Discovering Pin-to-Channel Connections for PWM on Calex E27 LED Bulbs with BK7231T Chip

Hi,
I was working on a new breakdown of 10 Calex E27 light bulbs I got on ibood.com. I successfully dismantled one of the bulbs and found a BK7231T inside. Already flashed it with cloudcutter and now I am stuck.

I cannot find the correct PWM settings for the pins. Any tips on how I can determine with Pin goes to which channel...

Thanks
NIels

Added after 4 [minutes]:

After flashing the bulb is on, connected to the wifi and I am able to connect to the web interface.
However, after setting the PWM and pressing toggle once, the light goes off but I am not able to power the light on again.

Would incorrectly assigning the PWM potentially damage the leds? The web page keeps working fine though.

Niels

Added after 42 [minutes]:

Okay,
The Skylc5 module only has 3 usable GPIO pins; GPIO04, GPIO12 and GPIO14.
So I can't set 5 PWM's. Having said that, how can I map GPIO to P(n) ?
NIels

Added after 29 [minutes]:

Well I did some research and figured that GPIO12 points to PWM4, GPIO14 to PWM5 and GPIO4 to PWM1.

Configured them, but no luck, nothing lights.

Are you allowed to configure only one PWM, at least to figure out the correct pin? Or are all PWM's mandatory?

NIels

Hello, if it's really a PWM-based bulb (no SM2135, etc), then you can even set GPIO roles to RELAY and just toggle relays to see if it works.

You can also set PWM roles and enable "Show raw PWMs" in flags.

But wait...

Only 3 useable GPIO and RGBCW bulb?

That must be SM2135 or similar.

It must be either SM2135, or BP5758, or BP1658C, etc...

Please investigate the board and check the IC markings.

I'll do some further investigation. On the LED plate itself is no IC, so it must be somewhere on the PCB.
I will need to scrape off a lot of glue to find any IC. But at least I know what I am looking for now.
Once found will share and create a proper tear down
Niels

If you have a binary dump from this device, you can also use a cloudcutter profile to generate OBK config. Of course, it must be a cloudcutter profile of the same device model you have.

Well found it. covered under a lot of putty as sm2135. Now I'll trace the pons back to the skylc5 and see if I can get it to work.. [img-0]

Good job, it should be very easy to get it running now. Even while guessing, there aren't many possible combinations with SKYLC5 module which has few available GPIOs.

I agree; there are not many combos, but I am unsure of the mapping of the P-numbers.
When looking at the pin out of the TYLC5 (likely a very close clone) https://developer.tuya.com/en/docs/iot/wifilc5module?id=K9605t3bpxf75
I figured

CLK -> GPIO14 = P6
DAT -> GPIO12 = P7

No luck tried flipping P6/P7 still no joy. Now trying all combos..
But with 5 PWM's that is still a lot of combo's (625)...
Ant a chance we can figure it out easier?

Niels

Added after 25 [minutes]:

Okay,

I pulled out the magnifier, and based on https://jilles.com/img/tuya/SKYLC5-1.PNG I concluded that GPIO4 (right bottom finger) goes to the bottom pin on the right on the square beken chip. The only matching PWM is, based on https://obrazki.elektroda.pl/6366133600_1673944535.png , P25 PWM3.

When following GPIO12 and GPIO14 they connect to P23 and P24 (PWM1 and PWM2). As those are the only ones used I configured PWM1 for CLK and PWM2 for DAT, nothing happened (also not after reboot). I flipped the configure, so PWM1 for DAT and PWM2 for CLK, no joy...

I need to think this over, unless someone has a clue they want to share.

Niels

Added after 1 [hours] 31 [minutes]:

Nailed it!
I had to use PWM4 / P24 for SM2135DAT and PWM5 / P26 for SM2135CLK.

Need to play with the color map but it works.

Will now flash the remaining 8 bulbs!




Niels

That's quite a common choice of GPIO for SM2135:

I think I am almost there, and I can't figure out the SM2135_MAPS setting. However, I did the following, and maybe someone can help me with the correct MAPS setting:
When entering the color codes for RGB I get the following results
color #00FF00 -> Green -> blue
color #0000ff -> Blue -> red
color #ff0000 -> Red -> white

Clearly messed up, but how to apply the MAPS command so Green becomes Green, Blue becomes Blue and Red becomes Red.

Thanks
NIels

Start with map 0 1 2 3 4 and then, for example, if green is swapped with red, swap first and third number.

You can also use the LED_Map tool in Web App -> Tools

Well, as we checked all the boxes, I'll write a teardown this weekend and post it on the site.
If anyone is still interested, the lamps are available for € 2,99 (when buying a 5-pack).
https://www.ibood.com/offers/nl/s-nl/o/5x-calex-smart-led-lamp-e27/817983
Niels

Added after 7 [hours] 15 [minutes]:

Solved,

map order is:

1 0 2 4 3

Niels