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Alternative/new GPIO pinout of TYWE3S/ESP8285 WiFi module, Tasmota

p.kaczmarek2 5811 5

TL;DR

  • A TYWE3S WiFi module in the Appio 9605 light switch uses a non-standard GPIO pinout that does not match Tuya documentation.
  • Inspection showed it is an ESP8285 with built-in memory, not the usual ESP8266 plus SPI flash, and the UART pins sit in different locations.
  • The module has 2MB built-in memory, and the alternative wiring for RX, TX, and GPIO0 allowed flashing Tasmota.
  • Standard flashing failed, but Tasmota uploaded successfully after using the alternative pinout; the new and old TYWE3S versions are hard to distinguish externally.
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  • TYWE3S module with an ESP8285 chip.
    Recently, while uploading Tasmota to another series of WiFi-controlled light switches, I came across something that really surprised me. It was a TYWE3S module with non-standard pinouts that did not match the Tuya documentation. Here I will provide its RX, TX and GPIO0 location and information on how to change its input in such a case.

    I found the module in the Appio 9605 light switch, but from what I saw, it is repeated in the entire Appio series. It may also be found in other products.
    Seemingly, it's an ordinary TYWE3S:
    TYWE3S module soldered onto a PCB with connected wires for firmware flashing.
    But standard flashing is not successful at all. For this reason, I desoldered it with hot-air:
    TYWE3S module on a circuit board next to a hot-air tool.
    I also removed the screen and started analyzing:
    TYWE3S module with open shield next to a circuit board.
    There is no ESP8266 + SPI Flash set inside, only ESP8285 with built-in 2MB memory.
    TYWE3S module with ESP8285 chip visible after removing the shield.
    This TYWE3S has no GPIO information on the description layer:
    TYWE3S module with non-standard pinout. View of the TYWE3S module with non-standard pinouts.
    TYWE3S module with exposed ESP8285 chip. Close-up of the TYWE3S module with ESP8285 chip.
    I was about to analyze the PCB carefully to see what goes where, but I found mentions of this module on the Internet:
    https://github.com/arendst/Tasmota/discussions/16500
    TYWE3S WiFi module with marked pins: RX, TX, GPIO0, GND, and 3V3.
    After soldering the wires according to the alternative pinout, I managed to upload Tasmota:
    TYWE3S module with soldered wires on a wooden surface
    I flashed according to: https://www.elektroda.pl/rtvforum/topic3990951.html
    Then I soldered the module into place.
    The module can probably be flashed into the system just like the old TYWE3S (as long as the UART port is not occupied, e.g. by TuyaMCU), but at the moment I don't know how to determine from the outside whether the encountered TYWE3S is "new" or "old"...

    Summary
    This module is described as TYWE3S but has pinouts that are incompatible with it. I guess only the ground and power supply are in the same place, but I didn't check other GPIOs either, because it's faster to just set 4 relays on the Tasmota and test the GPIO options one by one than to write it down. It can be distinguished from the old TYWE3S only by the fact that there is one ESP8285 under the screen, not ESP8286 + memory chip.
    For reference, I will remind you of the pinouts of the old TYWE3S:
    Diagram of TYWE3S module with crossed-out pin specification.
    I really don't know how this could have happened and what was the motivation for such a pin swap, especially since all "newer" modules such as WB3S or CB3S have pinouts compatible with the old TYWE3S (even the UART location is the same), and here the UART is in a different place, but at least VDD/GND has not been changed, so there is probably no risk of damaging this module...
    To sum up, I warn you - if you are unable to upload the firmware to TYWE3S, check if you have the version described in this topic.

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    About Author
    p.kaczmarek2
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    p.kaczmarek2 wrote 14589 posts with rating 12611, helped 654 times. Been with us since 2014 year.
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  • #2 20837223
    KarolJuszkiewicz
    Level 12  
    Posts: 183
    Help: 6
    Rate: 12
    So this is a WiFi switch?!
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  • #3 20837253
    p.kaczmarek2
    Moderator Smart Home  
    Posts: 14589
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    Rate: 12611
    TYWE3S is a WiFi module based on ESP8266 (or, as you can see, ESP8285), used in many Tuya products. Its documentation can be found here:
    https://developer.tuya.com/en/docs/iot/wifie3smodule?id=K9605ua1cx9tv
    In addition, there are also similar modules, such as TYWE2S, also for ESP, and modules on other systems, but compatible with pinouts (more or less), such as CB3S or WB3S.

    These types of modules can be found in various types of WiFi-controlled devices, for example in WiFi switches, or thermostats, or smart sockets (usually TYWE2S/CB2S/WB2S), and so on. Even in Blitzwolf's "smart fryer" (whatever it is) I saw TYWE3S.

    All this is interesting because such products can then be changed from a WiFi module to some open source software in order to free the device from the cloud and modify it at will.

    The full list of IoT devices we describe can be found in the link below:
    https://openbekeniot.github.io/webapp/devicesList.html
    The search engine supports searching by name, keyword and module name (enter "TYWE3S", select ESP and search)
    Helpful post? Buy me a coffee.
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  • #4 20845831
    KarolJuszkiewicz
    Level 12  
    Posts: 183
    Help: 6
    Rate: 12
    And what can you do with such a module? Since he surprised you
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  • #5 20845841
    p.kaczmarek2
    Moderator Smart Home  
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    But are you asking about the WiFi module itself or the switch?

    TYWE3S is a module very similar to ESP12. Of course, you can also buy it as a module only, without an IoT device:
    Image of four ESP8266-12F WiFi modules with price offers.
    In the normal, popular version, TYWE3S has pinouts compatible with ESP12, but in this topic I am describing its alternative version, where the pinouts are completely mixed up (except ground and power supply).

    You can implement many interesting projects on ESP12, e.g.:
    Clock on ESP12 and MAX7219 display - tutorial - part 1, ArduinoOTA, basics
    Helpful post? Buy me a coffee.
  • #6 20845849
    KarolJuszkiewicz
    Level 12  
    Posts: 183
    Help: 6
    Rate: 12
    p.kaczmarek2 wrote:
    But are you asking about the WiFi module itself or the switch?

    I'm asking about the module itself because I'm thinking about making a WiFi camera (I'll create a topic about it later).
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FAQ

TL;DR: For Tasmota users and repair hobbyists, some TYWE3S modules move 3 key pins and use "one ESP8285" under the shield instead of the usual layout. If flashing fails on an Appio 9605 switch, check for this alternate pinout before assuming the module is dead or locked. [#20835466]

Why it matters: A TYWE3S that looks standard from the outside can still fail every normal flashing attempt because its UART and boot pins are in different places.

Module variant Internal chip layout RX/TX/GPIO0 location Flashing outcome with standard TYWE3S wiring
Older TYWE3S ESP8266 + external flash chip Standard TYWE3S / ESP-12-compatible layout Works normally
Alternative TYWE3S Single ESP8285 with built-in 2MB memory Swapped relative to the older layout Fails until you rewire
WB3S / CB3S Different module families Described as keeping the older compatible layout Less surprising during rewiring

Key insight: The fastest diagnosis is physical: if the shield hides a single ESP8285 and normal flashing fails, treat the module as the alternate TYWE3S variant and rewire RX, TX, and GPIO0 accordingly.

Quick Facts

  • The reported Appio 9605 switch used a TYWE3S-labeled module that required an alternative RX, TX, and GPIO0 wiring before Tasmota would upload successfully. [#20835466]
  • The unusual module contains 1 ESP8285 with built-in 2MB flash, not an ESP8266 paired with a separate SPI flash chip under the shield. [#20835466]
  • On the alternate board, the author trusted 2 power pins to match the old layout: VDD and GND stayed in place while the UART location changed. [#20835466]
  • After installation, the author mapped functions pragmatically in Tasmota by assigning 4 relays and testing GPIO options one by one instead of tracing every connection. [#20835466]

What is the TYWE3S WiFi module, and how is it used in Tuya-based smart devices?

TYWE3S is a WiFi module used in Tuya-based devices such as switches, thermostats, and smart sockets. The thread describes it as an ESP-based module, usually similar to ESP-12, and notes it also appears in products like a Blitzwolf smart fryer. Its value is practical: you can replace the stock cloud firmware with open firmware and regain local control. [#20837253]

How can I identify a non-standard TYWE3S with the alternative ESP8285 pinout before trying to flash it?

Identify it by opening the shield and checking the chip arrangement. The alternate module has a single ESP8285 with built-in 2MB memory, while the older TYWE3S uses an ESP8266 plus a separate flash chip. From the outside, the author did not find a reliable visual marker, and the silkscreen lacked GPIO labels. [#20835466]

Why does flashing Tasmota fail on some TYWE3S modules even though they look like the standard Tuya module from the outside?

Flashing fails because some TYWE3S-labeled boards move RX, TX, and GPIO0 away from the standard TYWE3S positions. The module still looks ordinary externally, so standard wiring targets the wrong pads and boot mode never starts correctly. That mismatch caused repeated failures until the author rewired using the alternate pinout. [#20835466]

How do I flash Tasmota onto the alternative-pinout TYWE3S/ESP8285 module found in Appio 9605 switches?

Use the alternate pinout, not the standard TYWE3S one. 1. Desolder the module or access its pads safely. 2. Wire RX, TX, and GPIO0 according to the alternative layout mentioned in the thread. 3. Upload Tasmota, then solder the module back into the switch. The author completed this on an Appio 9605 after standard flashing failed. [#20835466]

What is the difference between the old TYWE3S pinout and the newer TYWE3S variant with swapped RX, TX, and GPIO0 pins?

The main difference is that the newer variant relocates the 3 flashing-critical pins: RX, TX, and GPIO0. The older TYWE3S follows the familiar ESP-12-compatible arrangement, while the alternate version breaks that expectation even though it keeps the same TYWE3S marking. That is why normal adapters and habits fail on the newer board. [#20835466]

Which pins stay the same and which ones move on the unusual TYWE3S module with ESP8285 under the shield?

VDD and GND stay in the same place, while RX, TX, and GPIO0 move. The author explicitly trusted only ground and power to match the old TYWE3S layout and warned that the UART is in a different location. He did not document every other GPIO because testing in Tasmota was faster. [#20835466]

What is ESP8285, and how is it different from an ESP8266 paired with an external SPI flash chip?

"ESP8285 is a WiFi microcontroller that integrates flash memory on the same chip, unlike an ESP8266 design that depends on a separate external SPI flash chip." In this thread, the alternate TYWE3S hides one ESP8285 with built-in 2MB memory under the shield, not a two-chip ESP8266-plus-flash arrangement. [#20835466]

TYWE3S vs ESP-12: how compatible are they for DIY projects and firmware flashing?

In its normal version, TYWE3S is compatible with ESP-12-style projects and flashing. The author says the standard, popular TYWE3S has ESP-12-compatible pinouts, which makes it usable for DIY work and open firmware. The exception is the alternate variant in this thread, where the pinout is mixed up despite the same TYWE3S label. [#20845841]

What is TuyaMCU, and why can it interfere with flashing a TYWE3S module in-circuit?

"TuyaMCU is a secondary controller used in some Tuya devices that can occupy the module’s UART connection, which blocks or complicates direct in-circuit flashing." The author states the alternate TYWE3S can likely still be flashed in-system, but only if the UART is not already busy, for example by TuyaMCU. [#20835466]

How can I map the GPIOs on an unknown TYWE3S module after installing Tasmota if the silkscreen has no pin labels?

Map them experimentally inside Tasmota after the module boots. The author recommends assigning 4 relays in Tasmota and then testing GPIO options one by one, because that is faster than fully tracing undocumented pads on the board. This method fits boards whose silkscreen shows no GPIO information. [#20835466]

What makes the Appio series switches noteworthy for having this alternative TYWE3S pinout?

They appear to repeat the same hidden hardware change across more than one product. The author first found the alternate TYWE3S in an Appio 9605 light switch and then noted that, from what he saw, it recurs across the whole Appio series. That makes Appio devices worth checking first when normal TYWE3S flashing fails. [#20835466]

Why would Tuya release a TYWE3S module with a different UART location when WB3S and CB3S keep the older compatible layout?

The thread does not give a reason, and the author explicitly says he does not know the motivation for the pin swap. He highlights the inconsistency: newer WB3S and CB3S modules are described as keeping the older compatible layout, including the usual UART position, while this TYWE3S variant moves the UART elsewhere. [#20835466]

What kinds of projects can I build with a standalone TYWE3S module besides using it in a WiFi light switch?

You can use a standalone TYWE3S for general ESP-style DIY builds, not only switches. The author compares it to ESP-12 and points to a clock project using ESP12 and a MAX7219 display as an example of the kind of project this class of module can support. He also notes you can buy TYWE3S as a standalone module. [#20845841]

Which other Tuya-compatible modules like TYWE2S, CB3S, and WB3S are mentioned as alternatives, and how do their pinouts compare?

The thread mentions TYWE2S, CB3S, and WB3S as related Tuya-family modules. TYWE2S is described as another ESP-based option, while CB3S and WB3S are said to be on other systems but remain more or less pin-compatible. The author also stresses that WB3S and CB3S keep layouts compatible with the older TYWE3S, unlike the swapped-pin variant here. [#20837253]

What should I check first when a TYWE3S refuses to enter flash mode or upload firmware normally?

Check whether you have the alternate TYWE3S variant before blaming the toolchain. Start with the failure fact from this thread: a standard-looking module can still have swapped RX, TX, and GPIO0, and normal flashing will fail until you rewire. If possible, confirm the shield hides one ESP8285 with built-in 2MB flash. [#20835466]
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