How to Enable PWM Dimming on LN882HKI Tuya Smart LED Controller with OpenBeken?

Question

I successfully flashed OpenBeken to a LN882HKI device in the pictures. The device is a led panel for indoor plants: https://www.mother.life/BE/shop/linear

I can control on/off with LED or relay on A10 but it will not work with PWM. The local button works properly on B4 as seen in the config:

I cannot get the device to dim, however, which I'm guessing stems from PWM not working. Anyone have any ideas? I can provide more info from the Web App if needed.

p.kaczmarek2 · Answer

From a brief glance, it seems that PWM is not yet implemented on LN882HKI: Code: C / C++Log in, to see the code We need to check their SDK and add missing PWM calls. Would you like to help?

acbrooks · Answer

Yes, I can help with info from my device or testing.

parlaystaller_0d · Answer

Hi, did you manage to get this working?I am running into the same issue.

acbrooks · Answer

Not yet. I will need some handholding to provide whatever information is needed to get PWM working in this module.

p.kaczmarek2 · Answer

There are some PWM mentions in SDK: This seems to be a PWM header: But how do we know how to map PWM channels to GPIOs?

parlaystaller_0d · Answer

I would be willing to help but I don't have any experience with either low level hardware debugging or C coding...So, if there is anything I can do please tell me.

parlaystaller_0d · Answer

Does anybody know someone who can help out with this?

divadiow · Answer

I'm afraid I am not able to assist with this.

p.kaczmarek2 · Answer

Well, here is a full PWM sample: Code: C / C++Log in, to see the code We just need to find which port/pin combination is using which PWM channel. Maybe in some datasheet?

divadiow · Answer

all of the FULLMUX pins?

parlaystaller_0d · Answer

>>21181676 does this datasheet help us with understanding which pins are used together for PWM? I don't really know how to read this sheet and what to take from it...

divadiow · Answer

all I can add really is that our LN882HKI chips are QFN32 packages so the GPIOs that are FULLMUX, which I think includes PWM support, are

GPIOA0: Pin 8
GPIOA1: Pin 9
GPIOA2: Pin 10
GPIOA3: Pin 11
GPIOA4: Pin 12
GPIOA5: Pin 13
GPIOA6: Pin 14
GPIOA7: Pin 15
GPIOA8: Pin 16
GPIOA9: Pin 17
GPIOA10: Pin 21
GPIOA11: Pin 22
GPIOA12: Pin 23
GPIOB3: Pin 24
GPIOB4: Pin 25
GPIOB5: Pin 26
GPIOB6: Pin 27
GPIOB7: Pin 28
GPIOB8: Pin 29
GPIOB9: Pin 30

divadiow · Answer

maybe @max4elektroda or @insmod are in a position to assist

insmod · Answer

PWM demo, though not very good. The driver from have a stop function, so it is better to reboot after changing PWM pins.

parlaystaller_0d · Answer

>>21195618 thanks for providing an example.

I guess the next info I need is, how to find and configure PWM pins.
How do I know which of them is/are responsible for dimming the light?

Next, did I understand correctly, that I have to configure a PWM pin that controls channel 4?
When you look at the PCB, there are wires to C and V.

The current configuration has a pin configured as LED controlling channel 0.
And a button_SmartLED controlling channel 0.

insmod · Answer

>>21199706 If you are able to turn on/off light with LED on P10 pin, then just change LED to PWM. While your board has full rgbcw pins, only c is wired, so channels don't matter.

parlaystaller_0d · Answer

>>21199714 hmm ok, thanks for the info.

I figured out. why it is not working.
Somehow the OTA does not work.
When I try to upload your example binary, It says, starting OTA... But thats it. It does not reboot.
Do you have an idea?

Added after 14 [minutes]:

>>21199714 I got it wokring. I uploaded with another browser. Somehow Firefox had an issue with it ¯\_(ツ)_/¯

One last question, would mind, creating a PR with your changes?
I know it isn't finished but it at least works almost

I now have the issue, that MQTT disconnects and connects repeatedly and resets the light to a dimmed value.
Maybe there is some loop?

insmod · Answer

>>21199833 Will open, though first I have to remove the dependency on the driver from SDK. It will take some rewriting, but easily doable.

parlaystaller_0d · Answer

>>21199881 Thank you very much!

p.kaczmarek2 · Answer

Thank you, merged. So you basically pick first unused pwm channel?

divadiow · Answer

@acbrooks how are you getting on with the new driver? is it working or do you have similar experiences to me in this conversation:

parlaystaller_0d · Answer

Sometimes I have the issue, when it loses the connection to the MQTT server and it reconnects, it turns on the light to about 1 or 2 percent.
I don't know if this is specific to this controller but I don't think so.
Do you have any advice for that issue?

insmod · Answer

>>21223672 Controller-specific problem. If pin is not initialized, then that happens.
This is probably not needed for you, but if you want to transform your device to rgbcw then
https://github.com/openshwprojects/OpenBK7231T_App/pull/1331, fixes multiple pwm channels.

p.kaczmarek2 · Answer

Is PR 1331 ready to merge?

insmod · Answer

>>21223713 Yes, i verified that it works on a single rgb led. The only drawback, is that it reduces the available channels to 6, instead of 12.

p.kaczmarek2 · Answer

Can you explain what is the logic behind those channels on LN882H and why do we have to choose?

insmod · Answer

>>21223724 Each pwm timer have 2 channels, but when second channel is picked, it somewhy doesn't work. So rgb led witch channels 1r 2g 3b, the green channel didn't work. In my pr, it will select only first timer channel for each pwm channel.

divadiow · Answer

on 1331_merge_fe57bd70ce5e with these assignments Code: TextLog in, to see the code which translates to: I have 5 working LEDs, controllable as one would expect. Dimmable, colour picker, warm/cold so all looks good.