Cheap UK WiFi Bulbs with Tasmota - teardown help (TYWE3S)

Hi all,
First of all I’m looking to see if anyone else has found luck with a Tasmota friendly B22 style bulb with decent light output/brightness?

I took a gamble and bought one off these off eBay:

Tearing it down reveals the following:

By the looks of it this seems to use a SM16726 LED module and a TYWE3S module (the green board which is perpendicular to the LED board). Has anyone had experience with this module before and flashing Tasmota on it? There seems to be a GitHub issue with some people having some luck over here

Alternatively I can buy another bulb but it’s difficult to find B22 style bulbs which will work with Tasmota.

Thanks for your help!

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You could just get cheap ES to B22 adaptors from Ikea etc and expand your choice to all bulbs, would depend on whether they would work with your light fitting though obviously as they’d make the ‘bulb’ taller.

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Hello mate,

I got a couple of these too. Had a ball programming a Sonoff 4CH box and 3 x ESP8266 bulbs with different drivers. No problems at all.

Like you, took a punt at these ones, only to open them up and see this. Looking at the specs for a TYWE3S module, our first problem is going to be getting at the pins. I had a go at one of mine last night, and the board is very well secured to the base, there is going to be a high risk of damaging it while trying to lift it, even attempted externally heating it to loosen the glue to no avail. The other one I haven’t even been able to get the cover off yet. TBH, I am genuinely surprised by the build quality, almost makes me want to put up with unfettered Chinese server access to my network and SSID password…

Have you had any luck?

@Bobby_Nobble Yeah I think that’s what I’m going to do for my next bulb so I can keep my options open, I’d like something with an adjustable cool-warm white and decent colour output so now all I need to do is find one!

@jgrob1 To be honest I’m not that much of a hardware hacker, so because the pins are within the casing I’m probably not going to try and break it open to get in to it, it sounds like it’s pretty solid based on what you said.

I currently have it on a separate SSID and VLAN with limited internet connectivity. After sniffing the network traffic, I can see it is talking to a German AWS IoT MQTT server and the traffic isn’t over TLS, so tonight if I get time I’m going to try redirecting the traffic to my own MQTT server. If it isn’t possible to flash custom firmware, I’d like to get to a point where I can at least control it through home assistant locally so the bulb can sit on a network with no internet access whatsoever. I’ll keep you posted on how I get on :slight_smile:

Hi all,

Got one of these el cheapo bulbs yesterday and i’d like to get to the pins on the tywe3s to flash it with something better. Looks like it is firmly glued in, indeed, and brute force might damage it. I wonder if applying some ipa (rubbing alcohol) might dissolve/soften the glue in order to lift the pcb. I’ll give it a go later this week and report back if successful.

@henkez73 That would be great, thanks!

Meanwhile I had a look a bit more into what the stock firmware is doing, the MQTT traffic seems to be in plain text but the messages contain an encrypted payload.

There is some information here:

It seems like it will be possible to control these devices locally with further inspection, but I’m not sure whether it will be worth it if it’s relatively easy to flash custom firmware.

EDIT: I’m also wondering whether it’s possible to push custom firmware as it seems like the device has OTA update capabilities. I might have a look in more detail soon.

On a slightly unrelated note, has anyone figured out how to operate the cool-warm white temperature adjustment? In the smart home app there is only the selection of colours, and then brightness for white, but no colour temperature.


I’m really happy with the rgb Yeelights, I only use them as white bulbs as the white has a very good range of adjustment independent of the disco light side.

@jamie15 yeah, I think the ota goes via HTTPS… worth having a look. Pretty sure I saw some documentation on the ota on tuya site…

Seems like i will need to go and find some rubbing alcohol as the mrs says we have none left…

it does seem to briefly show a warmer white when starting up initially, so it must be able to change the colour temp but nothing in the app to be able to adjust this…

If it could be softened with alcohol it could probably also be done with a hair dryer.

@Bobby_Nobble - You might be right and isopropyl alcohol won’t do anything.

The body of the bulb is heat conductive for a reason. It works as a heat sink for the power supply and it does get warmish to the touch. My guess is that a thermal adhesive (perhaps epoxy) has been used. Potential options then are either acetone, isopropyl alcohol, freezing… ordered some new 99.9% isopropyl alcohol off eBay, we’ll see.

I noticed that the slits in the aluminium body are open and you can see the glue on the back of the led pcb. With the ipa and a tiny screwdriver I removed the glue that I could see there and whatever I could get to from the front but it still isn’t budging… The white bits of glue I peeled out seem to be quite hard/brittle…

I have bought bulbs with the same PCB but E27 thread. I thought that I’ve bought some Sonoff bulbs to use them with Tasmota or ESPeasy. So I was a bit shocked as I’ve seen another PCB. Bad luck, it was a fake description at eBay.
I guess that the TYWE3S (Tuya ESP8266 module) board is connected to the upper board via the 8 way connector. The SLM211A is a constant current LED driver with PWM dimming control (datasheet (malware warning before visiting site): PIN 3 of this IC is connected to “CW” via 800ohm, PIN 7 is directly connected to (only some?) white LEDs. The connector PINs beside “Rc” and “Rd” are connected to SM16726 via 1kohm.
So I will try to flash the ESP8266 on the weekend by using “WW” as Rx, “CW” as Tx and “Rc” or “Rd” as boot pin (or all other pin combinations). Before I have to measure whether the level is 3.3V or 5V.

The bulb uses the TYWE3S module. Pinouts and info are here

You can unscrew the base and pull out the power board which has the module soldered on top. RX pins are accessible (they’re top right near the electrolytics and the pcb connecter that goes to the LED board)

I’ll have a go at hooking it up and dumping the firmware.

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Thank you, good to know that it is possible to unscrew the base. Be careful, I teared off the resistors leg.
When the bulb is turned on I measure 20V between VC and GND of the 8 way connector.
I measured connections like this (according to
GND: VCC ???

As this make no sense it is mirror inverted maybe:

VCC is probably converted down to 3.3V from 20V?

With both assignments it is not possible to flash the ESP8266 via the 8 way connector.
So you have to unscrew the base like rockofclay said.

Yeah the pinout on that page is from the back of the module. If you look at the back you should be able to make out the test pin to orientate. Vcc of the module should be 3.3v (that’s what the esp is).

It doesn’t seem to be connected to vcc of the led board, That will probably be a high voltage to directly power the leds. My module appeared to not even have the rx and tx soldered. Should be easy with a couple of fine patch wires.

Yes, flashing this TYWE3S board would be the smallest problem now. I think this circuit is not supported by any open source firmware like ESPEasy, ESPurna, Tasmota, etc. right now, is it? I’m a bit confused by the SM16726 IC if this makes the code hard to adopt.

Just wondering if this is in essence is an esp8285 (8266 with on board 1M flash)…



It’s an Espressif ESP8266EX

Has anyone had any luck with this in the end?

I’ve had some time today so I’m looking at figuring out how the OTA works to see if there is a way to load custom firmware. @henkez73 My initial investigations suggest that everything is over HTTP so it could be a lot easier than I thought.

I took mine apart and flashed Espurna to it, now that I’ve put it back together I can reflash espurna to it through the wifi without having to touch it.

The white channel can be controlled by just PWM’ing pin 5 but I haven’t yet had any luck talking to the SM16726 driver IC. I’m hoping that the protocol will be compatible with a more popular chip so I’m going to go through the list of protocols that the excellent library FASTLED implements and see if any of those work.

I have only so far found a chinese language datasheet for the SM16726, so if anyone speaks mandarin or has an english one that would help with figuring it out!

It’s convenient to glue a little header to the end of the TYWE3S module so that you only have to disassemble it once and can reflash even if your OTA upload breaks. Here’s what mine looks like now: