[BK7231N/CBU] Door sensor without TuyaMCU - how to connect to UART RX/TX

Question

Hi there, first and most important: thank you VERY MUCH for all your work you did! :) Then I have a question concerning this TUYA door and window sensor. It comes with a BK7231N (pic1) soldered onto a board like this (pic2). Now, as you can see, I can't easily access the backside with RX and TX...

p.kaczmarek2 · Answer

Hello, I will try to help you... hmm... why do you think this device is problematic?
It's not WB2L/WB2L_M1/CB2L.. it's CBU. It's very easy to flash.

Pin number	Symbol	I/O type	Function
1	P14	I/O	Common GPIO, which can be reused as SPI_SCK (Correspond to Pin 11 of the IC)
2	P16	I/O	Common GPIO, which can be reused as SPI_MOSI (Correspond to Pin 12 of the IC)
3	P20	I/O	Common GPIO (Correspond to Pin 20 of the IC)
4	P22	I/O	Common GPIO (Correspond to Pin 18 of the IC)
5	ADC	I/O	ADC, which corresponds to P23 on the internal IC (Correspond to Pin 17 of the IC)
6	RX2	I/O	UART_RX2, which corresponds to P1 on the internal IC. (Correspond to Pin 28 of the IC)
7	TX2	I/O	UART_TX2, which is used for outputting logs and corresponds to P0 of the internal IC (Correspond to Pin 29 of the IC)
8	P8	I/O	Support hardware PWM (Correspond to Pin 24 of the IC)
9	P7	I/O	Support hardware PWM (Correspond to Pin 23 of the IC)
10	P6	I/O	Support hardware PWM (Correspond to Pin 22 of the IC)
11	P26	I/O	Support hardware PWM (Correspond to Pin 15 of the IC)
12	P24	I/O	Support hardware PWM (Correspond to Pin 16 of the IC)
13	GND	P	Power supply reference ground
14	3V3	P	Power supply 3V3
15	TX1	I/O	UART_TX1, which is used for transmitting user data and corresponds to Pin 27 of the IC. For the MCU solution, please refer to CBx Module.
16	RX1	I/O	UART_RX1, which is used for receiving user data and corresponds to Pin 26 of the IC. For the MCU solution, please refer to CBx Module.
17	P28	I/O	Common GPIO (Correspond to Pin 10 of the IC)
18	CEN	I/O	Reset pin, low active (internally pulled high), compatible with other modules (Correspond to Pin 21 of the IC)
19	P9	I/O	Common GPIO (Correspond to Pin 25 of the IC)
20	P17	I/O	Common GPIO, which can be reused as SPI_MISO (Correspond to Pin 14 of the IC)
21	P15	I/O	Common GPIO, which can be reused as SPI_CS (Correspond to Pin 13 of the IC)
Test point	CSN	I/O	Mode selection pin. If it is connected to the ground before being powered on, enter the firmware test mode. If it is not connected or connected to VCC before being powered on, enter the firmware application mode. Correspond to Pin 19 on the internal IC.

As you can see, TX1 and RX1 are easily accessible.

By the way, please check where the mentioned pads for goldpins connect, and post information here. It might be useful for some people, but I'd already try guessing that R stands for RX and T for TX. Then G is Ground, V is Voltage...

Then you can most likely configure it like here:
Door/window sensor without TuyaMCU - deep sleep and energy saving, OpenBeken

Btw, if you are flashing them, please also provide us a 2MB Tuya firmware backup from them

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.

gramais · Answer

WOW - Thank you!That was really a super fast answer. I now would flash via python following this GitHub guide: this command read out the original TUYA FW from the device?Code: text Expand Select all Copy to clipboardpython uartprogram firmware.bin -d com4 -r

p.kaczmarek2 · Answer

Your command is not correct. It lacks unprotect and read size. Please watch our video to get the correct hid_download_py commands for flashing: If you want something simpler, here is new flasher (but I had few reports about issues with it): Here is hid_download_py (old flasher):

gramais · Answer

Okay,

thanks again. I ran

python3 uartprogram firmware_backup.bin -d tty.usbserial-1410 -r -s 0x0 -l 0x200000

Sadly quits with:

ImportError: cannot import name 'Timeout' from 'serial' (/Users/username/Library/Python/3.9/lib/python/site-packages/serial/__init__.py)

Although this file exists and contains:


"""
`serial` is an object serialization/deserialization library intended to facilitate authoring of API models which are
readable and introspective, and to expedite code and data validation and testing. `serial` supports JSON, YAML, and
XML.
"""

from __future__ import nested_scopes, generators, division, absolute_import, with_statement, 
   print_function, unicode_literals

from . import utilities, abc, model, marshal, errors, properties, meta, hooks, test, request
~                                                                                                                                                                                                                          
~                                                                                                                                                                                                                          
~

Any idea: should I add a line to this file?

p.kaczmarek2 · Answer

Can you try Windows tool first?

gramais · Answer

The BACKUP: Got it working using a lower baud rate: Code: text Expand Select all Copy to clipboardpython3 uartprogram firmware_backup.bin -d /dev/tty.usbserial-1410 -r -s 0x0 -l 0x200000 -b 115200 Worked with these rates 115200, 230400 and 460800 (max.). At least I hope, because after backup I got: Code: text Expand Select all Copy to clipboardCRC should be d5b462cf CRC is d4232b4b CRC check failed Wrote 200000 bytes to firmware_backup.bin This CRC check comes repeatedly with exact same CRC values: so it is no coincidence, isn't it? Can you please check the file if it's okay due to this CRC fail? (See attached bin-file) 2) FLASHING: Tried to flash using: Code: text Expand Select all Copy to clipboardpython3 uartprogram OpenBK7231N_QIO_1.15.591.bin -u -d /dev/tty.usbserial-1410 -w -s 0x0 -b 115200 and I seem to get a bus connection, but a write error too: Code: text Expand Select all Copy to clipboardUartDownloader.... programm.... WriteSector 1 Failed: |                                              |[    ?k/s] Tried several times with no success: any idea? Help would really be appreciated - thank you!

gramais · Answer

... interesting:

Although reading worked as I got the backup I posted here before, writing does not.

But,

when I set the baud rate to 460800 (and only at this rate) I get at least a starting, but then immediately aborting flash process:

UartDownloader....
programm....
WriteSector 1 Failed: |1                                             |[ 3.31s/k]

p.kaczmarek2 · Answer

First of all, the CRC code is not updated for N so the warning is normal. It's okay.

And regarding WriteSector failed.... hm, how do you reset? I had this issue while I was resetting too quickly... the reset should be really, just 0.25s short on CEN.

btw how did you solve that strange Python problem from the several posts above?

gramais · Answer

Take a look at this:

Welcome to the world Newby-Born-OpenBEKEN!

So YES - YIPPPEEE, it worked!

Followed this post...

https://www.elektroda.com/rtvforum/topic3874289-180.html#20252165

... in which there was described a similar situation:

- reading (backup) possible
- baudrate issues same
- writing not possible

ALL as described above and in that post.

Aaaand this post even became identical as I read he used a MacBook Pro (as me). So the ONLY thing I changed was connecting the USB-UART-Dongle to my RASPBPI. Result:

user@raspberrypi:~/hid_download_py $ python3 uartprogram OpenBK7231N.bin -u -d /dev/ttyUSB0 -w -s 0x0 -b 460800
UartDownloader....
programm....
Write Successful: |##################################################|[ 9.14k/s]

So this similarity is surely no conincidtance and clearly a macOS issue. At least users should be warned or GitHub code should be updated. If I can help to finde out the reason: let me know what I can do!

p.kaczmarek2 · Answer

Well done, I don't have much experience with macOS so I was not aware about it.

If you want, you can do the honors and submit a pull request with readme update here:
https://github.com/OpenBekenIOT/hid_download_py
so your Github account will show up as a contributor - it's always good to be remembered as a person who helped with testing the tool.

So now, it seems your next steps are here:
Door/window sensor without TuyaMCU - deep sleep and energy saving, OpenBeken

gramais · Answer

Okay, tried to set it up as described:

P24 (PWM4) Btn => 1
P26 (PWM5) DoorSensorWithDeepSleep => 0

Saved and rebooted, but how can I check before adding to HA if it works?
How can I check if I used the correct PINs?
Can I see sensor state results in the web frontend?

And there is actually one issue: it loses WiFi connection. No ping or web request wakes it up....
:(

Needs there anything else to be configured?

Added after 36 [minutes]:

I am asking this because the sensor publishes a state correctly via MQTT that is displayed in HA but does not change: so I suppose that I have maybe chosen the wrong PINs? This suits the fact that the device falls asleep, loses WiFi connection and does not come back even if physically triggered: so there is no wake up command from a recognized sensor state change, right?

When looking at the board picture (in my very first post) the magnetic contact sensor is marked as "H1" - is that helpful?

Any suggestions?

p.kaczmarek2 · Answer

Device has to fall asleep in order to prolong battery life. Otherwise it would discharge battery in a day. While asleep, the website has to be offline, otherwise it wouldn't sleep. The only thing that can wake up correctly configured device is a button or sensor event.

The problem seems that you have selected wrong pin for button and the sensor. Now you have to put out batteries, wait several minutes or more for capacitors to discharge, because they can still hold current, and then finally put batteries again and quickly disable DoorSensor pin and driver. Then reboot.

Once you are sure that device is not running door sensor anymore, carefully investigate which GPIOs are really used for button and for sensor.

You can try setting a dInput role for each pin and checking which one reacts to door magnet.

The correctly configured device should wake up on both door sensor and button events.

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.

gramais · Answer

Okay, but how do I investigate - step by step? Does it involve the use of multimeter - and if yes: how? Thanks again!

dheenhasty · Answer

2 choice :

- With multimeter in diode you check which pin of the hall sendor is conected to cbu

- thru webapp, as p.k say assign each pwm pin to dinput with different channel and check wich one pass from 1 to 0 when you close or open the door

p.kaczmarek2 · Answer

Maybe it would be a good idea to create a Youtube video about that, for our Elektroda channel? Btw it looks like @gramais has cleared RF partition and lost MAC?

gramais · Answer

Why that: why do you think I cleared RF and lost MAC?

p.kaczmarek2 · Answer

@gramais please read our FAQ: Those two questions:

gramais · Answer

Ahhh - I see: thank you!Still no windows around: What would be the Linux command for the command-line tool?

p.kaczmarek2 · Answer

What do you need command line tool for? RF restore is done from within flashed firmware level.

gramais · Answer

Sorry, my fault: I was mistaken the web app with GUI flash tool - thank you for your patience!

khafif · Answer

>>20486194 I do not know if I am late, but if you work it out you can see what's in the back just by lifting it a bit.Added after 3 [minutes]:

khafif · Answer

I have same BK7231N/CBU Tuya door sensor, I’ve been trying to find the firmware, can you please link it, also can you advice how I can connect it to mqtt/home assistant (in detail please). Thank you.

simovicsava · Answer

Guys, I found the correct settings1. Sensory → Configure module:P16 DoorSnsrWSleep_nPupP20 BtnP23 BAT_ADCP26 WifiLED1. Flagi → Configure general/flags:X 10 [MQTT] Broadcast self state on MQTT connectX 35 [HASS] Deactivate avty_t flag for sensor when publishing to HASS (permit to keep value). You must restart HASS discovery for change to take effect.X 37 [WiFi] Quick connect to WiFi on reboot (TODO: check if it works for you and report on github)Code: text Expand Select all Copy to clipboardmqtt:   binary_sensor:   - unique_id: long name sensor     name: short name sensor 0     state_topic: short name sensor/0/get     qos: 1     payload_on: 1     payload_off: 0

p.kaczmarek2 · Answer

Very good, I would only add that automatic HASS Discovery should be already working for that kind of devices, so you don't really need to write YAML manually.

But you have exactly the same device as we spoke about, right? If not, please post the picture.

simovicsava · Answer

Yes Added after 9 [minutes]:It already works automatically adding to HA, but it shows the reverse status. When the sensor is open it shows that it is closed, and when the sensor is closed it shows that it is open

p.kaczmarek2 · Answer

Hmm, so you basically want to invert the reading of DoorSnsrWSleep? I can add a flag for that.

simovicsava · Answer

Yes, please

khafif · Answer

>>20638363Great work. Still learning from Elektroda and from you, thank you.Can you please advise how to reduce/change sleeping time.

p.kaczmarek2 · Answer

Hello, do you want to reduce the emergency sleep time when there is no MQTT, or the generic sleep delay that happens when MQTT is connected?

[BK7231N/CBU] Door sensor without TuyaMCU - how to connect to UART RX/TX

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