Downloading Tasmota Onto a Gosund WP5 or WP3 Smart Plug With Locked Firmware

How to load Tasmota onto Smart plugs when they have the new locked Tuya firmware and can no longer be flashed OTA with Tuya-convert?

I have seen a number of videos how these plugs are disassembled and in each one the method damages the plug housing.

Question 1: Is there a way to disassemble the plug without damaging its housing?

What if we could push from the inside on the back cover? Could that push the rear cover out of the plug without damaging the housing? It turns out that it is possible.

It took a screw and a couple of nails that were cut to size so that all three (3) stuck out the same amount from the front of the plug. Flat pieces instead of nails may work better, but I didn’t have any in my inventory. I then needed a round hollow shape whose inner diameter was the same size as the rim on the Smart Plug outer housing. Something that would support the outer housing, but not the back cover of the Smart Plug. A 2” to 1-1/2”PVC reducer fit those requirements.

To ensure that all three (3) pins were pushed on simultaneously a piece of steel was balanced on top of them and struck with a hammer. Since the back cover fits inside the reducer and wasn’t supported it could be driven out of the Smart Plug housing. Sometimes it took a few hits but eventually the back cover separated from the housing and the plug came apart.

As you can see there is no any visible damage on the smart plug outer housing.

Question 2: How do we reprogram this smart plug with Tasmota?

These have an ESP8266 or one of its relatives as the processors. The Tx and Rx connections are on the back of the ESP carrier board and on the bottom of the smart plug circuit board.

For the first plug I removed the board by desoldering the Line, Neutral and Ground terminals.

In then soldered wires to the Tx, Rx, 3.3V and Gnd terminals of the ESP carrier board and downloaded Tasmota onto the ESP with FlashESP8266.exe. Grounding the IO0 pin is necessary when connecting power so the board enters programming mode.

I won’t publish the details of programming the ESP. There are lots of websites and YouTube videos that show you how to do downloading Tasmota onto these types of circuit boards.

After downloading Tasmota the board was powered up and tested. Everything worked, great!

BUT, no one wants to unsolder a circuit board of a Smart Plug every time they want to replace its stock firmware with Tasmota! That leads us to the next question.

Question 3: Can we reprogram this Smart Plug without removing the circuit board?

A closer look at the circuit board reveals that there are slots in the board that provide physical separation for the Line terminal, the adjacent Neutral, Ground and low voltage circuits.

Can we use these slots to get to the Tx and Rx terminals of the ESP carrier board?

Yes, with a couple bent Dupont beardboard jumper leads.

Fortunately, the edge of the Smart Plug circuit board has a pad that allows us to provide 3.3V to the board. The shield around the ESP can be used to connect Gnd.

We now have access to the five (5) terminals [3.3V, Gnd, Tx, Rx and IO0] necessary for reprogramming the Smart Plug without de-soldering its circuit board from the Line, Neutral and Ground terminals.

It did take a bit of trial and error to adjust the bent Dupot beardboard leads so that they are connected to the Tx and Rx solder points of the ESP carrier circuit board.

Grounding the IO0 point when powering up the circuit board also takes some practice. An indication that you have grounded to pin is when the onboard led DOES NOT flash continuously. Flashing means it's waiting to be paired, meaning that the firmware is running on the ESP. No flashing means it's awaiting a firmware upload.

With practice, after 3 or 4 attends the Smart Plug is reprogrammed.

I’m sure someone will be able to fabricate something where the leads or connectors are more accurately positioned and easier to connect to the TX and Rx terminals of the ESP carrier board. In the interim this is my method for reprogramming these Gosund WP5 and WP3 Smart Plugs with Tasmota software. All pictures in this instructable were taken with WP5 plugs. The WP3's have the same layout.

Hopefully it provides some useful information for others and generates some thoughts for other projects. Thank you everyone who has contributed to Tasmota, Tuya-connect, various forums and Instructables.