Adding serial/UART support to TL-MR3020

intro

In case you accidentally bricked your device while trying out the Evil-AP and need a root shell to fix it or wish to add support just because, here’s how to do it. Alright, for this to work you’ll need a USB UART adapter (usually CP2102 based) and its pinout. On top of this you’ll need some male and female pin headers (2.54 mm), a soldering station, screwdrivers, tweezer, wire snipper, wire, solder, glue and an instrument file.

allthestuff

First carefully open up the case. Due to the glue it’s not easy to do without making marks in the case, so be warned that you might scratch it somehow. Once that’s done lift the board out. The three pins that need to be connected are GN, RX, TX, skip the last one.

board

We’ll open up a hole in the case close to the UART header to allow a cableless solution. Here’s PoC of the board with added headers.

poc

To create this hole use the soldering iron to heat up the plastic and apply some pressure. Once the hole appears stop and instead use a small instrument file to shape the hole correctly. Make sure to keep the size of the hole in a shape that’s not too big since that might create issues for you. Place the female pin header into the created slot.

meltmelt2

Now clean the chassi from any plastic dust and then put the board back. Here’s how it should look so far.

pinchole

The next step is to solder the pin headers.  First solder the male pin header onto the board (not when the board is in the case).

soldermale

Now make sure the male and female pin headers connect as they should and if you want you can perform a test that it works.

testuart

Solder the male and female pin headers together and apply some glue to the female pin header so it stays put.

finalsolder

To be able to close the chassi again you might need to snap a little bit off the hook on the chassi.

final

This is not the most pretty solution, having to both place the dongle upside down and also very little reach. So, let’s add a cable to the USB UART adapter! For this we’ll need some cable with at least three wires, a male and a female pin header. Lucky enough the cable used here only contain three conductors. These three wires are soldered onto the female pin header.

fem1 fem2

Other part of the cable is soldered onto the male pin header.

malehead

The cable is essentially complete, but to add some protection let’s add some glue onto it and then a heat shrink if you want. Then obviously do the same on the other side of the cable.

glue1heat

Mark the polarity of the cables some how to ensure correct insertion and then you’re done. Here’s the final result!

final2