Teckin SB51 RGB Bulbs - access to pins to flash Tasmota firmware

gavraq · December 20, 2021, 8:53pm

Hi,

I am trying to flash Tasmota softawre onto a Teckin SB51 RGB bulb. I cant do Tuya convert since I had previously used the SmartLife app (once connected to the app they block the ability to do OTA updates using Tuya convert)…so I am left with the option of accessing the pins for the ESP8266 chip.

I have validated that it is indeed ESP8266 (since some of the older models no longer use this chip) and now I need to find the right pins to connect to upload Tasmota using UART.

If I understand correctly from my research I need to find the following pins:
+VCC (3.3V)
GPIO0
GRD
RX
TX

I have taken some photos after accessing the innards of the buld and here is what I get:

Most are pretty self explanatory except for the RX and TX but I can see 2 pins which are marked as:

W_PWM, and
Y_PWM

Would these be the RX and TX pins and if so which is which.

Thanks in advance
Gavin

FransO · December 21, 2021, 10:48am

No, PWM stands for Pulse Width Modulation by which Red Green Blue light levels are controlled.

gavraq · December 21, 2021, 5:50pm

Hmm, ok back to the drawing board then.

Any suggestions based on theses additonal photos of the ESP chip?

FransO · December 21, 2021, 6:47pm

Search for esp8266ex pinout. This is the pinout of the chip, not the board.

gavraq · December 22, 2021, 4:15pm

ok, I think this is well beyond my knowledge. Is the esp8266ex pinout related to the RX and TX pins?

FransO · December 23, 2021, 1:31pm

The Esp8266EX is the big square chip with 32 terminals on your last photographs. The orientation is with the dot in the upper left corner and the text right side up.
Terminals 25 and 26 are RX and TX, terminal 15 is GPIO0. 3.3V and ground you’d better take of the board, not the chip. Take care not to heat the chip overmuch to prevent damage to the chip. You need a USB to Serial converter to flash the ESP. Some USB to serial converters label the terminals as what you have to connect to, others what it is on the converter. So you might either need to connect TX-TX and RX-RX or TX-RX and Rx-TX. Try it out, that will nog damage anything.
Make sure that you do not connect mains voltage to the device while flashing, you could end up with a smoking PC. I apologize for overstating the obvious, but better safe than sorry.

gavraq · December 28, 2021, 9:11am

Thanks for the help Frans. I did manage to find out the right board layout after a lot of internet searching. The problem is that the pins are not accessible unless you pull the whole thing apart (which I have now done)…and then the putting back together is somewhat more difficult

Here is the layout for anyone else interested