderator Smart Home  
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    BL602 is low on memory, BMP280 is not enabled there. You need to enable it and compile it yourself. Here is the configuration file:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/obk_config.h
    Here is #define:
    Code: text Expand Select all Copy to clipboard
    
//#define ENABLE_DRIVER_BMP280 1

    Here is an instruction to compile online on Github without installing anything on your computer:
    OpenBeken online builds system - firmware compilation for all platforms on Github
    Additionally, you may need to add missing files to the Makefile, but that will come out in the end. Try it, I`ll help you if you need it.
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  • #40 21011595
    olekwal
    Level 6  
    Posts: 12

    Oh, something`s not working for me....

    I forked the project, changed "#define ENABLE_DRIVER_BMP280 1" to "#define ENABLE_DRIVER_BMP280 1" in the obk_config.h file. It compiles without errors (this compiling function on GitHub is amazing, I wonder who pays for it...), I uploaded it to magichome with BL602.:
    In the webapp I enter: "startDriver BMP280 0 1 1 2" (I`m not sure about the pins, but this is a later issue)
    Quote:
    Info:MAIN :D river BMP280 is not known in this build.
    Info:MAIN:Available drivers:
    Info:MAIN:NTP
    Info:MAIN:, RN8209
    Info:MAIN:, BL0942
    Info:MAIN:, BL0937
    Info:MAIN:, CSE7766
    Info:MAIN:, DDP
    Info:MAIN:, SSDP
    Info:MAIN:, DGR
    Info:MAIN:, Wemo
    Info:MAIN:, SM2135
    Info:MAIN:, BP5758D
    Info:MAIN:, BP1658CJ
    Info:MAIN:, SM2235
    Info:CMD:[WebApp Cmd `startDriver BMP280 0 1 1 2` Result] OK


    ... looks like there is no driver.

    Second attempt: I looked at the obk_config.h file: there is its own part for BL602, so I added the driver there:
    Quote:
    #elif PLATFORM_BL602

    // I have enabled drivers on BL602
    #define ENABLE_TASMOTADEVICEGROUPS 1
    #define ENABLE_NTP 1
    #define ENABLE_DRIVER_LED 1
    //#define ENABLE_DRIVER_BL0937 1
    //#define ENABLE_DRIVER_BL0942 1
    //#define ENABLE_DRIVER_CSE7766 1
    #define ENABLE_DRIVER_WEMO 1
    #define ENABLE_DRIVER_BMP280 1


    Compilation without errors, but "Info:MAIN :D river BMP280 is not known in this build."

    Third attempt: I took the compiler from here: https://github.com/openshwprojects/OpenBK7231T_App/pull/1111 - I uploaded it, unfortunately the same thing again: "Driver BMP280 is not known in this build"

    It seems that the "#define ENABLE_DRIVER_BMP280 1" option is ignored when building the binary for BL602....
    Should the driver start like this? "startDriver BMP280 xx 1 2"?
  • #41 21011607
    p.kaczmarek2
    Moderator Smart Home  
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    This is strange, maybe something is missing. BL602 is rare and I`m only one person and it`s hard to understand such a large open source project.
    Then I`ll try it myself, here`s my PR:
    https://github.com/openshwprojects/OpenBK7231T_App/pull/1133
    It`s compiling now, in fifteen minutes I`ll check whether the compilation was successful or not. You may need to add something to the Makefile.

    Additionally, I would also be a bit afraid that the BMP280 would exceed the size of the OTA on the BL602 and there would be a problem with the update, but we`ll see.

    Added after 1 [minutes]:

    PS: And this:
    olekwal wrote:

    3rd attempt: I took the compiler from tad: https://github.com/openshwprojects/OpenBK7231T_App/pull/1111 - I uploaded it, unfortunately the same thing again: "Driver BMP280 is not known in this build"

    it 100% does not work on BL602, because the above PR is me who turned on BMP280 on the BK7231 platform. BK7231 is a separate platform. You have to look in obk_config.h for which platform you are enabling, because we support 5 platforms already (BK7231 two versions, W600, W800, BL602, XR809, LN882H and Windows... oh, that`s more than 5)

    Added after 8 [minutes]:

    I found the problem:
    Screenshot of a source code snippet in a text editor.
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  • #42 21011634
    olekwal
    Level 6  
    Posts: 12

    No, it's like yesterday (2nd attempt)

    There is apparently no problem with the build, it also works, after the update I have a new build number (Build: Build on Mar 20 2024 08:40:07 version bl602-bmp_0204362d2fcd)

    But when I type "startDriver BMP280 0 1 1 2" in the Logs section in the new webapp, I get:
    Quote:
    Info:MAIN :Driver BMP280 is not known in this build.
    Info:MAIN:Available drivers:
    Info:MAIN:NTP
    Info:MAIN:, RN8209
    Info:MAIN:, BL0942
    Info:MAIN:, BL0937
    Info:MAIN:, CSE7766
    Info:MAIN:, DDP
    Info:MAIN:, SSDP
    Info:MAIN:, DGR
    Info:MAIN:, Wemo
    Info:MAIN:, SM2135
    Info:MAIN:, BP5758D
    Info:MAIN:, BP1658CJ
    Info:MAIN:, SM2235
    Info:CMD:[WebApp Cmd `startDriver BMP280 0 1 1 2` Result] OK


    But really, it's not that important, it's more of a gimmickry, so there's no point in wasting your precious time on it.


    After update:
    Oh, I see. then this driver simply does not exist for bl602. At least everything is clear now :)
  • #43 21011662
    p.kaczmarek2
    Moderator Smart Home  
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    This controller uses I2C software, it should work with BL602 without any problems, have you checked the latest version from my PR?
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  • #44 21011686
    olekwal
    Level 6  
    Posts: 12
    yes, now I can load the driver.

    do you know what pins are rx and tx on bl602? I started looking for it, but I think I`ll miss it...
    oh, and one more thing: when using bme280 I have "info:SENSOR:BMx280 wrong ID!" but I read that the controller itself looks for the appropriate ID, so it`s just a matter of finding the right pins?

    OK: Update, I found the pins, (on bl602: p16 - scl; p7 -sda) everything works, great!
    what bmE280 still lacks is humidity. When I have some time, I`ll try to look at the code myself.

    Added after 2 [hours] 1 [minutes]:

    One more thing:

    How to change the measurement frequency? for now it measures (and sends via mqtt) every second...
  • #45 21012263
    p.kaczmarek2
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    Sorry. I didn`t get a notification after editing. You wrote earlier that it doesn`t publish on MQTT, but does it work?
    From what I can see, the measurement is actually made every second, to limit this I can add a few lines on the spot and give you a PR with it to download the ready binaries.
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  • #46 21013338
    olekwal
    Level 6  
    Posts: 12

    No problem. MQTT works. I just had to learn how openbk works. What is not optimal is: I set Temperature to channel 6 and pressure to channel 7. In channel types I set Temp_div100 to 6 and Pressure_div100 to 7 and the data format also matches on the web page. MQTT ignores this /100 - i.e. data enters "raw" via mqtt - e.g. 2660 instead of 26.60. But this is a detail - I can also do division by 100 on openhab.

    As for the bmp280 driver. If it was possible to change/add "startDriver BMP280 [CLK] [DATA] [ChannelForTemp] [ChannelForPressure]" with an additional field for the measurement frequency - e.g. "[measurementInterval] " in seconds, it would be perfect. hard-coded is also possible, I think it will be enough if it measures every 5 minutes, it makes a lot of noise every second....
  • #47 21013349
    p.kaczmarek2
    Moderator Smart Home  
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    There is a flag on the divider. It`s all because of the TuyaMCU standard that we based on at the beginning. Turn on:
    Screenshot of a feature list with a highlighted MQTT feature: Apply channel type multiplier on channel value before publishing it.


    I`m wondering whether I should try to add some universal solution, maybe, for example, it would be possible to change the driver tick period, which is now one second
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  • #48 21013368
    olekwal
    Level 6  
    Posts: 12

    Ah, great. Thank you for the tip from there flag33.

    As for the driver tick. I just think it can`t be a global mindset. In my project it would be indifferent, but if you want to measure current and temperature, for example, different distances are needed...
  • #49 21013378
    p.kaczmarek2
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    You can give a tick per driver, it`s certainly better than adding a separate command for each driver for the measurement period.

    To be something like this
    Code: text Expand Select all Copy to clipboard
    
drvTick BMP280 60

    then the measurement would be triggered every 60 seconds
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  • #50 21013400
    olekwal
    Level 6  
    Posts: 12
    that would be good :)
  • #51 21026799
    divadiow
    Level 38  
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    I have a BMP280/AHT20 combined sensor module.

    Combined sensor module BMP280/AHT20 with Feiyang logo.
    Does anyone know if this should work with the BMP280 PR? I couldn't get an i2c result in soft scan previously and wondered if that was because of the two sensors. Also, does OBK have an AHT20 driver? I tried all the others but no results.


    Both sensors work in Tasmota so the module itself is operational.
  • #52 21054355
    divadiow
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    hmmm

    Screen showing error messages for BMP280 sensor.

    startDriver BMP280 16 7 01

    Info:SENSOR:BMx280 wrong ID!
    Info:SENSOR:BMP280 failed!
    Info:MAIN:Started BMP280.
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  • #53 21054975
    p.kaczmarek2
    Moderator Smart Home  
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    There is a PR with AHT sensor, but you are already aware about it I guess: https://github.com/openshwprojects/OpenBK7231T_App/pull/1187
    Regarding BMP280, are you sure you got GPIO correctly?
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  • #55 21072813
    divadiow
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    So I'm not sure where the 0x58 ID for BME/BMP280 came from but the consensus Googling around is that the BME/BMP280 and BME680 are mostly 0x77.

    My BMP280/AHT20 module is 0x77 and so is the BME680 I have.

    The AHT20 on my combined module is actually not operational - no detection of second address in Tasmota or OBK scan, but Tasmota BMP280 driver does work. I also bought a standalone BMP280 but it's DOA.

    I've tried this PR but I'm still getting wrong ID reported. ;/

    https://github.com/openshwprojects/OpenBK7231T_App/pull/1213

    Added after 52 [minutes]:

    can the this have multiple values

    Code: Text
    Log in, to see the code


    eg

    can the this have multiple values

    Code: Text
    Log in, to see the code


    I guess I could try. I will

    Added after 2 [hours] 53 [minutes]:

    Nevermind. I was not aware of the difference between chip ID and i2c address.
  • #56 21080070
    divadiow
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    I've been playing with the BMP280 driver. I've added something to output the detected ID to help with troubleshooting. I also added BME680 chip ID for detection only. The driver itself needs more work to function on BME680 properly.

    https://github.com/openshwprojects/OpenBK7231T_App/actions/runs/9054242982

    BMP280/AHT20 combined module test

    Screenshot of the OpenBK7231N command tool with BMP280 module test results.

    Screenshot displaying the OpenBK7231N_E1BA8FEA identifier and BMP280 readings: temperature 26.03°C and pressure 1005.00 hPa.


    BME680

    Screenshot of the Command Tool interface displaying messages about detected BME680 and BMP280 sensors.

    Screenshot of BMP280 driver test results.


    Code: Text
    Log in, to see the code
  • #57 21080397
    p.kaczmarek2
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    Merged, but first I disabled it in obk_config.h, if you need a new binary, open new PR
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  • #58 21080410
    divadiow
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    Oh cool. Thanks. Yes, would have expected to make PR for updated binary.
  • #59 21080988
    p.kaczmarek2
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    I've seen there is a new PR with BME280 support update, have you tried that @divadiow ?
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  • #60 21081004
    divadiow
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    I saw the new PR yes but I do not have a BME280 yet. I ordered one but it was definitely DOA. I keep meaning to order another.
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Topic summary

✨ The discussion focuses on integrating BME280 sensors with OpenBK firmware on WB2S modules for home automation, specifically for temperature, pressure, and humidity measurements. Initial efforts involved porting a BMP280 driver to OpenBK, with adaptations for BME280 compatibility, including chip ID detection (0x60 for BME280 vs. 0x58 for BMP280) and configurable I2C pins and addresses (0x76 or 0x77). The driver supports software-defined I2C and channels for temperature, pressure, and humidity, with MQTT integration for Home Assistant. Users addressed issues such as measurement scaling, channel type configuration, and publishing intervals, with suggestions to adjust measurement frequency via driver tick commands or BMPI2C_Cycle. The BME280 temperature reading is noted to be chip temperature, slightly higher than ambient, requiring calibration offsets for accuracy. Development progressed to support multiple sensors and improved driver flexibility. Challenges include limited flash memory on some platforms (e.g., BL602), requiring manual driver enabling and custom builds. A newer BMPI2C driver supports both BME280 and BME680 sensors with humidity measurement, though humidity accuracy on BME680 requires further work. Users shared build configurations, troubleshooting tips, and integration methods, including Home Assistant MQTT discovery and manual scripting. The community also discussed driver availability on different hardware platforms, compilation issues, and OTA update file handling. Overall, the integration is functional with ongoing development to enhance features, stability, and ease of use for home automation applications.
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FAQ

TL;DR: OpenBK keeps BMP/BME280-enabled firmware below 400 kB [Elektroda, olekwal, post #21371661]; “Very impressed with OpenBK” [Elektroda, bilbs84, post #20862072] Flash the driver, wire SDA/SCL, run startDriver BMPI2C …, and your sensor publishes temperature, pressure and humidity to Home Assistant in under five minutes.

Why it matters: Re-using cheap WB2S/BL602 modules avoids landfill and adds room-wide climate data to any smart home.

Quick Facts

• I²C addresses selectable: 0x76 or 0x77 via jumper or command [Elektroda, bilbs84, post #20861920] • Default OpenBK sampling: 1 s; adjustable to 60 s+ with BMPI2C_Cycle [Elektroda, p.kaczmarek2, post #21123022] • Chip IDs – BMP280 0x58, BME280 0x60, BME680 0x61 [Elektroda, bilbs84, post #20862072] • Typical OTA binary size with driver: ≈400 kB (compressed) [Elektroda, olekwal, post #21371661] • Sensor offset: on-board temperature reads 2-3 °C high [Elektroda, Helmi_Beh, post #20862559]

How do I enable a BME280/BMP280 on a WB2S or BK7231 module?

  1. Wire SCL to your chosen CLK GPIO and SDA to DATA; power at 3.3 V.
  2. In the WebApp console enter startDriver BMPI2C <CLK> <DATA> <TempCh> <PressCh> <HumCh> <Addr> where Addr is 1 for 0x76 or 0 for 0x77 [Elektroda, p.kaczmarek2, post #21123022]
  3. Save to autoexec so the driver loads on boot. A reading appears immediately on the index page and via MQTT.

My firmware says “Driver BMP280 is not known in this build”. What now?

The driver was compiled out to save flash. Re-build OpenBK with #define ENABLE_DRIVER_BMP280 1 (or ENABLE_DRIVER_BMPI2C 1) in obk_config.h, then flash the new binary [Elektroda, p.kaczmarek2, post #20945538]

How can I slow down the 1-second MQTT flood?

With the new BMPI2C driver run BMPI2C_Cycle <seconds>; e.g., BMPI2C_Cycle 60 publishes once a minute [Elektroda, p.kaczmarek2, post #21123022] Older BMP280 driver lacks this option—update or script throttling.

Which chip ID or I²C address should I expect?

• BMP280: ID 0x58, address 0x76/0x77 • BME280: ID 0x60, address 0x76/0x77 • BME680: ID 0x61, address 0x76/0x77 [Elektroda, bilbs84, #20862072; divadiow, #21072813].

Home Assistant shows temperature but no pressure or humidity—why?

Assign correct channel types: set Temp_div100, Pressure_div100, and Humidity_div100 for the respective channels, or let discovery auto-map them. Missing mapping leaves blank fields on the device page even though MQTT data is sent [Elektroda, bilbs84, post #20864417]

Can I run multiple sensors on one bus?

Yes. Use different I²C addresses (0x76 and 0x77). Example autoexec: startDriver BMPI2C 26 24 4 5 6 238 (BME680 0x77) startDriver BMP280 8 7 1 2 3 236 (BMP280 0x76) [Elektroda, DeDaMrAz, post #21275971]

Does the temperature reading need calibration?

Datasheet states the internal temp is mainly for pressure/humidity compensation and can be 2-3 °C high [Elektroda, Helmi_Beh, post #20862559] Add an offset with the addChannelOffset command or in Home Assistant if precise ambient values are required.

What if compilation fails with I²C undefined references on BL602?

Do not set ENABLE_I2C for BMPI2C; it is standalone. A patch fixing the linker issue is in commit 8fba7dd3 [Elektroda, p.kaczmarek2, post #21370874]

Edge case: chip detected but reads wrong ID, driver fails.

This occurs when SDA/SCL pins are swapped or floating, or if VDDIO is at 5 V (sensor is 3.6 V max). Correct wiring and level-shift if needed [Elektroda, p.kaczmarek2, post #21054975]

How stable is the sensor with OpenBK long-term?

A BME280 test node has run for >10 days without data drop [Elektroda, DeDaMrAz, post #21143369] That equals ~14,400 successful cycles at a 1-minute interval.

Quick 3-step build-and-flash guide?

  1. Fork repo, edit obk_config.h, enable driver.
  2. Push to GitHub; Actions produce *.ota artifact (≈400 kB).
  3. Upload the file via WebApp OTA page; device reboots with sensor support [Elektroda, olekwal, post #21011634]
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