I made a Raspberry PI Laptop


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by Lob0426 » Tue Jun 26, 2012 7:43 pm
@Jim Manley: sorry forgot the period. The Alpha boards run a pretty low wattage. They only hit like 1.2 watts running at full load. That is the difference between the linear, on the production boards, and switching regulator on the Alphas. The SoC will run on 3.3v. The USB is the item that needs 5v. @godFather89 replaced the linear with a switching regulator on his RasPi. The switching regulator will turn out a steady 3.3v with a 4.2v input.

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by magarcan » Tue Jun 26, 2012 8:49 pm
What I was thinking is emmbebed raspi inside lapdock. Maybe here:
Image

Can somebody take meassurements of lapdock width, height, etc.?
In order to make raspi smaller, an option is to remobe usb hub, ethernet connector, and jack connector...

What do you think?
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by clickykbd » Tue Jun 26, 2012 9:43 pm
Hi. I'll be joining the ranks of those attempting the PiDock soon. Dock's in the mail. Wanted to share my source for the dock since the price point seems about right and there is a bonus or two included. Purchased after watching tons of ebay "auction" style listings go higher $$, even for used, figured worth sharing.

There is a seller on ebay with multiple-stock (hundreds sold) that are refurbs for 60.00USD buy-it-now (with free US shipping). They also throw in two "short" cables, intended to make it useful for more of the Motorola phone product line, at least one of these is immediately useful to the PiDock project, perhaps both with a stubby hdmi adapter, (if you are doing a no-mod approach).

http://www.ebay.com/itm/140746182594?ss ... 521wt_1073

As they are refurbs and photo was obviously not of the exact item, I'll be sure to share further if the condition was unacceptable or it has other issues when it arrives. *crosses fingers*
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by godFather89 » Tue Jun 26, 2012 9:44 pm
Jim Manley wrote:Something is seriously wrong with these numbers.

From everything I've experienced and others have reported, there's no way a Pi can run on 4.2 volts at the supply input - none, nada, zip. Where/how was this measured?


I'm not saying that is 100% exact nor that I have a very accurate meter.
The board can run with 4.2V input, as long as you get the 3.3V needed by the SoC. Note that I removed the input fuse, USB hub and ethernet chip and replaced the linear regulator with a switching one. The battery was fully charged (also connected to the charger) and the input voltage was 4.2V (could fluctuate a little but not so much that it could influence the readings).

At idle, I got 120 mA which means 0.504 W (considering a 4.2V input voltage). Assuming that the meter is not very accurate, it could have been 0.4W or 0.6W. Anyway, it's very low.
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by godFather89 » Tue Jun 26, 2012 9:49 pm
masterofstuff124 wrote:I first had the black and yellow wire each going to power and the red and brown going to data. I would get the errors posted above. Now I have both Blacks and the yellow and the shield going to power. And the red and brown both going to usb. Same errors as above.


Note that yellow and shield is GND and the two blacks are +5V. Try connecting the USB data (+/-) and GND to a male USB and connect it to a regular PC. It should work like a regular keyboard/mouse.
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by masterofstuff124 » Tue Jun 26, 2012 11:21 pm
does not work when connected to my pc. Im not so sure it ever would. as i tried hooking my android phone via the otg adapter and never got the keyboard/mouspad to work.
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by masterofstuff124 » Wed Jun 27, 2012 12:14 am
magarcan it would not fit in that space. it would stick out/
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by godFather89 » Wed Jun 27, 2012 5:23 am
Maybe your lapdock is defective.
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by clickykbd » Wed Jun 27, 2012 7:13 am
masterofstuff124 wrote:does not work when connected to my pc. Im not so sure it ever would. as i tried hooking my android phone via the otg adapter and never got the keyboard/mouspad to work.


Was the one in question an Atrix or Droid model? Seems most people have been playing with the Atrix model ones?
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by masterofstuff124 » Wed Jun 27, 2012 2:26 pm
It is an original atrix 4g lap dock.
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by Jim Manley » Wed Jun 27, 2012 4:24 pm
Lob0426 wrote:The SoC will run on 3.3v. The USB is the item that needs 5v. @godFather89 replaced the linear with a switching regulator on his RasPi. The switching regulator will turn out a steady 3.3v with a 4.2v input.

OK, I missed what configuration was being measured, as I had read the earlier post mentioning the board component stripping and didn't correlate the two posts.

However, while the info is interesting in an intellectual way, I don't see how this is of much use to anyone not willing to tear their board down to eliminate interfaces that virtually everyone needs. You can't even operate it over a network since stripping off the Ethernet/USB controller eliminates the network as well as a USB port. If you were going to try to run it via USB WiFi or wired Ethernet, does the Model B board even have the traces to support a single USB port via the SoC if the controller is stripped off? If you're going to attach even just a USB keyboard, you're going to need the 5 volts, anyway, or are you going to rely on a battery-powered hub to pass the 5 volts back? It's feasible to measure the current draw of things like a keyboard and a mouse and subtract them from the total power draw if you're just interested in the SoC power draw. Are you envisioning running the SoC via battery with no interfaces beyond video and audio outputs?
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by lmoss30 » Wed Jun 27, 2012 5:35 pm
God father thanks for the I formation, think I will wait for my second unit before trying to many modification lol,

On a side note has anyone made the volume keys work yet?
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by Lob0426 » Wed Jun 27, 2012 6:02 pm
Jim Manley wrote:
Lob0426 wrote:The SoC will run on 3.3v. The USB is the item that needs 5v. @godFather89 replaced the linear with a switching regulator on his RasPi. The switching regulator will turn out a steady 3.3v with a 4.2v input.

OK, I missed what configuration was being measured, as I had read the earlier post mentioning the board component stripping and didn't correlate the two posts.

However, while the info is interesting in an intellectual way, I don't see how this is of much use to anyone not willing to tear their board down to eliminate interfaces that virtually everyone needs. You can't even operate it over a network since stripping off the Ethernet/USB controller eliminates the network as well as a USB port. If you were going to try to run it via USB WiFi or wired Ethernet, does the Model B board even have the traces to support a single USB port via the SoC if the controller is stripped off? If you're going to attach even just a USB keyboard, you're going to need the 5 volts, anyway, or are you going to rely on a battery-powered hub to pass the 5 volts back? It's feasible to measure the current draw of things like a keyboard and a mouse and subtract them from the total power draw if you're just interested in the SoC power draw. Are you envisioning running the SoC via battery with no interfaces beyond video and audio outputs?

The A model runs without the LAN9512. They jumper over the PCB LAN chip area so it passes directly to the single USB port. with the Lapdock having its own hub you would only need the data lines to USB, no power output. You will still need to bring power into the RasPi from the Lapdock. You end up using your one port to get two ports on the Lapdock. But you have a keyboard and pointing device already.it would make for a very minimalist install. I am sure the Lapdock would be very popular with the A model and a wireless dongle. If all you intend to use is the Lapdock you do not need the analog sound or RCA video jacks. Putting in a switching regulator would extend battery life. You could run the USB PiPass if you wanted to keep the second USB working. That is what I plan to do.

If all you wanted was access to the SoC through the Lapdock all you would need is the USB Data lines out, you would not really need 5v at all. The Lapdock would supply 5v to its hub. 3.3v runs everything else as far as I know. I think the LAN9512 needs 5v to power the Ethernet. An A model would be best to really cut down the power usage on, after some modification.
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by Jim Manley » Thu Jun 28, 2012 2:55 am
Ah, OK, so the 5 volts from the off-board micro-USB supply can be dropped to 4.2 volts to be sufficient for the SoC. That is interesting - I was wondering if the lapdock could provide the 5 volts for Pi USB. Something to consider when I can get a second Pi board that I wouldn't mind butchering ... or just wait for the A boards to become available. I probably won't have time to fool with stripping a B board down before then, anyway.

I saw that the Motorola 500 Lapdock Pro includes a 100 MB/s Ethernet port, has a webcam and VGA output for projection, has a full-sized keyboard, and features an SD card reader so, those are already addressed in next year's lapdock! No mention of a microphone for doing VOIP/conference calls, though, so, a USB mike would still be needed for that with a Pi. I suppose all of those gadgets can be sitting on an expanded USB 2.0 bus.

The screen reportedly is 1366x768, which I think is the same as on our Atrix Lapdocks, so, pixel density is lower than on the Atrix model. I also discovered that the Lapdock 100 is not the same as the Atrix version - it's made of plastic and mates only with the Razr models, as is the case for the 500, while the Atrix lapdock is primarily aluminum (that would explain 3.2 pounds for the 500 vs. 4.4 pounds for the Atrix, IIRC).

Do you think if we asked them to leave room for a Pi board inside that they would accommodate that in the next version? :D
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by Lob0426 » Fri Jun 29, 2012 3:03 am
You could run less than 5v but you have to change out the Linear Regulator for a switching first. Or put 3.3v to the RasPi after the regulator. You will not be able to power anything from the RasPi USB ports at all. The LAN9512 looks like everthing internal is 3.3v. All 5v appears to be external. So you should be able to get Data out of both ports, just not power (5v). Going over the Datasheet it looks like even the Ethernet would still work, but we need a more knowledgeable opinion on that. The downside is you will need a regulator in there somewhere to get the 3.3v. I do not remember ever seeing a 3.3v PSU. A bench PSU would do it, but who wants to carry that around with their Lapdock. :lol:

The Linear Regulator needs more overhead than 4.2 to supply 3.3v, I think. It is also one of the the worst power consumers onboard.

The A model would be a better Candidate for all of this surgery. The Pro 500 has a lot of features but it is also $349. They probably make you a pro 500 for your RasPi for that price. :evil:
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by Jim Manley » Fri Jun 29, 2012 8:11 am
It's all good to know - thanks! Regulators usually need around 1.2 ~ 1.4 volts of overhead (primarily rectifier junction drops, which is where the heat comes from), so, 4.5 volts might do it. I suspect that regulators can be obtained for any voltage if you're willing to buy a fab production run's worth ;)

Switching regulators are typically at least 90% efficient, although my experience is with the old discrete component types. I need to look at some data sheets to determine what a 3.3v surface-mount device wants, needs, and demands. As usual, exponentially-increasing price probably buys linearly-increasing performance/efficiency :x

I wonder how may Model A orders we'd have to gather in order to get the factory off the dime (or RMB, I suppose). I have lots of interest from schools for both Model As and Bs.

I'll be watching the Lapdock 500 next year, when its price will likely eventually also drop below $100 as they clear them out. I'll be watching the Amazon, etc., reviews to see if there are any show-stoppers. The most frequent complaint for the Atrix is limited performance when multiple phone apps are running. That won't affect us, of course, although we have our own lag problems until the GPU gets integrated with X and desktop-oriented apps and services.
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by neggles » Fri Jun 29, 2012 1:08 pm
You can get LDO (low-drop-out) linear regulators in small numbers from element14/premier farnell which require as little as 0.3V overhead to function, they're just more expensive (and of course the rpi is all about meeting the pricepoint for educational users) - i think i might swap out the regulator on my board for a more power efficient one and see how long it'll run with a 3F supercap on the 3.3V bus...
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by Jim Manley » Fri Jun 29, 2012 4:59 pm
neggles wrote:... see how long it'll run with a 3F supercap on the 3.3V bus...

The low-overhead regulator is a good idea.

You're probably aware, but, for those not familiar with supercaps, they can fail quite spectacularly (aka explode violently), especially when shorted or exposed to higher-than-rated voltage, but, sometimes just because of the phase of the moon. They deserve more respect than other components, so, eye protection, encasement, and other precautions are absolutely required when working with them on exposed boards. Be careful you don't short a charged one lying out on a work surface, either. Don't ask how I know more than I want to about this topic ;)
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by neggles » Fri Jun 29, 2012 5:14 pm
Jim Manley wrote:You're probably aware, but, for those not familiar with supercaps, they can fail quite spectacularly (aka explode violently), especially when shorted or exposed to higher-than-rated voltage, but, sometimes just because of the phase of the moon. They deserve more respect than other components, so, eye protection, encasement, and other precautions are absolutely required when working with them on exposed boards. Be careful you don't short a charged one lying out on a work surface, either. Don't ask how I know more than I want to about this topic ;)


I've had my fair share of supercapsplosions XD they get very upset when you don't put a resistor in series to limit charging current (or use a current limited power supply), for one... after all, exposing a capacitor to an unrestricted power source theoretically results in infinity amps for a very short period of time >.>

The most fun was when one of my friends had his automotive 15F unit commit suicide while he was driving. That was... interesting to clean up.

To be more on topic, has anyone looked further into potentially removing the folding dock section and installing the pi semi-permanently? My LapDock and associated adapter cables won't be here for another few weeks, so I can't really do anything myself :P
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by clickykbd » Sat Jun 30, 2012 12:41 am
Update about my source for a lapdock mentioned here:
viewtopic.php?p=109656#p109656

It seems I'll be RMAing the first one for exchange. Condition looked great but plugged it in to charge and it appears the battery swelled and separated the palmrest case plastics (in a non-repairable way). Don't order from these folks unless I report a happy conclusion to my exchange.

Wish me luck.
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by Jim Manley » Sat Jun 30, 2012 3:33 am
neggles - Yes, I should have said high-current situations, whether charging or discharging. At least there's usually a much more limited supply of coulombs during discharge than during unrestricted charging - that is definitely a worst case that I'm not sure even Murphy would have thought of ... Oh, who am I kidding? That's precisely his modus operandi - acting when the one trivial corner case you didn't think through occurs! :cry:

Bummer about the swollen battery clickykbd, especially since multiple suppliers on Amazon are selling them in single quantity for about $65 new and unopened, including free shipping from Amazon fulfillment. Plus, there's no stated inventory levels, which suggests maybe dozens are available from each supplier, at least. I'm extremely happy with mine, so far. Hope all's well that ends well.
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by Lob0426 » Sat Jun 30, 2012 4:29 pm
I bought one the refurb ones with cables and it charged just fine. Have not received the adapters to try anything else out yet.
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by clickykbd » Sat Jun 30, 2012 6:59 pm
I didn't gut it to see if battery swell was really the cause (because I intend to return it), could have just been damaged in shipping and didn't reveal so until I started handling it. It did act like it was charging anyway. But glad to know some folks got a good unit from them.

Price was equivalent to those amazon stores and those stubby cables looked really handy.

PS - please leave some stock so they have something to exchange with me! No weekend business hours. :-(
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by Syliss » Sat Jun 30, 2012 10:48 pm
Ordered my HDMI converter from ebay last week, hope it gets here soon. My lapdock came fast from Amazon for $65 (2 day with free prime trial!).

Was thinking of using this usb cable for power/data. Just cut off one end for data! Anyone tried this cable before?
http://www.dealextreme.com/p/micro-usb- ... 0cm-107901
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by Jim Manley » Sun Jul 01, 2012 1:33 am
Syliss wrote:Was thinking of using this usb cable for power/data. Just cut off one end for data! Anyone tried this cable before?

Nice! I might just order one once I know it works. The only potential glitch could be if the cable conductors are on the skimpy side, since we now know that the Pi can draw upwards of 1,000 ma of current, even more depending on what's plugged into the USB ports. Higher current results in a larger voltage drop across the cable, and the Pi is touchy enough about low voltage as it is. At least the cables aren't very long, as that also contributes to voltage drop.

When you say cut off one end for data, what are you going to connect the cut end to, a full-sized type A male USB plug? Any idea what the icon with the X through it on the female end of the cord means?
Femaile_MicroUSB_to_Dual_Male_MicroUSB_Cable_50.png
Femaile_MicroUSB_to_Dual_Male_MicroUSB_Cable_50.png (59.26 KiB) Viewed 5198 times
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