Accidentally flashed Sonoff Mini with tasmota-minimal.bin. How can I recover the device?

[Frank Kintrup]

Hi all,

I've accidentally used the wrong firmware tasmota-minimal.bin to OTA flash a Sonoff Mini DIY.
Now the device appears to be dead. The on-board LED is off, the device creates no WiFi to connect to and also does not react to the button on board (no clicking of the relay).
Is there any way to recover the device or is it completely bricked?

I've tried to recover with two steps found in the FAQ.
First, holding down the button for 40 seconds and then power cycle the device (no success) and then the described "Fast Power Cycle Device Recovery" (cycling power 4 times, no success either).

Is there any other way to recover the Mini?
Or do I need to flash it again using an FTDI board?
Will this even work?

These lead points on the Sonoff Mini board to solder the cables to are sooooo damn tiny... :-(

[Ing. Umberto Ballestrazzi]

I use minimal on mini few weeks ago to flash the latest bin > 512kb and I had no problem with minimal.

Have you tried to do the same things explained on faq after removing the diy jumper?

I don't know what the diy jumper does...

If you can't find another solution you can use ftdi.

You can see that it works at the end of this video...

https://youtu.be/9fkYBWvwn4A

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[Michael Ingraham]

If you use minimal as the binary that you OTA flash using the DIY method then you don;t get an means to set the Wi-Fi credentials... so you are stuck. You can use minimal only after an initial flash and configuration of Tasmota.

So, in your case, to recover, you will have to solder some leads on the Mini PCB and use serial flashing to get a full version of Tasmota in the Mini.

Mike

[Matheus Klanert]

I did the same mistake and I didn't want to solder anything because the Sonoff mini has such small pads and my soldering skills are most likely none...

So after like 5 hours working on that I figured my way out, and the solution is

- Look for a hidden network and/or with a weird SSID and connect to it with your PC. To check if it is Tasmota's AP by turning the device off and on and check if that weird wifi disappears and shows again.

- If you do not have cURL, install it. Win10 already has it as default (most versions, at least)

- On command prompt, execute the following command

curl -F "u2=@disk:/path/to/file.bin" http://192.168.4.1/u2

You should get a long status back and now you can find your device as a usual access point and proceed with the usual Tasmota's setup.

That is it.

Now, if you want to learn how I got there:

- you should not use tasmota-minimal for first time flashing tasmota OTA - ok, we already learned that (painfully). Actually, I thought I had it flashed with tasmota-wifiman.bin, but not so sure now...

- for me, wifi was showing up as a "hidden wifi" with a weird SSID. I knew it was tasmota's because when I unplugged sonoff, it disappeared

- however, I knew the webserver still was there and still could do an upgrade, because that is what tasmota minimal is for. It just doesn't show the webpage because it cannot resolve IP (I honestly don't know the technical term for that)

- so i reached the webserver from another tasmota device I had and noticed that the OTA file upgrade form triggers an action "u2", with the file field name also being "u2".

- all that was left was to build the curl command. Basically it is like:

curl -F "<formFieldName>=@<full path to file>" http://<device ip>/<form action>

I'm glad I didn't need to solder anything.

Matheus

[Michael Ingraham]

Brilliant!

You may want to consider adding this information to the Sonoff Mini Tasmota docs article.

Cheers!

Mike

[Stephen Mann]

On Sunday, December 8, 2019 at 3:43:47 PM UTC-5, Michael Ingraham wrote:

So, in your case, to recover, you will have to solder some leads on the Mini PCB and use serial flashing to get a full version of Tasmota in the Mini.

Mike

I made a programming jig to program my Mini's using my normal tool, Tasmotizer:

Parts:

Pogo Pins:

https://www.amazon.com/dp/B01913L0UK?psc=1&ref=ppx_pop_dt_b_asin_title

Thingverse Programming Jig:

https://www.thingiverse.com/thing:3767667

I soldered a short wire to each of the four Pogo pins, about 3cm from the bottom, then used hot glue to hold the pieces as I built it.  The header pins are arranged the same as the Sonoff Basic and I just use the same UART assembly that I program the Basic's with.

I don't have a 3D printer, but this guy (ball...@gmail.com) made the parts for me for $10 including shipping.