Bargain

Thanks Keith. I bought a couple, and ground an old screwdriver to the required triangular point to undo the screws. The device is indeed a TUYA TYWE2S, which is based on the ESP8285, which is an ESP8266 with

1MByte of flash on-chip, so it doesn't need external flash like the ESP8266.

These can be re-flashed "over the air", and until Tuya started rolling out a patch in Jan, you could do it yourself using "

". So if that patch has been applied by Aldi/Medion (which is unlikely but possible), or if Tuya has reflashed your device over the air, the only way to reprogram it is to reflash using an RS232 dongle.

The device is supported by the Espurna open source smart-home software available at , which uses Arduino and PlatformIO, so even script kiddies have a chance of making it go. Adafruit sell modules with the same chip, so it should be well supported: .

I haven't yet diagnosed which of the 9 pins are connected to what. But there's obviously 3v3, GND, Tx, Rx and RESET. So that leaves four connections, of which one goes to a momentary push-button and one must drive the relay, leaving two... spare? I don't know yet.

In any case, unless you want to give some unknown Chinese people access to your WiFi network, I'd recommend you don't buy these... unless you intend to reflash them with some new code.

Clifford Heath.

I am lead to believe that the relay is on GPIO 14 although I haven't personally confirmed that. There is another connection to the energy monitoring chip, one to the push button and one to the LED.

Word has it that flashing them with Tasmota and the Teckin module will work.

Here is what I have traced out:

• IO13 goes to the LED, active low

• The switch goes to RXD0, with resistor pullup and debounce cap

• IO14 drives the relay via a transistor (which pulls low)

• IO12,IO4 and IO5 go to the energy monitoring chip

• TXD0 and TOUT are not connected

To re-program it, it would be necessary to free up Rx from the debounce capacitor. It would probably suffice to add a series 2K resistor, so the button still works but RS232 can over-ride that.

Thanks.

Does anyone recognise this energy monitoring chip? The marking I see is "1852AVH":

Clifford Heath.

I eventually got around to doing something with these. I flashed them with tuya-convert using a raspberry-pi. I then updated them to the latest version of Tasmota, and applied the Medion template available on the main Tasmota site. I still have to set up MQTT, but though the web interface I can control power on and off and monitor the voltage current and power (some calibration was needed). The power can also be toggled with the button on the switch itself.

Some of the steps weren't totally straight forward but the biggest problem was that Tasmota has a maximum WiFi password size of 31 char, I had an over the top Wifi password of 63 char and had to reset the password on the router, 3 laptops, 2 iPads, 2 phones, 3 raspberry-pis and 2 set top boxes.

I'm pretty happy with the result.