Topic: Converting MicroB USB to USB2serial+Power on TP-WR703N
As you know TP-LINK TL-WR703N have MicroB USB port used ONLY for supplying power to the router. There is USB-A to USB micro-B Cable in the box and USB Power Supply.
I got mine a few days ago, but I did not know that it's possible to use OpenWRT firmware on it.
Using OpenWRT gives you endless opportunities to play with that device beyond router abilities...
My first idea was to add LiIon buid-in battery for field use + mini charger, but this is not what I need right now, so I decide to implant my USB2Serial converter (based on PL-2303HX) inside Router box and re-use free ( and not used) D+ D- connections on Micro-B USB port. This will save me one cable and will make the ongoing testing more fun. The other toughs that now I'm having is adding external antenna and dedicated power-jack, plus 1-Wire sensor, and one or more relay to some of really difficult to solder GPIO.
First I need to modify my USB2Serial converter because it was designed for 5V TX levels, this chip PL-2303HX has internal 3.3v voltage stabilization, so I just needed to make sure that the TX not exceeding 3.3v to not fry my AR9331 chip. (Mine is in SSOP 28 package, PIN#4 is VDD_232 for defining RxTx levels it was connected to 5V so I redo and re-connect PIN#4 to PIN#17 VDD_3V3 using thin coper wires) A few more tweaks, getting off USB-A connector on the board and Pins to be able to fit it in the tiny router box, also moving 12MHz crystal to back side of the board.
How it was before(fixed): http://dl.dropbox.com/u/12258575/TP-LIN … 21_004.jpg
How it's now: http://dl.dropbox.com/u/12258575/TP-LIN … 22_023.jpg
WR703N board up side: http://dl.dropbox.com/u/12258575/TP-LIN … 21_001.jpg
WR703N board bottom side: http://dl.dropbox.com/u/12258575/TP-LIN … 21_002.jpg
With USB2Serial side-up: http://dl.dropbox.com/u/12258575/TP-LIN … 22_002.jpg
TP_IN,TP_OUT solder joint view closeup: http://dl.dropbox.com/u/12258575/TP-LIN … 22_006.jpg
Back in the box: http://dl.dropbox.com/u/12258575/TP-LIN … 22_026.jpg
Cover on: http://dl.dropbox.com/u/12258575/TP-LIN … 22_030.jpg
I post this quick and dirty hardware hack, with hope that someone will find it useful.
For most connection I used coper coil wire ( it has lacquer isolation, which is easily burned with soldering iron, no need to be cleaned), and most important do not apply much pressure on the tiny TP_IN and TP_OUT soldering joint.
I just discovered the power of OpenWRT, so I'm new here.
Oh I forgot minicom console shoot: http://dl.dropbox.com/u/12258575/TP-LIN … 2303HX.png
I'm on Mac and I have to install minicom and PL-2303 driver (md_PL2303_MacOSX10.6_dmg_v1.4.0.zip) before been able to log into the serial terminal.
My TL-WR703N is ver.1.5, PCB rev.1.1