Tuya WiFi Energy Meter PM01_A002 [CBU][BK7231N] HLW8112 SPI Power Reading Ratio 1:5?

I'll start a dedicated thread for this device.

In another thread, a similar power meter is covered, but there'are mixed messages referring
both devices, causing a little bit of confusion. (https://www.elektroda.com/rtvforum/topic4016609.html)

The device I'll cover in this thread is the following:

      

Bough from Aliexpress: https://it.aliexpress.com/item/1005007292927857.html

What are my findings:

- HLW8112 (https://redmine.laas.fr/attachments/download/3444/DS_HLW8110_HLW8112_EN_Rev1.01%20.pdf)
- Unstable firmware (at least in my device)
- Power MeterIC connected directly to CBU module via SPI (NO TuyaMCU)
- Backup and restore firmware causes wrong measurement, but subsequently I discovered that all power values are reported in a ratio 1:5

By reading the posts from the other thread I concluded that there is no way to use TuyaMCU driver because the Power Meter IC
is directly connected to the Tuya module via SPI.

In fact @dicamarques made an attempt to write a driver for it (21221637#21221637), but, at least with my device,
by compiling the code he wrote from his GitHub repo, I was unable to get SPI working.

Furthermore Dicamarques and other guys posted a lot of useful informations:
- a schematc where you can see that P9 is used for "SCSN"  instead of the standard P15.
- links where very complete and presumably working drivers can be found

Subsequently I wanted to try to write my own driver... 
Spoiler  I wrote a lot of code, half of it, copy/pasted from the full driver source from the link above, but with no luck... the SPI still not send or receive data.

This i the link to my repo, in case someone more experienced can tell me what I'm doing wrong  https://github.com/kaleidoscopeit/OpenBK7231T_App_HLW8112
(--> To start the driver, issue "startDriver HLW8112SPI" in the command field of the log console in the Web Application)

It could be that I'm doing something crazy, like buying a logic analyzer and connect it to the SPI in order to understand what goin on when
the original Tuya firmware speaks with the Power Meter IC.

I thank the guys who posted in the other thread and I invite everyone to continue in this one.

Interesting, have you seen BL0942 SPI driver in our repository? Maybe it could serve as a reference.

Hi, yes I used it in order to build the base structure and get useful hints on how to write a driver. Thank you.

I've updated the main topic message with the link to my fork of OpenBK7231T_App.

I think you should start with the most basic transmit and read code. Try to choose some register from HLW datasheet and then try to read it with OBK.

@kaleidoscopeit
Hello. i have written something for hlw8112. I also have device and tiered of tuya firmware issues. If you still have device and willing to test please try mine and would welcome any feedback
this is my first openBKN adventure i have no idea most of the things are supposed to work. So far I have got voltage, frequency current A/B, power A/B, energy ( import/export ) A/B. active power and power factor, homeassistant discovery
https://github.com/netmaxt3r/OpenBK7231T_App/tree/hlw8112
you can download build for OpenBK7231N build from GH actions.
DONOT run firmware on the device for long as I still haven't figure out some stuff. might cause a lot of flash write which may cause degradation ( I dont know). Just test for some time and let me know how it goes my device template is this



i still need to work on
calibration params
align code to existing power meter drivers etc.

@p.kaczmarek2 nice job on OpenBK. as you can see my code is spaghetti right now. that is why i haven't opened PR on github. I am not a real C developer. I have couple of questions on how to fix it and properly integrate with platform. Where do you prefer github PR or here ?.
Thanks for your time.

Thank you. As long as your driver is in separate file (‎src/driver/drv_hlw8112.c in your case, I see..), and you do not modify much of the obk core API and stuff, then I can easily accept PR. Just make sure your code is not build on default and encased in ENABLE_DRIVER_HLW8112SPI, also make sure that everything builds correctly with no errors. Then I can merge via PR on Github.

The only stuff you need to fix/remove before merge is this:

sure, i will create PR early next week with all the build issues. meanwhile could you help with some questions

1. Is it okay if my driver hijack current emetering struct (only if my driver is running) ? i tried to add new struct to flashvar and device refuse to boot past flashvar init. i think i need to make flash reinit i don't know how.
2. Currently I have home assistant button sending mqtt topic to /command/dev_name/<cc> . Is this the correct way?. I have a feeling i should use channel for this
3. Do I need to align with existing BL_ drivers ?. It might take more time to understand especially BL_TWIN logic
thanks

Hey @p.kaczmarek2 I have created a PR https://github.com/openshwprojects/OpenBK7231T_App/pull/1810
driver is disabled in the code. please have a look and let me know

>>21694008

Script execution log:

Send started... send 0/9... send 1/9... send 1/9... send 2/9... send 2/9... send 3/9... send 3/9... send 4/9... send 4/9...FAILED! Invalid command "backlog setPinRole 9 HLW_8112_SCSN; setPinChannel 9 0".FAILED! Invalid command "backlog setPinRole 9 HLW_8112_SCSN; setPinChannel 9 0".

Button looks interesting, but it's not called anywhere? Still, probably worth keeping...

So this device can't easily mix with bl_shared because it has dual measurement, A/B? I see... I guess it's acceptable.

Okay, but is your branch still working with BL0942, BL0937, etc? @divadiow can you check before merge?

BL0937 I can do now

1810_merge_183015c253a3

driver starts and readings are showing as before

my hlw8112 is still not working, can someone share pin details

kdm6389 wrote:

my hlw8112 is still not working, can someone share pin details

are you running the PR build 1810_merge_183015c253a3?

Built on Sep 28 2025 08:25:04 version 1.18.181
Online for 3 minutes and 18 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

Added after 16 [minutes]:

updated to

Built on Oct 1 2025 22:31:45 version 1.18.185
Online for 3 minutes and 39 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

using https://github.com/openshwprojects/OpenBK7231...es/download/1.18.185/OpenBK7231N_1.18.185.rbl
installed just now,

still not working ....

if there is pin configuration / setting to change please do share for both (A/B) channels

trying https://www.elektroda.com/rtvforum/topic4130528.html#21694008


Script execution log:
Send started... send 0/9... send 1/9... send 2/9... send 3/9... send 4/9... send 5/9... send 6/9... send 7/9... send 8/9... Send done! Please restart device if needed.



still not working ....

I don't think this driver is enabled by default on the public build. You need to enable it in obk_config.h. If you do startDriver for it, does it even start? I don't think so - it's not in the build.

hello,
test with this build

How to flash bin file there is no option

With ota file

Built on Oct 1 2025 22:32:02 version 1.18.185_powerMetering
Online for just 25 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

this one also not worked

ref:
https://github.com/openshwprojects/OpenBK7231T_App/releases

Added after 2 [minutes]:

>>21707699 let me check it has rbl

Added after 3 [minutes]:




Built on Sep 27 2025 12:50:21 version 1810_merge_183015c253a3
Online for 1 minutes and 9 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

no power output? why?
I think I need the config?



cmd:
startDriver HLW8112SPI


Info:MAIN:Driver HLW8112SPI is not known in this build.
Info:MAIN:Available drivers:
Info:MAIN:TuyaMCU
Info:MAIN:, tmSensor
Info:MAIN:, PixelAnim
Info:MAIN:, NTP
Info:MAIN:, HTTPButtons
Info:MAIN:, I2C
Info:MAIN:, BL0942
Info:MAIN:, BL0942SPI
Info:MAIN:, BL0937
Info:MAIN:, CSE7766
Info:MAIN:, SM16703P
Info:MAIN:, SM15155E
Info:MAIN:, IR
Info:MAIN:, DDP
Info:MAIN:, SSDP
Info:MAIN:, DGR
Info:MAIN:, Wemo
Info:MAIN:, Hue
Info:MAIN:, PWMToggler
Info:MAIN:, DoorSensor
Info:MAIN:, SM2135
Info:MAIN:, BP5758D
Info:MAIN:, BP1658CJ
Info:MAIN:, SM2235
Info:MAIN:, CHT83XX
Info:MAIN:, KP18058
Info:MAIN:, ADCSmoother
Info:MAIN:, AHT2X
Info:MAIN:, DS1820
Info:MAIN:, Battery
Info:MAIN:, Bridge
Info:CMD:[WebApp Cmd 'startDriver HLW8112SPI' Result] OK

>>21707701

you need to take a firmware with the driver built-in, it is not the case by default

this build has the driver enabled : https://github.com/netmaxt3r/OpenBK7231T_App/actions/runs/18059811136/job/51394535502
the firmware build is this one : https://github.com/netmaxt3r/OpenBK7231T_App/actions/runs/18059811136/artifacts/4121996251

which way you use to flash ?
with serial way it's OpenBK7231N_UA_hlw8112_6ae422624810.bin ( in zip )

================
back to
================

Built on Oct 1 2025 22:31:45 version 1.18.185
Online for 1 minute and 0 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

==========
Info:MAIN:Driver HLW8112SPI is not known in this build.
Info:MAIN:Driver HLW8112 is not known in this build.

============
but,
Info:MAIN:Started BL0942SPI.
Info:CMD:[WebApp Cmd 'startDriver BL0942SPI' Result] OK
works, which means HLW8112SPI still disabled

Added after 7 [minutes]:

>>21707751
This one worked

Built on Sep 27 2025 12:35:04 version hlw8112_6ae422624810
Online for 1 minute and 3 seconds
Device MAC: 38:A5:C9:42:DE:42
Short name: 0f-de-obkDE42, Chipset BK7231N

You take with firmware ?
I see Built on Oct 1 2025 22:31:45 version 1.18.185
The link I give you the firmware was built on Sep 27, 2:30 PM GMT 2

Thanks @feiltom

>>21707780

here's how it looks (both sensors are clipped to the same wire):

Hi everyone
Is there a fully working OpenBeken firmware for the Tuya power meter with HLW8112 (BK7231N)? I have been reading but I’m still not completely sure if there is already a fully working OpenBeken firmware that supports it. If there is a working firmware already, where can I download it?

Thanks a lot for your help

Hey, maybe in the Releases section?

https://github.com/openshwprojects/OpenBK7231T_App/releases

Thank you. I use a bk7231guiflashtool-v130 but the .rbl file is not accepted. How I have flash this firmware?

BK7231 Easy GUI Flasher requires QIO, however, you can just flash stock OBK qio as well and then do OTA to RBL. Maybe it's easier.