Identifying and Flashing Generic Tuya-Compatible LN882HK-based RGBCW Smart Bulb

Here is a LN882HK based smart bulb (RGBCW) that a friend of mine got a bunch of on AliExpress and gave some surplus ones to me:
Link.




I can't seem to be able to identify a brand (if there is one), but it is advertised as being compatible with the Tuya ecosystem.
The bulb itself also looks very generic. Removing the lid shows an LED shield with an outer circle of alternating pairs of cold/warm white LEDs, and within 2 rows of 3 multi-cathode RGB LEDs
   

Removing some thermal glue from the other edge allows the LED shield to be removed, exposing the main PCB: 

Note that the N contact is soldered to the tip of the bulb, whereas the P contact is just clamped between the upper end of the bulbs thread and the lower end of the plastic housing - no idea if this is considered a safety hazard, and also almost impossible to reassemble in the same way. I ended up pulling out the P wire and unsoldering the N wire from the PCB, trying carefully not to burn or break anything.
The controller used is a LN882HK, where neither the company in general nor the chip itself are known to me or anyone else I know.

Naturally it is also not supported by ESPHome, which led me to do an online search that quickly brought me here.

The backside exposed 2 pairs of UART TX/RX, where U0 is used for flashing and U1  probably as log terminal (I can only guess, since I didn't need to use it) , 3V3 supply and GND as well as a CEN (chip enable, not needed for flashing) and P21, which needs to be pulled to GND for flashing through UART. 

Red box: used for flashing
Yellow box: debug output (?) 

Note that at the bottom right, you can see the cathode connectors of the corresponding LEDs (RGBCW) - the transistors driving them are connected to: 

P09/GPIOA1 -> C
P12/GPIOA4 -> W
P13/GPIOA5 -> R
P14/GPIOA6 -> G
P15/GPIOA7 -> B

For flashing, I used a USB to UART/TTL adapter (3.3V) with the following connection:
U0-TX -> RX
U0-RX ->TX
GND -> GND
3V3 -> 3V3 (benchtop PSU, current limit 500mA)
P21 -> GND(during flashing)


For flashing OpenBeken, I followed the description in the flashing guide in this forum(Link) as liked on github. 
Flashing worked without any problems - after removing the short between GND and P21 and power cycling, I was able to connect to an OpenLN882H_C25E1088 hotspot. 
Configuration and HomeAssistant integration worked without any hickups, so I'll not go into details  here. 

Using the GPIO finder, I managed to confirm the connections of the LED groups as I suspected from the PCB: 





However, here is where I ran into some issues: 
If I configure the pins as relays, I'm able to switch all 3 colors (RGB) plus cold/warm white without issue. If I configure them as PWM, I can only use G/B + warm white. 

I'm not sure whether this is due to the LN882HK (maybe they use timer sharing for PWMs, or the pins need to be configured in a certain way) or just some oversight on my side - maybe I'll look into it some more if I find the time. Also if anyone has an idea what could be the issue, please reach out!

Summary:

My main aim was to have a dimmable warm white smart bulb, and thanks to OpenBeken and the instructions on this forum, I managed to get it working within on evening. The one issue remaining is the 5 simultaneous PWMs not working atm, but with an obscure chinese platform such as the LN882, and with such limited background information for developers available (that is not chinese), I think the mere fact that it is working at all is remarkable.
You have certainly done an amazing job portin OpenBeken to so many platforms as well as provide such detailed instructions on how to flash and use it!

Many thanks for that, I'll try to provide info on any compatible devices that I come across, as well as any bugs or issues with the software, should any pop up.

See here for current status of PWM development on LN882H https://www.elektroda.com/rtvforum/topic4065031.html

The most recent changes by @insmod have not been merged yet into the main build. Give the firmware from here a go https://github.com/openshwprojects/OpenBK7231...actions/runs/10745595504/artifacts/1903211551

>>21229188 Thanks, I'd gladly try it out but the link seems to be dead (or I don't have access to it).

I forgot you'd need to be signed into GitHub. Attached anyway.

>>21229885 Works perfectly, thanks!

Thanks for confirming/testing

@caelaron @davidezborges would you be willing to share the backups of factory firmware from your LN882H devices?

>>21279370 Gladly, how can I upload them to the forum?

this option allows the attachment of .bin or .zip files

here you go, otp and flash. i couldn't decompress the flash file using binwalk (it says xz compressed data) but you might actually make something out of it.

Hi there, I have the same smart light bulb I got from Aliexpress. I did get a backup and flashed already the latest firmware for the device OpenLN882H_1.17.767.bin so far everything went alright with flashing the bulb. I have access to the device Webserver to configure the smart bulb, in the configure section I did set "configure module" with the values 1-4-2-0-1 as in the picture, but the bulb is not responding. I also noted there is no driver being used. I'm new here, perhaps I'm missing something obvious or some details related to the setup. @caelaron @davidezborges I would appreciate some guidance on how to set up the bulb and make it work, at this time the lights are off at all times. Attached some pics and the backup of the original vendor firmware of my device.
Ps, I just added a pic of the LED's plate, beside the printed dates it seems the same as the one in the first post.

>>21296286 were you able to configure the device?
if not, connect to a wifi network and use the web application to test different templates. if that doesn't work, you should use a multimeter and trace the pins used to control the LED and start from there.

Hello,
quite new here. Nevertheless, it seems that I have the same bulb, flashed it with success. but then I couldn't find any matching and working template.
Thus, I applied manually the configuration shared at the top,
.
And it's working as expected, until some random time when the bulb turn off and disconnect.
My only option is to switch the lamp electrical power off => on, and wait for the bulb to get back. Sometimes it's immediately, other times I have to wait.
Thus, I feel like a limit is reach at some point, maybe a temperature one, and makes the bulb to set down.

Do you have an idea what's going on or/and how to fix it?
Is it maybe a slightly wrong configuration? Or maybe a flag/option could help (I'm very new to OpenBeken firmaware)?