Using a Motorola Atrix Lapdock as a HDMI Monitor and USB Keyboard / Mouse

A coworker of mine briefly had a Motorola Atrix 4G about a year ago, along with the “lapdock” accessory that turned it into more of a “full fledged” laptop or netbook with a regular Firefox web browser and a more desktop-like environment. I got to play with the setup for a bit, and thought it was a great idea, but with flawed execution (especially at the initial $400+ price for the lapdock alone).

About three weeks ago, I ran across the lapdocks being sold very cheaply through 1SaleADay. After some research, I ordered four of them, then ordered various cables and adapters from a couple of different online vendors after figuring out what I needed. The last part of my orders finally arrived tonight, and I’m glad to say that my idea was a success.

First, I have to give credit to this XDA-Developers thread for the idea. The ports on the Lapdock are really nothing more than a male Micro-HDMI and a male Micro-USB, in the right layout to plug directly into the ports on the Atrix. The only other ports are two normal female USB ports (for thumb drives, etc) and the power jack for the AC-to-DC wall wart.

Here’s the adapters and cables I ordered:

Micro HDMI socket Female to HDMI Male adapter convertor, $4.64
Generic Hdmi Coupler (Female To Female), $1.51
Normal HDMI Male-to-Male cable, I had one already, they can be found for $1-2

USB Mini-B Male to Micro-B Female Extension cable, $8.85
USB Gender Changer – A Male/Mini-B Female, $5.00
USB 2.0 Extension Cable – Black, $2.92

First, I had to trim down the plastic molding around the Micro HDMI adapter so that it would fit down on the male Micro HDMI plug in the fold-out “tray” on the Lapdock. For this first one I just used my pocket knife, but now that I know what’s needed, I’ll use a Dremel tool for the other three. The lapdock won’t work without a HDMI video signal, so once the adapter fit properly on the plug, I hooked up the power, plugged a HDMI female-to-female coupler on the adapter, and then connected the lapdock to the HDMI video out on a Windows system.

(6/14/12 update: The Atrix 4G Upgrade Kit consists of short male-to-female MicroUSB and MicroHDMI extension cables that prevent having to physically modify any adapter plugs, but I’ve not found a source for it that doesn’t charge at least $30!)

Here’s what the adapter, coupler, and cable looks like when plugged in:

And here’s the result! My system saw it as a second monitor, and I was able to use the normal keyboard and mouse to drag a browser onto that screen.

Getting the USB cable (using the Micro-B-Female-to-Mini-B-Male cable, plugged into a Mini-B-Female-to-A-Male gender changer, then to a normal USB A-type extension cable) to fit next to the HDMI plug required a bit more shaving and trimming down of the plastic molding around both plugs. I finally got both to where they would fit without blocking each other.

NOTE: I stripped the insulation off a portion of the USB extension cable and *cut the red wire*. That wire/pin carries +5 volts, and is normally used to charge the Atrix phone from the lapdock. Since we only want to use the keyboard and trackpad as input devices, we don’t want to feed +5V back into the USB port we plug into. So, I cut the red wire and re-insulated that part of the extension cable with some silicone tape.

I plugged the other end of the USB cable into a spare port on my PC. Windows 7 detected the keyboard and mouse, installed some drivers, and bingo! I was able to use the keyboard and trackpad on the lapdock itself to drag a browser window onto the “second monitor” that was the lapdock’s LCD screen, and type normally to pull up a web page.

I’m happy with the results so far; the hard part is done. These lapdocks will be used as consoles for systems where I don’t want to “waste” a full LCD monitor and keyboard on a rarely-used console. My next experiment will be trying out a VGA-to-HDMI adapter box that I bought for $30 off Amazon, to see if I can make one of these work with my USB-and-VGA KVM unit.

These will also work wonderfully with my Beagleboard, BeagleBone w/HDMI add-on, or the Raspberry Pi boards if mine finally ship at the end of this month.