Just did some tweaking with some manually flashed Tuya sockets I have laying around. Sharing the configuration I built up after some soldering/multimetering and calibration. YMMV of course!
The important parts:
substitutions:
bl0937_voltage_divider: "750"
bl0937_current_resistor: "0.0025 ohm"
# The main relay is connected to P26
switch:
- platform: gpio
name: Socket
pin: P26
id: socket1
on_turn_on:
then:
light.turn_on: led1
on_turn_off:
then:
light.turn_off: led1
# The button on the side of the socket is wired to P11
binary_sensor:
- platform: gpio
pin:
number: P11
mode:
input: true
pullup: true
inverted: true
name: Button
on_click:
min_length: 50ms
then:
switch.toggle: socket1
# The LED is directly controlled via the state of the relay with the switch above
light:
- platform: binary
name: "LED"
id: led1
output: light_output
internal: true
output:
- id: light_output
platform: gpio
inverted: true
pin: P8
# The pins were checked with a multimeter and the datasheet for the built in BL0937.
sensor:
- platform: uptime
name: Uptime
- platform: internal_temperature
name: "Internal Temperature"
- platform: hlw8012
model: BL0937
cf_pin:
number: P7
inverted: true
cf1_pin:
number: P6
inverted: true
sel_pin:
number: P24
inverted: true
current:
name: BL0937 Current
voltage:
name: BL0937 Voltage
power:
name: BL0937 Power
energy:
name: BL0937 Energy
voltage_divider: $bl0937_voltage_divider
current_resistor: $bl0937_current_resistor
update_interval: 10s
The full config I was using for flashing is available here: ESPHome config for a Tuya CB2S WiFi smartsocket · GitHub
Pre-reqs:
- Make sure you understand what pins are what on CB2S - LibreTiny
- Get a solid 3.3V power supply (I used a 5V 2A power supply connected through a LM2595 DC-DC step down converter, turned to 3.3V (checked with a multimeter)
- Get a USB ↔ UART converter
Wiring:
- Connect GND on the USB UART to the GND on the power supply + a loose ground (you’ll need to tickle the CEN pin on the CB2S later)
- Tack Solder the above GND to network to the GND on the C2BS
- Tack Solder 3.3V from your power supply to the 3.3V pin on CB2S
- Tack Solder TX on the USB UART to RX1 on the CB2S (P10)
- Tack Solder RS on the USB UART to TX1 on CB2S (P11)
You should have:
- 2 wires from the power supply to the CB2S (GND + 3.3v)
- 3 wires from UART to CB2S (GND + TX + RX)
- 1 loose wire for ground
Flashing instructions:
- Run ESPHome dashboard (I use
docker run --rm -v "${PWD}":/config --device=/dev/ttyUSB0 -it --net=host ghcr.io/esphome/esphomefrom a machine with docker) - Setup a new device. If you don’t have the Libretiny options, you may still have luck with just setting the bk72xx directive.
- Install button
- When it compiles, it’ll eventually say it wants to upload the new firmware. It might even give you a wiring diagram telling you the above wiring diagram. You now want to short the CEN pin to GND. Touch the loose GND wire that is connected to the GND network to the CEN pin on the C2BS.
- When this doesn’t work, try again. It’ll eventually work
If you have no luck, try ltchiptool gui. I had some luck getting the device into a serial mode by using “Check Chip Info” and getting a valid display. At that point - assuming you don’t disconnect anything - flashing in the ESPHome dashboard should work.
Disclaimer:
- You are soldering wires onto a PCB - you’re voiding warranties and have a chance at bricking the device.
- You are flashing a custom firmware to a mains voltage smart socket. Don’t be ignorant with mains voltages, you might only get one chance in the remainder of your life to play with these things.
- If your house burns down, I take no responsibility
If you did the above successfully, congratulations! You now own the device you brought 
May I add, that in my case (maybe just a different board version) the button is connected to P23 (ADC) instead of P11 (TX1).