Yeelight Smart Bath Heater (YLYB01YL)

[alex7hacs]

Dear @syssi ,
I have a Yeelight Smart Bath Heater (YLYB01YL, yeelink.bhf_light.v2) that is deeply mounted in the bathroom ceiling. After a pipe burst, water flooded the lamp and damaged the "daughter controller," which likely handles BLE and Wi-Fi communication.

I want to try replacing the "daughter controller" with a regular ESP32 dev board, at least to restore basic light control. What do you think, which of your firmware would be the best starting point? I hope the communication protocol with the main controller doesn’t vary too much between models.

Maybe you’ve seen something similar to this board?

[syssi]

Just some thoughts:

1. Let's try to get an idea about the different parts and features of your device (f.e. how does the mainboard look like? What's attached to CON1, CON2 and CON3?
2. What is the thing at the center of the second picture? A LED matrix which was used as low resolution display?
3. Does the heater still work?
4. Does the light turn on if we apply a PWM signal?
5. It looks like there are two I2C buses (SCL_D, SDA_D and SCL_S, SDA_S). What's attached to these buses? If you attach an ESP here and if we load the i2c component are we able to discover devices on the bus?

[alex7hacs]

1. Let's try to get an idea about the different parts and features of your device (f.e. how does the mainboard look like? What's attached to CON1, CON2 and CON3?

It consists of two parts:

• mounted in the ceiling (main controller, fan, heating elements, power supply). Unfortunately, it cannot be disassembled without damaging the ceiling, but I’ll try to figure out how to extract main board.
• removable part (daughter controller, main LED, low-resolution display). Only the part with the daughter controller was flooded.

There is a 22-pin cable connecting the two parts, and a 4-pin cable between the main LED and the daughter controller (it seems like the latter is directly connected to the 22-pin cable via the "daughter board"). The device supports 4 fan operation modes (heater on/off, etc.), with several speeds in each mode. Light on/off + night light on/off.

2. What is the thing at the center of the second picture? A LED matrix which was used as low resolution display?

Yes, it's low resolution display.

3. Does the heater still work?

It doesn't work without the daughter board. I hope only "daughter board" was damaged. I tested the voltage on the 22-pin cable, and it's OK.

4. Does the light turn on if we apply a PWM signal?

Yes, the light turns on when I use an external power source.

5. It looks like there are two I2C buses (SCL_D, SDA_D and SCL_S, SDA_S).

Thank you! I’ll try to figure out how to do this.