Sunday 28 March 2021

How to Flash Tasmota onto a Arlec Grid Connect Smart Plug-In Socket PC190HA from Bunnings



The Arlec PC190HA is a cost effective smart socket that is Tasmota compatible. The socket uses the TYWE2S module based upon the ESP8266.

This socket can be purchased from Bunnings individually for $17.50 or in a 4 pack for $60.

Downside of this unit, is Arlec have introduced Tri-Groove Security screws, which is rather uncommon and does make opening this unit a little more difficult, but not impossible. More about this later.

Tri-Groove Security Screw

Replacing the firmware

Arlec like many other manufactures have updated the Tuya firmware. Frustratingly this means the OTA update method via Tuya-Convert is no longer an option. Efforts are still ongoing to fix this, but there is no ETA.

The alternative is to flash via serial using a USB to TTL Serial Converter and Tasmotizer (Windows).

HW-417 USB to TTL Serial Converter

Opening the PC190HA

To get access the TYWES2 requires opening the socket. At this point I remind readers;

Proceed at your own risk. This information is provided as a guide and you take full responsibility for any harm or damage that may result. Opening any mains powered device should only be done by a professional. I accept no responsibility for any malfunctioning devices as a result for this tutorial. This process will void warranty of the device. Proceed at your own risk.

With that out of the way opening the PC190HA will require a Tri-Groove screwdriver or similar.

Make your own Tri-groove screwdriver

As I couldn't find a local supplier, I opted to fashion my own from a spare Allen key (~4mm or 1/8") and a common triangular file.

Process isn't as difficult as it seems and even a rough tool will be sufficient to remove the screws. Below was my first attempt and I was successful in removing the screws. 

To fashion the Tri-Groove tool, place the Allen key into a vice and simply file a V from the middle of every second flat side. Position the file at a ~45 degree angle.

With any luck the tool will be sufficient to remove the screws. The top case is secured by three lugs which can be overcome by hand.


The PC190HA uses the common TYWE2S module and is relatively easy to get access to the serial port pads. The rear cover will need to be removed to expose the IO0 pad on the TYWE2S. Remove the single Philips screw in the centre of the PCB.

Solder on jumper wires.

To successfully flash the TYWE2S the USB TTL converter needs to be connected supplying 3.3v. Also  IO0 needs to be pulled to ground, at initial power on only.

Make sure your USB TTL converter is set to supply 3.3v, not 5v.

The approach I used was to split off an additional ground wire and hold it on the IO0 pad, while connecting the USB TTL converter.

Open Tasmotizer, Select the USB port.

Select Release and optionally backup original firmware.
Note: you can preload the WiFi and other configuration detail if you so choose.

Click Tasmotize!

If flashing was successful, unsolder the jumper wires and reassemble. I opted to keep the Tri-Groove screws, but you can replace with similar Philips head screws if needed.


By Default Tasmota will present as an AP. My preferred option is to use a phone to connect and configure the WiFi. Once it is connected to your WiFi use Fing (Android app) to locate the device IP and connect to the web interface at

Arlec PC190HA Tasmota configuration

Refer to the Tasmota Devices database at

Template: {"NAME":"Arlec-PC190HA","GPIO":[0,0,0,0,320,0,0,0,224,576,32,0,0,0],"FLAG":0,"BASE":18}


  1. Hi. I tried to use tuya convert ota on a new purchase of these plugs. The older ones worked fine, but it appears that they have since patched the vulnerability that allowed ota flashing.

    I came across this page and decided to have a crack at opening one up and flashing with a hard connection. It was the securing screws that had me stumped but with a slight modification to the method I was able to open the unit and gain access to the inner-workings. After unsuccessfully trying to file an Allen key to shape it dawned on me that the very thin metal cutting blades that you can get for angle grinders these days, might just do the trick. So, that's what I did. I cut a slot in every second side of the Allen Key, using the angle grinder. It was very quick, very accurate and worked like a charm. Took all of 3 minutes to make the security screw tool.

    One thing I did find was that the template did not work for me. I had another template that I had used to flash the earlier models and it worked fine.

    So, one plug down, 7 to go...

    1. Thanks for the post Russ. Good idea in the cutting blade. Probably could use a Dremel to fashion the tool too. When I tried the file method I didn't think it would work, but as you found, anything that can get a bit of purchase on those screws will remove them. They're not that tight.

      I too had some issues with the template initially, but it turned out I missed a step. The quoted template (not mine) works on the HW I had.

      PP below reported the same issue, so there might be a couple of revisions of HW.

      Can you post your template?

  2. This comment has been removed by the author.

  3. 4mm Allen key and angle grinder then a bit of finesse with a file did the trick for me. Nice big solder points on this one too.
    Worked a charm!
    Good source for templates here

  4. The current blackadder template didn't work for me. I had to us that of the older version, Arlec Smart PC189HA Plug.
    {"NAME":"Arlec Single","GPIO":[0,0,0,0,57,0,0,0,21,0,90,0,0],"FLAG":0,"BASE":18}

  5. Thanks PP.

    Current template I'm using is below and above and I confirm works. I didn't create the template. Possibly there is two hardware revisions.


    GPIO4 = Led_i = 1
    GPIO12 = Relay = 1
    GPIO13 = LedLink_i
    GPIO14 = Button 1

  6. I have the iFixit Pro toolkit with a size 6 spanner head which I was able to use to get the screws out. Just go slow and easy and don't stress the single point that's turning the screw.

    1. Got a link to this kit?

    2. This comment has been removed by the author.

    3. I have a "Protech 73-In-1 Screwdriver Kit" that I purchased from Jaycar a while ago. this thing is a godsend and contains all the strange bits you'd ever need. Contains the weird pentalobe bits for opening up apple stuff and of course contains multiple different versions of the triangular bit required to open this Arlec Grid. The kit contains so many weird bits. I carry with me all the time. cheers

    4. followup comment - the Arlec Grid plug i am opening now contains different screws to what you showed. it has a triangular head screw which my kit has a bit for. i don't believe i have a bit that would get out the screw you showed.

    5. Sounds like a TA bit. Might have to check next time I'm in Bunnings. Where did you source these plugs? Multipack?

    6. Yes it does appear to be a TA bit. The exact product I was working on was the DETA Smart Rewireable Plug model number 6930HA. There is a plastic clip at the top of the plug which was near impossible to unclip - i ended up snapping it, not that it really mattered much.

      I think next time I'll use the 6000HA inline switch as it's much easier to open up and it's only a few dollars more.

  7. Indeed I do. I personally recommend these toolkits and iFixit. A bunch of people who really care about right to repair too. They've got amazing content on how to fix your own stuff.

    1. Cheers for that. Will check them out.

      I was just looking for the selected bits, as I have picked up most of the others already.

      Do those kits have the tri-wing ?

  8. Correction these kits don't actually have the Tri-Groove. These seem to be hard to come by.