Mi Wifi Router 3 / MIR3 Hardbrick SPI Flash Mod

Hello everybody!

I'm trying to bring my router back to life after a wrong Bootloader installation, and by installing an easily-programmable SPI flash module , by way of the SOIC-8 sized pad.

I have checked that to boot the router from an installed SPI flash chip, two modifications need to be performed, but I don't know how it should be done.

  • Short with a solder bridge, R139 to the adjacent R137 pads.
  • Short with a solder bridge, R124 to the adjacent R126 pads.

Three ways to do it come to my mind:

Hi,
I have the same problem, but warning! All connection you show are wrong! You can damege device!
As well as described in wiki page, by factory R139 set the TXD2 signal to 0 (it's connect to ground or negative) and R124 set the GPIO0 signal to 1 (it's connect to positive).
R137 and R126 are missing.
To boot the router by SPI Flash needs change setting. Needs to set TXD2 to 1 and GPIO0 to 0.
The schematic seems to be this:
Spi Mod
So, to do this there are two way:

  1. Remove R139 and R124, and solders new resistors at R137 and R126.
    But this way, because the components are micro, it's too hard expecially if you hasn't pratice whit soldering iron.
  2. Solder a bridge at R137 and R126. I this mode you connect directely to power pole (respectively positive and negative) to the TXD2 and GPIO0 signals.

But, checking the circuit board, Xiaomi seems to help us carring TXD2 and GPIO0 signals respectively to J91 and J90 connector.
So, you can simply solder a juper on the hole and connect they by a wire as showing in the picture:
Spi Mod 2
BE WARE, this method connect directly the power. An accidental shot circuit can be permanentely damege the device.
Teorically it should be correct but, after solder and programmed with the MiWifi Mini Firmware a W25Q128FV SPI Flash, ins't work!
I tried various FW, but nothing works.
I hope to someone can help us.!

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Thanks Deotim to share this.
Yes... it can work, but, to boot from SPI, it's needed to remove resistor R139 using a soldering iron or pull also TXD2 to positive voltage.
Probably it may be sufficient to use, even in this case, an 1Ko resistor as picture.
Spi Mod_SPI Boot
I can able to program directely on board the SPI Flash trought a cheap CH341A programmer and an SOP8 clip, but the real problem is than I haven't a XIAOMI MINI FULL DUMP and every link on 4pda forum is broken.
I isn't able to make any full firmware.
So, is there anyone who can share the Xiaomi Mini Full Dump image?
Thank You.

Xiaomi Router 3 - https://drive.google.com/file/d/1OCh1IR5yFdX8ZdGU-jzJnbGeiDMiJIpI/view?usp=sharing

Xiaomi Router Mini - https://drive.google.com/file/d/1MRqULGXoDJ_ZBfbTzQ2Kd0Y5HM04PHm5/view?usp=sharing

Yesss!!! Blue light is back!
Thanks Deoptim!
I downloaded your zip file and I thought than image to program was "mtd0.bin", so I sent it to SPI Flash and after I power on the router and now I have an MiWifi Router Mini.
So now I ask myself: can I have access to NAND Flash and recover it?
I'll work around...

Hi, what did you do in the end to boot from SPI? You used two 1K resistors on J90 and J91 and nothing else? Thanks

Yes, I use 1Ko resistors bridging J90 and J91as show in latest picture but I have already removed 4,7 Ko SMD resistors I don't known if can work with resitors.
If you wan't remove R139 and R124, you can try to reduce 1ko resistors to 470 ohm.
Bye.