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BK7231N and CB3S: Detailed Guide on LoraTap SC400W-EU Switch Board Desoldering and Flashing

paulomac1000 6654 53

TL;DR

  • BK7231N-based LoraTap SC400W-EU curtain/blinds switch board was opened, identified, and prepared for flashing through the CB3S module.
  • Instead of desoldering the soldered board pins, the board was lifted, RX/TX were connected, power went to the outer pins, and flashing started by shorting GND to CEN.
  • Pin mapping used P6 WifiLED_n;0, P7 Btn;2, P8 LED_n;2, P9 Btn;1, P14 Rel;3, P23 Btn;3, P24 LED;3, and P26 Rel;1.
  • The flashing application could not read settings automatically, so all pins had to be found manually and entered into the configuration JSON.
  • A custom /autoexec.bat restored OPEN/CLOSE/STOP logic, with buttons auto-disabling after 60 seconds, reset lit for 1 second, and RESET toggling the buttons off.
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  • BK7231N and CB3S: Detailed Guide on LoraTap SC400W-EU Switch Board Desoldering and Flashing

    It is difficult to open the whole switch because the pins going to the board are not plugged in, but soldered. I wasn't able to desolder them. I lifted the board and soldered only RX and TX (according to the CB3S module documentation), and connected the power supply to the extreme pins on the board (see photo), where GND is on the left - the same as the OPEN button.

    VCC and GND:
    Electronic switch with connected wires and colored backlighting.

    RX and TX:
    Printed circuit board with attached wires on a white base.

    I started the flashing mode by shorting GND to CEN.

    The flashing application is not able to read the settings automatically. I had to find all the exits myself. Here they are:

    Code: text Expand Select all Copy to clipboard
    P6 (PWM0) "WifiLED_n;0"
P7 (PWM1) "Btn;2"
P8 (PWM2) "LED_n;2"
P9 (PWM3) "Btn;1"
P14 (N/A) "Rel;3"
P23 (ADC3) "Btn;3"
P24 (PWM4) "LED;3"
P26 (PWM5) "Rel;1"



    Here is the json that will make it easier to save the settings:

    Code: text Expand Select all Copy to clipboard
    {
  "vendor": "LoraTap",
  "bDetailed": "0",
  "name": "Full Device Name Here",
  "model": "SC400W-EU",
  "chip": "BK7231N",
  "board": "TODO",
  "flags": "0",
  "keywords": [
    "LoraTap",
    "SC400W-EU",
    "Curtains",
    "Blinds",
    "Switch",
    "Roller",
    "Shutters",
  ],
  "pins": {
    "6": "WifiLED_n;0",
    "7": "Btn;2",
    "8": "LED_n;2",
    "9": "Btn;1",
    "14": "Rel;3",
    "23": "Btn;3",
    "24": "LED;3",
    "26": "Rel;1"
  },
  "command": "",
  "image": "https://obrazki.elektroda.pl/8913814600_1698850663.webp",
  "wiki": "https://www.elektroda.com/rtvforum/viewtopic.php?p=20795168"
}


    It is also necessary to add a button management script to replicate the previous logic. I slightly improved it, i.e. the button deactivates itself after 60 and not 120 seconds, and the reset button lights up for one second instead of two, and the OPEN and CLOSE buttons can be turned off not only by pressing the RESET button, but by pressing it again.

    Add new file `/autoexec.bat`:

    Code: text Expand Select all Copy to clipboard
    // P26 - Relay 1 Close
// P7 - Btn 2 Stop
// P14 - Relay 3 Open
// P6 - Led backlight

// description
SetChannelLabel 1 Close
SetChannelLabel 2 Stop
SetChannelLabel 3 Open

// logic
alias Reset_Stop_Close backlog SetChannel 2 0; SetChannel 1 0
alias Reset_Stop_Open backlog SetChannel 2 0; SetChannel 3 0
alias Reset_Close_Open backlog SetChannel 1 0; SetChannel 3 0

addChangeHandler Channel1 == 1 Reset_Stop_Open
addChangeHandler Channel1 == 1 backlog startScript autoexec.bat resetCloseAfterMinute
addChangeHandler Channel2 == 1 Reset_Close_Open
addChangeHandler Channel2 == 1 backlog startScript autoexec.bat resetStopAfterSecond
addChangeHandler Channel3 == 1 Reset_Stop_Close
addChangeHandler Channel3 == 1 backlog startScript autoexec.bat resetOpenAfterMinute

// do not proceed
return

// Scripts

resetCloseAfterMinute:
// wait 60 seconds
delay_s 60
// stop opening
SetChannel 1 0
// done
return

resetStopAfterSecond:
// wait 1 second
delay_s 1
// disable button
SetChannel 2 0
// reset all scripts
stopAllScripts
// done
return

resetOpenAfterMinute:
// wait 60 seconds
delay_s 60
// stop opening
SetChannel 3 0
// done
return


    Enjoy!

    Cool? Ranking DIY
    About Author
    paulomac1000
    Level 2  
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    paulomac1000 wrote 2 posts with rating 3. Been with us since 2023 year.
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  • #2 20796868
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    Thank you, that's a very detailed guide. I've added this device to our teardowns list.
    Regarding shutters, I am planning to make dedicated driver for that soon, but I dont know when I will get enough free time for that.
    Helpful post? Buy me a coffee.
  • #3 20796938
    paulomac1000
    Level 2  
    Posts: 2
    Rate: 3

    It would be great to have roller blind controller logic that can be run on the cheapest buttons you can get for a few dollars at AliExpress Choice. For example, this LoraTap device costs about $17 at the brand store on AliExpress.
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  • #4 20977499
    hezipereg
    Level 7  
    Posts: 19
    Hi,
    Thank you for a detailed instructions. I've used these instructions and succeeded to operate the switch with my blinds.
    I was wondering if there is an option to control the switch LEDs. Currently, the open button is red and the rest are blue. Also, when I touch the buttons some of them turn blue and some red.
    To summarize, I want to have an option to control the touch buttons LED color.
    Thanks in advance,
  • #5 20977511
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
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    Rate: 12614
    It depends on how LEDs are connected.
    The template was mentioned in the first post:
    Code: text Expand Select all Copy to clipboard
    
P6 (PWM0) "WifiLED_n;0"
P7 (PWM1) "Btn;2"
P8 (PWM2) "LED_n;2"
P9 (PWM3) "Btn;1"
P14 (N/A) "Rel;3"
P23 (ADC3) "Btn;3"
P24 (PWM4) "LED;3"
P26 (PWM5) "Rel;1"

    This indicates that currently P24 is a LED on channel 3. You can change it to LED_n to invert the LED state. You can also swap the channels between, for example, P8 and P24.

    You can also change the WiFiLED to LED, if it suits you.

    The limiting factor is the hardware, it all depends on how the LEDs are connected on the PCB.

    Or maybe is there more LEDs on the device PCB than it's indicated in our template?
    Helpful post? Buy me a coffee.
  • #6 20977517
    hezipereg
    Level 7  
    Posts: 19
    Thanks for your reply.
    I actually don't know the difference between all these LEDs types that you mentioned (LED, LED_n, and WifiLED_n).
    Where can I read what it means?
    My LoraTap switch has 3 touch buttons and thus I think there are three LEDs.
    Anyway, what should happen if I change from LED_n to LED or from WifiLED_n to LED, etc? How changing them will get me to the point that I can change the color?
    Regards,
  • #7 20977537
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    IO docs:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/ioRoles.md
    LED is on when linked channel is on, LED_n has inverted state (it's on when channel is off), WiFILED shows WiFi state, WIFILED_n is inverted WifiLED.

    Those roles are GPIO roles, they are per single GPIO. It's not possible to change color with that due to the hardware limitations. You can only send high or low state.

    That is, unless, they are two LEDs on the pin... then, it's very possible that you can switch the colors (reverse them) by changing LED to LED_n or vice versa.

    It's relatively hard for me to be more specific because I don't know the hardware you're operating on. How are LEDs connected?

    Maybe you can backup your configuration, open OBK web app, go to GPIO Doctor and play around there.
    Helpful post? Buy me a coffee.
  • #8 20978313
    hezipereg
    Level 7  
    Posts: 19
    I managed to switch the LED color by playing with it in GPIO finder.
    The correct configuration for me is:
    Code: text Expand Select all Copy to clipboard
    "pins": {
    "6": "Rel_n;0",
    "7": "Btn;2",
    "8": "LED_n;2",
    "9": "Btn;1",
    "14": "Rel;3",
    "23": "Btn;3",
    "24": "LED_n;3",
    "26": "Rel;1"
  },

    Additionally, changing "6": "WifiLED_n;0" to "6": "Rel_n;0" allowed me to add a button which turn on/off the LEDs. This can be used for example to turn off the LEDs during day time when the sun is up.
  • #9 20983870
    hezipereg
    Level 7  
    Posts: 19
    I have noticed that the switch supports running time parameter which configures how much time the switch will be opened/closed. I understand that we can imitate this field using the autoexec.bat file but I want to have something that can be controlled from home assistant.
    Who can guide me how to find this field and add it to home assistant. I managed to add input_number to home assistant and use it but I want to be able to control the value through openbeken.
    Thanks in advance for any help provided!
    Blind running time settings with a mobile app
  • #10 20987941
    hezipereg
    Level 7  
    Posts: 19
    Any help would be appreciated!!!
  • #11 20987981
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    Which channel stores this value in autoexec.bat ? You can set any channel via MQTT with set topic:
    BK7231N and CB3S: Detailed Guide on LoraTap SC400W-EU Switch Board Desoldering and Flashing
    Helpful post? Buy me a coffee.
  • #12 20988171
    hezipereg
    Level 7  
    Posts: 19
    Hi,
    The autoexec.bat does not contain channel which stores the value. This is the autoexec.bat:
    Code: text Expand Select all Copy to clipboard
    
// P26 - Relay 1 Close
// P7 - Btn 2 Stop
// P14 - Relay 3 Open
// P6 - Led backlight

// description
SetChannelLabel 1 Close
SetChannelLabel 2 Stop
SetChannelLabel 3 Open

// logic
alias Reset_Stop_Close backlog SetChannel 2 0; SetChannel 1 0
alias Reset_Stop_Open backlog SetChannel 2 0; SetChannel 3 0
alias Reset_Close_Open backlog SetChannel 1 0; SetChannel 3 0

addChangeHandler Channel1 == 1 Reset_Stop_Open
addChangeHandler Channel1 == 1 backlog startScript autoexec.bat resetCloseAfterMinute
addChangeHandler Channel2 == 1 Reset_Close_Open
addChangeHandler Channel2 == 1 backlog startScript autoexec.bat resetStopAfterSecond
addChangeHandler Channel3 == 1 Reset_Stop_Close
addChangeHandler Channel3 == 1 backlog startScript autoexec.bat resetOpenAfterMinute

// do not proceed
return

// Scripts

resetCloseAfterMinute:
// wait 60 seconds
delay_s 60
// stop opening
SetChannel 1 0
// done
return

resetStopAfterSecond:
// wait 1 second
delay_s 1
// disable button
SetChannel 2 0
// reset all scripts
stopAllScripts
// done
return

resetOpenAfterMinute:
// wait 60 seconds
delay_s 60
// stop opening
SetChannel 3 0
// done
return


    I am actually new with OpenBeken. If there is somewhere I can read and learn how to do it let me know.
    I don't really know how to define this channel, how to link it to TuyaMCU or should I do everything in the autoexec.bat without linking to Tuya?

    Thanks in advance,
  • #13 20988420
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    So, to which delay from this script are you referring to? Are you referring to this one minute delay:
    Code: text Expand Select all Copy to clipboard
    
// wait 60 seconds
delay_s 60

    The following delay appears twice in the code.
    If that's the delay you want to change then yes, we can try to modify the script so the delay is accessible from the Home Assistant. Just please confim whether it's the thing you want to change.

    Here you can find some more sample scripts:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/autoexecExamples.md
    Helpful post? Buy me a coffee.
  • #14 20988447
    hezipereg
    Level 7  
    Posts: 19
    Yes this is the delay I was referring to.
    The desired solution is to have and `input_number` in home assistant that will control this value. When the user changes the `input_number` in home assistant it will change the value in the autoexec.bat script.
    Another thing, before changing the FW to OpenBeken, Tuya provided an interface to this field. Is there a way to do it through Tuya using dpId or the only way is to bypass it with the autoexec.bat. If I can do it through Tuya, how can I find the correct dpId?
  • #15 20988466
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    If you want to have this as an input number, then you need to do the following.
    1. change all:
    Code: text Expand Select all Copy to clipboard
    
// wait 60 seconds
delay_s 60

    to
    Code: text Expand Select all Copy to clipboard
    
// wait $CH4 seconds
delay_s $CH4

    so it uses value of channel 4
    2. Then, add at the top of the script:
    Code: text Expand Select all Copy to clipboard
    

// description
SetChannelLabel 1 Close
SetChannelLabel 2 Stop
SetChannelLabel 3 Open
// NEW
// set label of timer value
SetChannelLabel 4 Delay
// set type of timer value
SetChannelType 4 TextField
// set to remember last state
setStartValue 4 -1
// set default value if needed
if $CH4==0 then setChannel 4 60

    3. Save autoexec.bat and reboot

    The following should add a text field with default value 60 on the main panel. Check if it works and if you can change that value 60 in the field, as I may have made a typo in the script, etc. Then check if changing this value works for you. Later we can try to link it to Home Assistant.
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  • #16 20988845
    hezipereg
    Level 7  
    Posts: 19
    This worked!!!
    I linked this field to home assistant using automation on any change to an input number I defined which eventually calls MQTT publish with the input number value. This works perfectly.
    Here is the update autoexec.bat for anyone who is interested to use:
    Code: text Expand Select all Copy to clipboard
    // P26 - Relay 1 Close
// P7 - Btn 2 Stop
// P14 - Relay 3 Open
// P6 - Led backlight

// description
SetChannelLabel 1 Close
SetChannelLabel 2 Stop
SetChannelLabel 3 Open

// set label of timer value
SetChannelLabel 4 "Open/Close Duration"
// set type of timer value
SetChannelType 4 TextField
// set to remember last state
setStartValue 4 -1
// set default value if needed

if $CH4==0 then setChannel 4 30

// logic
alias Reset_Stop_Close backlog SetChannel 2 0; SetChannel 1 0
alias Reset_Stop_Open backlog SetChannel 2 0; SetChannel 3 0
alias Reset_Close_Open backlog SetChannel 1 0; SetChannel 3 0

addChangeHandler Channel1 == 1 Reset_Stop_Open
addChangeHandler Channel1 == 1 backlog startScript autoexec.bat resetCloseAfterDelay
addChangeHandler Channel2 == 1 Reset_Close_Open
addChangeHandler Channel2 == 1 backlog startScript autoexec.bat resetStopAfterSecond
addChangeHandler Channel3 == 1 Reset_Stop_Close
addChangeHandler Channel3 == 1 backlog startScript autoexec.bat resetOpenAfterDelay

// do not proceed
return

// Scripts

resetCloseAfterDelay:
// wait $CH4 seconds
delay_s $CH4
// stop opening
SetChannel 1 0
// done
return

resetStopAfterSecond:
// wait 1 second
delay_s 1
// disable button
SetChannel 1 0
SetChannel 2 0
SetChannel 3 0
// reset all scripts
stopAllScripts
// done
return

resetOpenAfterDelay:
// wait $CH4 seconds
delay_s $CH4
// stop opening
SetChannel 3 0
// done
return

    Another thing, I have a relay that controls the switch LEDs. How can I define the name for this relay?
    In the autoexec.bat I see the usage of:
    Code: text Expand Select all Copy to clipboard
    // description
SetChannelLabel 1 Close
SetChannelLabel 2 Stop
SetChannelLabel 3 Open

    I don't understand how the channel definition is linked to the actual relay. Currently the relay I've added is listed as "toggle 0" and I want to change it to be light or something like that.
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  • #17 20988880
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    Well, the LEDs are defined in the "Configure module" tab and there is a field to enter a linked channel number, see an example below:
    Configuration of BK7231T_WB3S module pins with assigned channels and roles for each pin.
    What do you want to do with that LED? Is your LED on P6?

    If you set a channel, let's say, channel 5 for P6, and set LED role for P6, then you will be able to control this LED manually via channel 5.

    If you want then to manually toggle channel 5 (the one that has linked LED now), you can write in script:
    Code: text Expand Select all Copy to clipboard
    
toggleChannel 5

    or
    Code: text Expand Select all Copy to clipboard
    
setChannel 5

    The following line will toggle channel 5 and all LEDs and RELs (and LED_n, and REL_n) on this channel will follow.

    Alternatively, you can set P6 (your LED) role to WIFILED_n, then it will automatically without channel and display your WiFi state.
    Helpful post? Buy me a coffee.
  • #18 20988984
    hezipereg
    Level 7  
    Posts: 19
    Yes the LED is on P6.
    OK now I understand how to set a channel. I managed as you showed me to add channel for the LED and called it light. Now I have a button in Home Assistant to toggle the switch LEDs. Setting P6 as Rel_n is the way the toggle button was added.
    I didn't understand what you said regarding
    Quote:
    Alternatively, you can set P6 (your LED) role to WIFILED_n, then it will automatically without channel and display your WiFi state.
    In that case, how will I be able to turn on/off the LEDs?
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  • #19 20988997
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    There are two ways to control LEDs.
    - first way is to assign a LED (or a LED_n, which is inversed LED) role and a channel, then LED will follow the channel and will be scriptable and controllable by user
    - the second way is to assign a WiFiLED role, which will make LED display the WiFi state (fast blinking when connecting, etc, etc, on when connected, etc)

    You can read more about IO roles here:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/ioRoles.md
    Table describing the states of LED WiFi and LED WiFi_n.

    hezipereg wrote:

    I didn't understand what you said regarding
    Quote:
    Alternatively, you can set P6 (your LED) role to WIFILED_n, then it will automatically without channel and display your WiFi state.
    In that case, how will I be able to turn on/off the LEDs?

    WIFI_LED is not controllable by user, it just displays the state of your WiFi connection. If you want to be able to manually control the LED, then choose LED (or LED_n) state.

    Some Tuya devices have two onboard LEDs and in their case users choose to configure first LED as WiFiLED_n to display WiFi state and to configure second LED as LED on the same channel which Relay is using to display the relay state.
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  • #20 20989113
    hezipereg
    Level 7  
    Posts: 19
    That worked (setting it as LED_n), assigning a channel and adding the channel to the autoexec.bat script.
    The perfect solution for me is to have both the wifi indication and to be able to control it.
    Quote:
    Some Tuya devices have two onboard LEDs and in their case users choose to configure first LED as WiFiLED_n to display WiFi state and to configure second LED as LED on the same channel which Relay is using to display the relay state.

    How do I know if this is the case here?

    Additionally, some of these switches have a slider to control open/close by percentage:
    App interface showing sliders with a hand icon
    Is it possible to do this logic?
  • #21 20989611
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    hezipereg wrote:

    Quote:
    Some Tuya devices have two onboard LEDs and in their case users choose to configure first LED as WiFiLED_n to display WiFi state and to configure second LED as LED on the same channel which Relay is using to display the relay state.

    How do I know if this is the case here?

    Was there two LEDs blinking before you flashed device?
    When you open device case, are there multiple LEDs?
    When doing Tuya Config extraction:
    https://www.youtube.com/watch?v=WunlqIMAdgw&ab_channel=Elektrodacom
    are there multiple LEDs found?
    If you use GPIO Doctor from the Web App, are you able to find multiple GPIOs with LEDs?

    hezipereg wrote:

    Additionally, some of these switches have a slider to control open/close by percentage:
    App interface showing sliders with a hand icon
    Is it possible to do this logic?

    It's certainly possible to do that and I think I may have already seen as user-made script for that on our forum, but I am not sure where it was. This requires some changes to autoexec.bat. You need to have some basic programming knowledge for that. We may try to do something like that but I don't have shutters at home so you'll have to be the one testing.
    Helpful post? Buy me a coffee.
  • #22 20989757
    hezipereg
    Level 7  
    Posts: 19
    Quote:
    Was there two LEDs blinking before you flashed device?
    When you open device case, are there multiple LEDs?
    When doing Tuya Config extraction:
    https://www.youtube.com/watch?v=WunlqIMAdgw&ab_channel=Elektrodacom
    are there multiple LEDs found?
    If you use GPIO Doctor from the Web App, are you able to find multiple GPIOs with LEDs?

    I don't remember how many LEDs were blinking. I will try to do the Tuya configuration extraction later tonight and will update accordingly.

    Quote:
    It's certainly possible to do that and I think I may have already seen as user-made script for that on our forum, but I am not sure where it was. This requires some changes to autoexec.bat. You need to have some basic programming knowledge for that. We may try to do something like that but I don't have shutters at home so you'll have to be the one testing.

    I have programming skills. I am a programmer mainly for embedded systems using C, python, etc.. I am up for the challenge. No problem, I will debug it myself. Thanks!
  • #23 20989828
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
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    Rate: 12614
    Ok, so if you want to have a slider, let's start with determining which variable we need to change.

    If I understand correctly, you want to make this delay:
    Code: text Expand Select all Copy to clipboard
    
resetCloseAfterDelay:
// wait $CH4 seconds
delay_s $CH4
// stop opening
SetChannel 1 0
// done
return

    configurable with a slider?

    Or, actually, it doesn't look like it. It seems that we need to introduce a separate variable to store how much the shutter is open.... because channel 4 is a time required to fully open or close the shutter.

    So maybe we can introduce a separate channel, let's say with a type of Slider (that has range 0-100) and then normalize it to 0-1 range and multiply the open/close time by that? Of course, that's not the full logic.
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  • #24 20990076
    hezipereg
    Level 7  
    Posts: 19
    I know the logic, I don't know how to implement it in OpenBeken.
    The logic (pseudo code) should be as follows:
    1. define an input number which holds the time it takes for the shutter to open/close - `fully_open_close_duration`.
    2. define an input number which holds the number of seconds left for the shutter to open/close - ` open_duration_left`.
    3. define a shutter position (slider) which we could calibrate manually for example to fully open or fully close somehow. This calibration should also change ` open_duration_left`. For example if we calibrate to fully close then ` open_duration_left` = `fully_open_close_duration`
    4. once an open/close operation occurs, count the number of seconds. This should take into account if stop button was pressed - `last_operation_duration`
    5. If the operation was open then ` open_duration_left` -= `last_operation_duration` else if close ` open_duration_left` += `last_operation_duration`.
    6. set the shutter position according to the following : ((` open_duration_left` / `fully_open_close_duration`) * 100).

    Now if you use the slider to open/close:
    1. Get slider position change. We can save `previous_shutter_position` and `current_shutter_position`.
    2. Calculate the number of seconds the shutter should be open close by the change (`previous_shutter_position` - `current_shutter_position`). For example if the change is from 60% open to 70% open then the shutter should be opened for 10% * `fully_open_close_duration` seconds.
    3. change ` open_duration_left` accordingly.

    Something like that.
  • #25 20990079
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    Before we consider the scripting approach, maybe it would be worth looking into the C code itself?

    Here are our drivers:
    https://github.com/openshwprojects/OpenBK7231T_App/tree/main/src/driver
    Here is a sample driver:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/driver/drv_chargingLimit.c
    Here is another one:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/driver/drv_pwmToggler.c

    Maybe it would be easier to just make a dedicated driver for shutters? I can help, it's just that I don't have shutters. Do you know C?
    Helpful post? Buy me a coffee.
  • #26 20990145
    hezipereg
    Level 7  
    Posts: 19
    Sure I know C.
    Let's try to do the driver.
  • #27 20990148
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    Ok, so first you need to add an entry to drivers table here:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/driver/drv_main.c
    Here is a structure of a driver:
    Code: C / C++
    Log in, to see the code

    Name your driver "shutters" and then you can create a separate file called drv_shutters.c and add the stub functions there.

    The functions itself should be self-explanatory but when in doubt you can just peek into other drivers, for example here is a bridge relay driver:
    https://github.com/openshwprojects/OpenBK7231T_App/blob/main/src/driver/drv_bridge_driver.c

    Do you know Git? If you open that in a draft pull request, I can monitor your activity and give more detailed hints.
    Helpful post? Buy me a coffee.
  • #28 20990212
    hezipereg
    Level 7  
    Posts: 19
    I know GIT. I work with GitLab which is quite similar to GitHub.
    In order to open a draft pull request, I need to first open a new branch right or an issue and then pull request from that issue?

    Added after 1 [hours] 4 [minutes]:

    In the meantime I've added the following
    drv_main.c:
    Code: C / C++
    Log in, to see the code


    drv_shutter.c
    Code: C / C++
    Log in, to see the code


    The VS project does not compile?
  • #29 20990344
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14599
    Help: 654
    Rate: 12614
    You need to create a branch. Issues are irrevelant for creating PR.

    The VS project is for Windows Simulator, which I use to quickly debug things. It allows you to run virtual OBK device on Windows:
    OpenBeken simulator diagram with electronic circuit on a grid.

    To compile BK7231 build, you need to either:
    1. use online github builds:
    https://www.elektroda.com/rtvforum/topic4033833.html
    2. checkout SDK, either T or N:
    https://github.com/openshwprojects/OpenBK7231T
    https://github.com/openshwprojects/OpenBK7231N
    checkout app to the SDK:
    https://github.com/openshwprojects/OpenBK7231T_App
    so your path is:
    C:/Anything/GIT/OpenBK7231T/apps/OpenBK7231T_App
    run build in cygwin
    Screenshot of script compilation in Cygwin terminal for the BK7231T platform.
    Helpful post? Buy me a coffee.
  • #30 20990439
    hezipereg
    Level 7  
    Posts: 19
    Quote:
    You need to create a branch. Issues are irrevelant for creating PR.

    I don't have the open branch button available.

    Quote:
    run build in cygwin

    I tried to build using wsl. I get: ./b.sh: 1: ./build_app.sh: not found

    I tried calling ./build_app.sh apps/OpenBK7231T_App OpenBK7231T_App 1.0.0 and got ./build_app.sh: bad interpreter: /bin/sh^M: no such file or directory
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Topic summary

✨ The discussion centers on the BK7231N-based LoraTap SC400W-EU switch board, focusing on desoldering challenges, flashing procedures, and firmware customization using OpenBeken. Initial difficulties in desoldering the switch pins led to partial soldering of RX, TX, VCC, and GND for flashing via shorting GND to CEN. Users shared detailed GPIO pin mappings for LEDs, buttons, and relays, clarifying LED roles such as LED, LED_n (inverted), and WifiLED_n, with hardware limitations restricting color control to on/off states. Configuration adjustments via the autoexec.bat script enabled control of LED states and introduced a runtime parameter for shutter open/close duration, which was integrated with Home Assistant through MQTT and input_number entities. Advanced users discussed developing a dedicated shutter driver in C within the OpenBK7231T_App framework, including driver structure, function callbacks, and build environment setup using Cygwin or WSL. Troubleshooting build issues and GitHub workflow for pull requests were addressed. The conversation also covered TuyaMCU device considerations, flashing tools, and extracting Tuya configurations. Finally, a user shared a custom blind driver script for the LoraTap SC400W-EU, emphasizing unique pin assignments and MQTT integration for Home Assistant control, highlighting the variability of hardware revisions.
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FAQ

TL;DR: With 8 mapped GPIOs and one simple script, you can flash a BK7231N/CB3S-based LoraTap SC400W-EU without fully desoldering the board; as one expert reply put it, "We have a new working native driver for shutters" if you want a cleaner alternative later. This FAQ helps OpenBeken users wire, flash, script, and tune shutter control. [#21856035]

Why it matters: This thread turns a hard-to-open Tuya curtain switch into a documented OpenBeken workflow, including pin mapping, LED behavior, MQTT control, and the path from script hacks to native shutter support.

Approach What it does Main advantage Main limit
autoexec.bat script Recreates Open/Stop/Close logic and timers Works now on SC400W-EU Percentage control is manual to design
GPIO remapping Changes LED behavior and adds LED toggle control Fast hardware-aware customization Cannot create colors the PCB cannot drive
Native shutter driver Adds dedicated shutter logic Better fit for 0–100% control Arrived later and needs testing per device

Key insight: Start with the proven SC400W-EU pin template and autoexec.bat, then move to the native shutter driver only if you need cleaner percentage-based control. The hardware wiring, especially LED and UART layout, decides what is possible. [#20795168]

Quick Facts

  • The working SC400W-EU OpenBeken template maps 8 pins: P6, P7, P8, P9, P14, P23, P24, and P26 for WiFi LED, buttons, LEDs, and relays. [#20795168]
  • The original script improved factory-like timing by changing auto-off from 120 s to 60 s and the reset indicator from 2 s to 1 s. [#20795168]
  • A later Home Assistant-friendly version exposes channel 4 as "Open/Close Duration" with a default of 30 s instead of the earlier 60 s example. [#20988845]
  • One user reported the LoraTap unit cost about $17 from the brand store on AliExpress, showing this is a low-cost shutter platform. [#20796938]
  • WSL builds succeeded after installing lib32z1 and python-is-python3; Cygwin also worked, while WSL initially failed for another participant. [#20994640]

How do I open and flash a LoraTap SC400W-EU with a BK7231N/CB3S module when the board pins are soldered and hard to desolder?

Open it by lifting the board instead of fully removing the soldered pin header. Then solder only RX and TX directly to the CB3S pads, and feed power to the two extreme board pins where GND is on the left, the same side as the OPEN button. To enter flashing mode, short GND to CEN. This avoids desoldering the whole switch assembly and was reported to work on the SC400W-EU with a BK7231N-based CB3S module. [#20795168]

Which RX, TX, VCC, GND, and CEN connections are needed to put the CB3S module on a LoraTap SC400W-EU into flashing mode?

You need RX and TX on the CB3S module pads, VCC and GND on the two extreme board pins, and a temporary short from GND to CEN to enter flashing mode. The thread states GND is on the left side, matching the OPEN button side. The author powered the board from those outer pins and did not rely on automatic pin detection in the flashing app. That manual wiring was enough to flash the device successfully. [#20795168]

What is the correct OpenBeken pin template for the LoraTap SC400W-EU, including the button, relay, and LED mappings?

The working template is: P6 WifiLED_n;0, P7 Btn;2, P8 LED_n;2, P9 Btn;1, P14 Rel;3, P23 Btn;3, P24 LED;3, and P26 Rel;1. That maps three buttons, two relay outputs, and indicator LEDs for the SC400W-EU. A later LED-focused variant changed P6 to Rel_n;0 and P24 to LED_n;3, but the first published template is the baseline mapping for flashing and initial setup. [#20795168]

How can I use autoexec.bat in OpenBeken to recreate the original LoraTap shutter logic with Open, Close, Stop, and auto-reset timers?

Use autoexec.bat to label channels 1, 2, and 3 as Close, Stop, and Open, then add change handlers that cancel opposite actions and start timed reset scripts. 1. Create aliases such as Reset_Stop_Open and Reset_Close_Open. 2. Attach addChangeHandler rules so Channel1 and Channel3 auto-start timer scripts. 3. Use delay_s 60 for open and close, and delay_s 1 for stop reset. This reproduces the switch logic and prevents both directions staying active together. [#20795168]

What is the difference between LED, LED_n, WifiLED, and WifiLED_n in OpenBeken IO roles?

LED follows a linked channel, while LED_n follows the same channel with inverted logic. WifiLED shows Wi-Fi state, and WifiLED_n shows the same status with inverted polarity. "IO role" is a per-GPIO function assignment that tells OpenBeken what a pin should do and whether its logic is normal or inverted. The thread also notes these roles only drive high or low states, so they do not create arbitrary colors unless the PCB already supports multiple LED paths. [#20977537]

How can I change the touch button LED behavior or color indication on a LoraTap SC400W-EU by remapping GPIO roles in OpenBeken?

Change the LED-related pin roles and linked channels, then test in GPIO Doctor. One user switched to this working LED setup: P6 Rel_n;0, P8 LED_n;2, and P24 LED_n;3. That reversed the visible color behavior on the touch buttons and made the front-panel indication match the desired state better. The key limit is hardware: if the PCB exposes only one LED path per button, remapping can invert or swap behavior, but not invent a new color. [#20978313]

Why does changing P6 from WifiLED_n to Rel_n on the SC400W-EU let me add a separate button to turn the switch LEDs on and off?

Because Rel_n binds P6 to a normal user channel instead of automatic Wi-Fi status logic. With WifiLED_n, OpenBeken controls that pin from connection state and you cannot toggle it manually. After changing P6 to Rel_n;0, one user added a dedicated channel and exposed it in Home Assistant as a separate LED on/off control. That turned the front LEDs into a scriptable output instead of a fixed network indicator. [#20978313]

How do I expose the shutter open/close duration as a configurable field in OpenBeken and control it from Home Assistant over MQTT?

Move the fixed delay into channel 4 and use delay_s $CH4 instead of delay_s 60. Then set SetChannelLabel 4 "Open/Close Duration", SetChannelType 4 TextField, setStartValue 4 -1, and a default like if $CH4==0 then setChannel 4 30. A user confirmed this worked and then pushed new values from a Home Assistant input_number through MQTT publish automation. That made the duration adjustable without editing the script again. [#20988845]

Where can I read about OpenBeken scripting, GPIO roles, and example autoexec.bat files for shutters and similar devices?

Read the links shared in the thread to the OpenBK7231T_App documentation. The GPIO role reference was linked under docs/ioRoles.md, and script examples were linked under docs/autoexecExamples.md. The discussion explicitly points new users to those two files when explaining LED, LED_n, WifiLED_n, channel logic, and timed scripts. Those references are the thread’s main documentation path for OpenBeken scripting and pin-role behavior. [#20988420]

What is TuyaMCU, and how does it affect flashing and configuring a curtain switch that has a separate MCU connected over UART?

TuyaMCU is a secondary microcontroller that handles device features and talks to the Wi-Fi module over UART using dpIDs and commands. If RX and TX from the Wi-Fi module are wired to that MCU, the switch is a TuyaMCU design and configuration changes differ from a simple GPIO-only device. In that case, flashing OpenBeken is still possible, but you must also identify the UART relationship and often configure TuyaMCU-specific behavior instead of only mapping pins. [#21109644]

How do I find the correct Tuya dpId for a curtain switch parameter like running time if I want to preserve Tuya-style control instead of replacing it with autoexec.bat logic?

First confirm the switch actually uses TuyaMCU, then inspect TuyaMCU traffic or use the dedicated TuyaMCU guide linked in the thread. The discussion never identifies a confirmed dpId for the running-time field on this SC400W-EU, so the practical answer in-thread was to replace that feature with channel-based autoexec.bat logic. This is an important edge case: if you cannot see or decode the UART parameter, you cannot preserve the Tuya control field reliably. [#21109644]

What is GPIO Doctor in the OpenBeken web app, and how can it help identify LEDs, buttons, and relays on a LoraTap switch?

GPIO Doctor is an OpenBeken web-app tool for probing GPIO behavior and testing pin roles interactively. The thread recommends it to discover whether more LEDs exist than the template shows and to experiment safely with LED inversions and channel links. One user used the GPIO finder workflow to reach a working LED configuration for P6, P8, and P24. It is especially useful when the PCB differs from the published SC400W-EU mapping. [#20978313]

OpenBeken autoexec script vs a native shutter driver — which approach is better for percentage-based blind control on LoraTap switches?

Use autoexec.bat for immediate results, but prefer the native shutter driver for cleaner 0–100% control. The thread shows scripts work well for Open, Close, Stop, timers, and MQTT-exposed duration fields, but percentage logic quickly becomes complex. Later, the maintainer stated, “We have a new working native driver for shutters,” which makes the driver path the better long-term choice when your firmware supports it. For quick deployment, script first; for maintainability, move to the driver. [#21856035]

How can I implement or test percentage slider control for shutters in OpenBeken so Home Assistant can set the blind position from 0 to 100%?

Implement it by separating full-travel time from current position. The thread’s proposed logic uses one channel for full open/close duration, another for current or saved position, and a Slider-type channel with a 0–100 range as the target. Then the script normalizes the requested change and runs open or close long enough to move that percentage. A later shared script used channels 9, 10, and 11 for saved, current, and target position, plus channels 20–22 for Down, Stop, and Up controls. [#21484624]

What causes OpenBK7231T_App builds to fail under WSL, and how do lib32z1, python-is-python3, line endings, Cygwin, and Docker compare as build options?

WSL failed for two concrete reasons in the thread: missing lib32z1 and missing python-is-python3. One user also hit /bin/sh^M: no such file or directory, which points to Windows CRLF line endings. After installing both packages, the WSL build succeeded. Another participant reported WSL still failed on their side and recommended Cygwin as the proven option, while also noting an alternative Docker build system existed in the repository. This makes Cygwin the known-good path and WSL workable after fixes. [#20994640]
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