Uncomment:Chris1975 wrote:I have everything working except the sound. Anyone care to help? Thanks in advance
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sudo nano /boot/config.txt hdmi_drive=2
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sudo modprobe snd_bcm2835 sudo amixer cset numid=3 0
Did you get your dock from Ben's Outlet?Mr Floppy wrote:Just got delivery of the English/Hebrew version of the dock ...
There are two: I added one in the RasPi/Screens page under "HDMI", as it seemed to be the most likely place people would find it: http://elinux.org/RPi_Screens#Motorola_Atrix_LapdockMr Floppy wrote:Just got delivery of the English/Hebrew version of the dock. Only problem is that it is in the US still awaiting forwarding. Can't wait to join the ranks here.
Has anyone created a wiki on this? Can't seem to find one at eLinux.
Nice thinking, Chris. Thanks! This reminded me of something about which I've been meaning to ask.Chris1975 wrote:USB wire color codes in case someone might need it.
I did get it from Ben's outlet. There were two versions there but the Hebrew one was cheaper. Delivery to the US address was pretty quick actually. 5 days with the weekend in there. The forwarding may take a while though. Using a very cheap option. Hopefully 14 days but in the past, it has taken longer. At least it'll give me time to get the other bits of cable and connectors.FlipBumWalla wrote: Did you get your dock from Ben's Outlet?
How long do you think it will take to get it?
Sounds like you might have a lot of loss at one of the connectors. The adapter increases the voltage loss also. I was able run at 4.25V (TP1/TP2) just fine. The voltages do read a little low when back-powering.terrycarlin wrote:I have run into a problem when trying to back power the rpi from the dock. I get low voltage between tp1 and tp2. Down around 4.1v. I run into the typical problems of low voltage like repeating keys. When I power the rpi from a PSU, the voltages come up to 4.8 or so and things work fine. There is nothing on the rpi usb buss except the connection to the dock. I am wondering if my usb cable is giving me heartburn. It is a 12" male A to male A. I have an adapter to convert from the dock to the male A.
Do you have a rev 1 or rev 2 RasPi? The original rev 1 RasPi USB A ports have 140 mA polyfuses F1+F2 which have a large voltage drop at 500 mA. Normally they'd prevent back-powering from working at all, but at best they'd give you a large voltage drop. I replaced my F1+F2 with 1A single-blow fuses, with a 50 mV drop when back-powering. Later rev 1 RasPis replaced F1+F2 with 0 Ohm jumpers and rev 2 RasPis don't have F1+F2 at all, so in these cases F1+F2 are not your problem.terrycarlin wrote:I have run into a problem when trying to back power the rpi from the dock. I get low voltage between tp1 and tp2. Down around 4.1v. I run into the typical problems of low voltage like repeating keys. When I power the rpi from a PSU, the voltages come up to 4.8 or so and things work fine. There is nothing on the rpi usb buss except the connection to the dock. I am wondering if my usb cable is giving me heartburn. It is a 12" male A to male A. I have an adapter to convert from the dock to the male A.
Like itimpi, I don't use a Y connector -- I just have a short A female to Micro B female, plus an A male to A male adapter, as described in the previous comment. With the Y connector, it's very important that the Vbus only goes to the RasPi power input and that you don't swap the data lines, as that would make USB sad.o19 wrote:Hey,
I'm on my way copying this great idea, but I've some trouble with the keyboard. I've built myself a nice y-cable for powering and keyboard as described in various places around here. Power works fine and I get a screen over HDMI. However, I can not get my Pi to react on any keyboard input.
I opened the lapdock and checked the connectivity between the 30-pin connector inside and my custom usb-a end and that seems to be fine. Pin 23 goes to D+ and pin 22 to D-, both showing 0.6 ohm.
I did not dare to check voltage or current on the board or the dock, since I've never worked with electronics before. What's the things that you'd check next? Either on the software or the electronics side? I thought about asking the guys at work to use an oscilloscope to monitor the output on the data lines, when a key is pressed to make sure the lapdock is working properly (and just because I always wanted to use one of those for something non-educational), but then I've already bothered them a lot...
Any other suggestions? Maybe someone with a similar problem...
Looking forward to hearing back from you guys...
If you don't want to back-power RasPi, another approach is to use two USB cables as described in this 'blog (link). The cable+adapter from the Lapdock Micro USB plug to a RasPi A port has its Vbus wire cut somewhere to prevent back-powering. A second USB cable connects from a Lapdock USB A port to RasPi's Micro USB power jack. This is a lot clunkier than back-powering, and you have to be sure the second USB cable doesn't have a large voltage drop due to extra-thin wires. However, you do get the protection of polyfuse F3 and you don't void your RasPi warranty by modifying it.o19 wrote:Okay, thanks for the suggestions. I won't be able to check anything before Monday, but now I have at least a few things to try. Backpowering is not an option for me, since I have one of the older boards. At least not at this point in time, with some of the other options still present.
What do I need to do to power the Pi from something other than the dock? I think I still might have to do something with the Vbus of the the micro-usb on the dock or can I just leave it disconnected?
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