Raspberry Pi lapdock hackstation

[Brent Burton]

Motorola has provided "lapdocks" for some of their smartphones since 2011. When mounted, the phone reboots into a more desktop-oriented operating system. However, the desktop environment is very limited and not compelling, so these aren't selling at their $500 original price.

At their core they are a USB hub with 2 USB ports, touchpad, keyboard, and HDMI screen in a very thin form factor wrapped in magnesium alloy. They are now going for about $50 on ebay and elsewhere. The dock itself is a nice piece of hardware, and the internal battery will run a R-Pi for quite a while.

A buddy brought his into work today, and I snapped some pictures of adapters necessary to plug a raspberry pi into it. You need a male-to-male USB adapter, and a female-female micro HDMI adapter.  I don't have links to the adapters, but they are from Hong Kong vendors. The keyboard and touchpad work fine, and audio works, too.

This "Daily Steals" website has brand new lapdocks for $49, designed for the Motorola Droid Bionic.

http://www.dailysteals.com/ then hover over "Today's Steal", and it's listed there.

The catch is this particular deal ends at 11pm CST.

Sorry I couldn't send this sooner.

 -Brent

[Jon Kelly]

Thanks for posting this! I've been (half heartedly) looking for a deal on these so I can try and hack my phone to it. Knowing that it works with a raspberry pi makes it even more awesome.

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Regards,

Jonathan Kelly

Executive Director - ATX Hackerspace

www.atxhackerspace.org

9701 Dessau Road, Suite #304

Austin, TX 78754

[Brent Burton]

Wow, the motherlode of lapdock hacks:

http://www.robpol86.com/index.php/Atrix_Lapdock_Other_Uses

PROTIP: the above page has links to Deal Extreme and Ebay offers for the various adapters.

[Alex Morales]

Thanks!  Nice find.

[Danny Miller]

I have one of these on my Raspberry Pi.  It's cute!
Sound and everything.  And the whole thing is a large battery that can power the Pi, too.

One downside I noted was the mousepad buttons were really hard to press.  They still had snap-action feel and all, they seemed to be working as designed, yet still sucked.  It couldn't really be used on your lap, the force to click it would push the whole lapdock around.

The connectors are mechanically... "awkward".  Micro HDMI and mini USB MALE stubs sticking out of the lapdock, and the HDMI cable has a female-female adapter because there's no micro HDMI cables ending in female.  This adds a long, rigid mass stuck on the stub and it tends to fall off, kinda tears up the micro connector too.  It's sure be nice to build and solder on a more mechanically sound interface but that'd be a trick with the HDMI cable, it has 19 pins, tiny wires, and some are sensitive to delays/reflections and thus splicing may cause problems.

Danny

[Eric C Blount]

I just ordered one. They're now in the Everything Must Go section, for $49 and free shipping:
http://mobile.dailysteals.com/heist/5695/Motorola-Lapdock-100

I've been wanting one of these for a while, as I have the Droid Bionic. The possibility of using it for a Raspberry PI pushed it into must-have territory.

Thanks for sending this!

Eric

[Danny Miller]

BTW, basic architecture here is:
The lapdock is an HDMI monitor/speakers
It is a powered USB hub with the keyboard, mousepad, and the USB ports all attached to the hub.  The hub input is the MALE mini USB-out stub intended to plug into the phone.  But IIRC the output stub is unusual in that it proves power OUT to the phone through it. 

There is a large battery inside the lapdock, and the USB-input ports in back are of course powered.  However, these do power down when the lid is closed, so the Pi would have to reboot.

Danny

[Brent Burton]

My coworker and I have the most recent R-Pi (rev2) and one of the changes they made altered how the USB ports were connected to the USB controller chip. The short of it is, we can power the R-Pi through the USB A ports, and don't have to have power to the micro USB port on the R-Pi.

Do you power yours the same way, Danny?

[Brent Burton]

Hey, this is different that what I ordered.

This one, the lapdock 100, has a cable that connects to the phone. This would be better than having a rigid connector for the cable adapters as Danny mentioned.

[Martin Bogomolni]

okay, in for one.. this is just too good a deal to pass up for a rasPI controller for the Replicator.

-M

[Danny Miller]

That looks like a phone-specific cable, not HDMI/USB.

That's trouble, because it's impractical to splice HDMI.  USB, yes.  HDMI is just too many tiny delay-sensitive wires.

Danny

[Brent Burton]

It's still compatible with the droid so it must have the same USB/HDMI connectors.

[Danny Miller]

I think the change isn't the controller chip, rather, the original design had polyfuses between the peripheral USB connector's 5v pins and the main 5v power bus, which is tied directly to the micro-USB "power in".  The polyfuse caused voltage drop problems on the USB peripherals and they soon recommended it be removed. 

That effect is no problem for the lapdock, as it is self-powered.

The micro-USB power-in of the Pi IS itself a problem, because all the micro-USB cables I've examined have a surprisingly high resistance, in the tens of ohms.  This will cause substantial voltage drops under load.  The micro-USB power-in is not a USB peripheral, it is only for power, and it doesn't work as well as it should because of this.

So you can power the Pi "backwards" through the USB Type A peripheral connector, yes.  However, the other end must still go through the micro-USB male stub on the lapdock, because that's the USB-host input to the hub inside the dock.

The problem of note is that you're still going through one micro-USB connector, and I suspect any cable with a micro-USB on one end is likely to use thin, high-resistance wire inside, thus retaining some of the impedance issues.

Danny

[Brent Burton]

At least three of us have received our lapdocks now. Here are the cables and adapters I am combining:

I opted for female cables at the lapdock's connectors, and adapters between the RasPi and cables.

Cables from Ebay:

USB:  http://www.ebay.com/itm/270798436083

HDMI:  http://www.ebay.com/itm/261147590696

Adapters from deal extreme:

USB:  http://dx.com/p/usb-male-to-male-adapters-pair-106343

HDMI:  http://dx.com/p/hdmi-male-to-micro-hdmi-female-adapter-66079

These parts are coming straight from China (Hong Kong and Shanghai), and I received the first cable today (ordered ~10 days ago). These are odd endpoints and I'm not sure they are part of the respective specs, like the female micro HDMI to male HDMI...

Martin, I like how your lapdock has the separate cable with the connectors on it. That is a little more flexible than how my dock is made.

[Martin Bogomolni]

Good news everybody!

http://www.all4cellular.com/product/motorola-atrix-4g-upgrade-kit.html

This kit is on sale for $17.95. Female->Male micro HDMI, and
Female->Make micro USB. The microUSB to USB-A adapter is available
at Discount Electronics and Frys :)

-M

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[Brent Burton]

That's a nice package. You still need the micro HDMI to normal HDMI adapter. Have you found that stateside?

[Martin Bogomolni]

Absolutely! In fact, those are available at any Discount Electronics
store. They sell the standard->Micro HDMI adapter dongle for $12, and
they also sell a standard->micro USB adapter dongle for $9.

-M

[Shadow]

Monoprice also has micro HDMI to standard HDMI cables also.  For the 1.5 ft version, it costs me $6.32 total including the shipping.  That's where I got mine.

[Martin Bogomolni]

Oh, yeah, they also have that cable at Discount Electronics .. slight
markup ($9 vs $6) but convenient to get. Discount Electronics stocks
a lot of Monoprice cables.

=M

[Brent Burton]

I received the HDMI cable today, and to test it I connected a tablet to the lapdock, but it wouldn't power on.

I tested the new HDMI cable between the tablet and my TV, and it worked OK for that. Looking at the various links I sent out earlier in this thread, it sounds like my HDMI cable doesn't implement all the lines, specifically the DDC/CEC line the lapdocks use to sense a connection.

It's a crapshoot whether a particular cable includes this line or not.

Tomorrow I'll try another adapter+cable to confirm this.

DDC/CEC info:

http://www.element14.com/community/groups/raspberry-pi/blog/2012/09/27/raspberry-pi-lapdock-hdmi-cable-work-around

[Brent Burton]

The cable was the culprit. I used a different HDMI cable with my friends female micro HDMI to female micro HDMI adapter and it works fine.

My ras-pi lap dock has been running for two hours and 4/5 battery lights are still lit. It's been idle but running X.

[MutantGarage]

Did you get the HDMI Micro F-F adapter locally?

Discount only had a Micro-M to HDMI-F cable, nothing that plugged into the RPi HDMI cable.

Does Frys have them?

Anyone gotten the All4Cellular cables to work, still needs a HDMI Micro-M to HDMI-F adapter that carries all the correct signals.

[Martin Bogomolni]

I think I bought the last micro-f adapter at the 183 north discount electronics location

[Brent Burton]

No, the micro HDMI f-f was ordered off eBay.

Attached is a pic of the setup tonight that works.
Top right is lap dock power (charging).
Top center is the USB micro female to normal female.
The USB male-male adapter joins it to the raspi.

Back at the top is the unconnected HDMI male, the f-f adapter, and a higher quality micro HDMI to normal HDMI cable (from a Motorola tablet).

There is also a USB WiFi adapter plugged into the lapdock's rear USB port.

This setup ran for over six hours nonstop today and the screen looks great.

One of my earlier emails listed my original parts list but included the other HDMI cable that's turned out not to work. I apologize if anyone ordered that combo; thus is the nature of hacking.

I happened by Discount Electronics today and saw the adapter Martin showed. The issue is you need the lapdock's micro USB connected to the raspi's large USB port. That provides power and connects the lapdock's hub to the raspi. That Y cable still needs other adapters.

Brent

[Denzuko]

Thanks Brent for posting this. I've been working on a RasPi Server Farm and Thin client cluster for a few months now and this is the perfect thing I need to finish a few of the Client clusters.