Raspberry Pi Lapdock HDMI cable work-around

RE: Raspberry Pi Lapdock HDMI cable work-around

alexose — Sun, 15 Mar 2020 17:35:49 GMT

If you don't want to tear open your Lapdock, I can personnaly vouch for the DIY HDMI cables from Adafruit. They actually include all 19 wires and work properly with the Pi. You'll need the following parts:

https://www.adafruit.com/product/3561

https://www.adafruit.com/product/3559

https://www.adafruit.com/product/3556 (or Mini or Standard depending on your Raspberry Pi model).

These parts are also available via eBay for cheaper, but they ship from China.

Unfortunately the PCB is somewhat wide, so you'll need a very slim micro USB cable to go with it. I used a dremel to shave down my cable so it would fit. You could also probably make your own cable from one of these connectors: https://www.adafruit.com/product/4023 .

(I'm cross-posting this response several places because getting to the bottom of this issue took me several days and at least $60 worth of cables and converters. Hoping that I save someone else the headache!)

RE: Raspberry Pi Lapdock HDMI cable work-around

jemenake — Sun, 26 Oct 2014 17:15:18 GMT

So, I'm having a confusing problem with trying to using a LapDock with a RasPi: the keyboard and trackpad don't work. But I don't think it's an issue with the data wires, I think it might be something odd happening in the LapDock, itself.

Almost all of the HOWTO's for LapDock/RasPi interconnect I've seen use the LapDock to power the RasPi, making a Frankenstein laptop, in a way. That is not my application. I've got some RasPi's embedded in the field. What I'm trying to make is a portable KVM where I can go out to a location, plug in my LapDock and have a console whereby I can work on the RasPi. In other words, it is to save me from having to lug an LCD monitor and USB keyboard out to the location and then find a place to plug in the monitor.

The crucial bit to understand is that the RasPi is already powered via its micro-USB port before I come along with the LapDock. When I connect things up, the HDMI connection works fine, the RasPi just never sees the LapDock's keyboard or trackpad. I know the USB ports on the RasPi work because I can plug any other USB keyboard into it. I also have tried plugging the USB line from the LapDock into a regular PC, and that does not work. So, something about the LapDock's USB data is failing to get to the RasPi. My suspicion, thus far, is that the LapDock doesn't activate it's keyboard/trackpad unless it sees something draining power from the USB port (as this is how it would sense that you've got your phone docked in it). For people powering their RasPi from the LapDock, there is power being taken from the USB port, so this could explain why nobody else is having the issue.

Does anybody know if the LapDock behaves this way? Is the data from the USB port deactivated if there is no load on the power wires?

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Thu, 20 Mar 2014 20:58:27 GMT

[View:/resized-image/__size/335x240/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-37353cbe-2b14-45b9-b195-070bc97196cf/contentimage_5F00_190384.jpg:335:240]

Hello All lapdock moders.

I have spent some time investigating the lapdock connection in order to create the above direct connect cable.

The challenge has been testing! And not without its problems. Last night I managed to get a HDMI signal to the lapdock via a rewired test board. But upon switch on for a second trail the bat54 D1 diode to pin 2 HDMI smoked and audibly popped!

So now I am thinking of testing the Atrix phone itself because... How does the phone output the 5v to HDMI pin 2 at the current required???

I think a work around will be to add a jumper cable from USB to the HDMI to remove the power draw from the Pi.

I am also planning a supper capacitor solution for lid closed temp power outs.

Any thoughts on the HDMI pin 2 power draw problem? I don't want to provide the cable to others without that safety in place, I.e. causing others the hassle of buying a new Pi or resoldering D1.

P.s. if you want D1 replacements, I will be buying a few soon [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-37353cbe-2b14-45b9-b195-070bc97196cf/contentimage_5F00_3.png:16:16]

Frustrated..

Matthew John Ritchie

@OpenECommunity for test rig pictures

RE: Raspberry Pi Lapdock HDMI cable work-around

hansaplastique — Wed, 19 Feb 2014 17:03:59 GMT

Awesome project and great info!

I've been working on my own Atrix Dock and I'm trying to replace the micro USB connector with a regular (Type A) USB connector.

However I'm stuck ....

Does anyone know the colors of the wires that comes from the HDMI+USB cable and how to connect them to a regular sized USB Type A connector?

(I'm assuming that this does not only provide power but also keyboard/mouse)

Any info would be greatly appreciated!

RE: Raspberry Pi Lapdock HDMI cable work-around

tundrwd — Fri, 13 Sep 2013 21:37:08 GMT

Update - modified my jumpered dongle with a slide switch from Radio Shack (Part # 275-006 http://www.radioshack.com/product/index.jsp?productId=3014505). It was a DPDT switch, I just cut the legs off I didn't want, only kept two so I could have a switch to turn the power on/off by making/breaking ground (see photo of modified dongle above). I shortened the jumper, soldered on the switch - made sure it worked, then slathered on some JB Weld over the circuit board. Once that had started hardening, I gently pushed the switch in the JB Weld, making sure it didn't ground out anywhere on the board. Once that had hardened, mixed up some more, and slathered it over the wires, up the switch, etc. to give some strength to the switch. Flipped the board over, slathered some more on there. The JB Weld now insulates the board, makes sure there's a firm "foothold" for the switch, and generally strengthens the overall dongle.

First pic is of the "backside" (non-switch side):

Next pic is of the switch side:

And one of the switch side that is angled to show the switch better:

I'll do a bit more JB Weld, and then clean it up a bit better. But it works fine as is.

RE: Raspberry Pi Lapdock HDMI cable work-around

tundrwd — Fri, 06 Sep 2013 23:42:47 GMT

Well, with John's help, I modified my connector/dongle, and got my Lapdock working. The Lapdock was a new-in-box English/Hebrew unit I got for $60USD (shipped). Mine was in the USA, but many are coming from Israel at this time it appears. Works just fine, but it prints on the screen backwards [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-37353cbe-2b14-45b9-b195-070bc97196cf/5277.contentimage_5F00_938.png:16:16] - just kidding!

Here's some pics, the original dongle, the "denuded" dongle (covering removed), the modified dongle (just shorted pin 17 on the TypeA connector side to ground), and the working unit in Xwindows. Mouse/keyboard work fine. I've purposely left a little extra wire, so I can add a switch later, if I want. My goal was to get the Lapdock working without modifying it at this point. May well do that later - but not now. I can encase the modified dongle in epoxy or JB Weld - something along those lines, which would even make a nice place to embed a switch. Anyway - works great. John - merci beaucoups!

[View:/resized-image/__size/200x178/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-37353cbe-2b14-45b9-b195-070bc97196cf/contentimage_5F00_190377.png:200:178]

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RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Thu, 01 Aug 2013 20:47:32 GMT

I'm hoping for a bit of advice- my lapdock recently had its HDMI port damaged on a recent trip. Is there any reason why I could not take either a mico or full size HDMI cable, cut off one end, remove the bad HDMI "port" and splice the two together? I realize it will be delicate work but I would really love to be able to use the lapdock again.

Thanks so much

Scott

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Thu, 20 Jun 2013 18:21:27 GMT

Hi John,

just wanted to let you know that your post was a big help to me when my lapdock just didn't seem to work with a RPi.

For HDMI I was using a female type D/micro to male type A adapter and a type A extension cable that just wouldn't do the job. At first I thought that the USB connection might be the problem but trying different combinations of adapters didn't improve the situation.

Now it all works perfectly! For now I put a larger switch that does not let me close the connector 'bar' properly but I will try finding a smaller one.

Thanks a lot,

Joerg

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RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Fri, 14 Jun 2013 23:16:39 GMT

Hi John.

So I scraped off the insulation on the brown wire, added a red cable and walah, works with my hdmi cable that did not support CEC. However leaving everytning plugged in and flipping the switch does nothing. I have it grounded where you did. Even when the cable that I spliced is no connect to anything it is still sending power to the pi. It's as if the switch isn't doing anything but somehow just splicing open the calbe and adding a longer cable did.... I am confused why the switch isn't working and why the pi won't turn off after I switch it. I checked the connect on the switch to make sure nothing was touching, but even when you take the grounded wire and just twist it to the wire in the pi, it powers on and stays on. What is going on!? Any ideas?

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sun, 13 Jan 2013 06:40:44 GMT

Thank you again John, ordered one straight away.

cheers Bill

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sat, 12 Jan 2013 23:20:59 GMT

Thanks John, I have been thinking about that, and came to the conclusion that I would need to connect the USB to the Lapdocks micro USB port, I still had the USB connected to a seperate power source, I did try to connect the RasPi to one of the docks normal USB ports and it loaded up the same getting to the Raspi - config.

I haven't been able to find a nice small cable to fit next to the HDMI that I also had to trim down, I will try and make the adapter slimmer so it will fit better.

If you happen to know a place where I can get one from please let me know.

Bill

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sat, 12 Jan 2013 13:39:53 GMT

Well the little light in the top left corner on the pad is on, tried Tab+Down or up no go all frozen, but the boot screen runs through fine every time and when finished it will go straight into RasPi config screen.

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sat, 12 Jan 2013 13:16:42 GMT

Hi and thanks bodgy,

Yes, actually I could see that command type "startx" but the screen goes straight into the RasPi config, don't seem to be able to stop the boot text line to type that in.

I will try your combinations and see, but so far all the keys that I tried would not work for me.

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sat, 12 Jan 2013 10:33:46 GMT

John, I have made a new SD card and it does exactly the same as the 4Gig card that I had ordered with the RasPi v.B it is. So this would eliminate a faulty SD card in my opinion at least.

I dowloaded Raspian and used Win32 DiskImager to burn to a 8Gig Category 10 SD card.

RE: Raspberry Pi Lapdock HDMI cable work-around

Former Member — Sat, 12 Jan 2013 07:59:28 GMT

Thank you John, I have made some more progress by using a different USB connection. It will now run through that boot sequence and end up at the" RasPi - config" screen with the top line high-lighted, but I am unable to move around that screen up - down, left-right,it is all frozen and it dosen't matter what keys I push on the lapdock I can't make any changes.

I was still happy to see some progress.