pleione
Posts: 11
Joined: Sat Sep 03, 2011 7:12 pm
Contact: Website

Re: Raspberry Pi Pad

Sun Sep 18, 2011 10:05 am

I've been thinking for a while about a project for an old all-in-one pc and decided that I'd like to re-purpose it as a portable Raspberry Pi Pad.

I've stripped the screen from it and intend to attach a touch screen overlay running form one of the USB ports.

I can re-wire the screen to run directly from the HDMI port.

I can build the power supply to run off batteries, I reckon a cheap 12v NiMh, available from any model shop will suffice to start with.

Powering the RasPi on it's own the batteries would be good for approx 30 hours, so once the screen and backlight are taken into account I'd be happy with anything over a couple of hours, although I suspect I can get it into the realms of any current laptop (7/8 hours).

I just need the RasPi to fill the final piece in the jigsaw.

Total project start to finish? approx 4 hours.

pleione
Posts: 11
Joined: Sat Sep 03, 2011 7:12 pm
Contact: Website

Re: Raspberry Pi Pad

Sun Sep 18, 2011 10:15 am

And no, the screen isn't LVDS, so no conversion required from HDMI.

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abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
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Re: Raspberry Pi Pad

Sun Sep 18, 2011 4:29 pm

Quote from pleione on September 18, 2011, 11:15
And no, the screen isn't LVDS, so no conversion required from HDMI.

Lucky :P
Dear forum: Play nice ;-)

jewesque
Posts: 36
Joined: Mon Oct 17, 2011 6:01 pm
Contact: Website

Re: Raspberry Pi Pad

Tue Oct 18, 2011 8:00 pm

pleione, I'd love to hear from you more on the model of this particular AiO device, and your project as it goes forward.

FYI, for saving battery power and gaining you some extra life, you could also look into converting the LCD backlight into an LED one. There are a couple pages online that I've seen where people have done that (on a smaller scale). You might be able to swing the same thing with a little reading and electrical engineering.

You can also see about what metal structures you can eliminate internally to reduce weight.

pleione
Posts: 11
Joined: Sat Sep 03, 2011 7:12 pm
Contact: Website

Re: Raspberry Pi Pad

Tue Oct 18, 2011 9:17 pm

Hi jewesque, the screen I'm using just happens to be TMDS, the same protocol that HDMI and DVI uses, once I've reconfigured the pins and soldered the new HDMI connector I'll be ready to test it, but secretly I'm waiting for my RasPi before I do too much.

I'd had the same though about LED backlighting since starting looking at the project, I've also found some interesting stuff about designing Li charging circuits, but most are SMD so need to figure out if they're possible to solder by hand.

jewesque
Posts: 36
Joined: Mon Oct 17, 2011 6:01 pm
Contact: Website

Re: Raspberry Pi Pad

Tue Oct 18, 2011 10:36 pm

Wow, that can't be fun doing SMD stuff. I've never tried, and there's a good reason for that. Good luck, and keep us posted.

- Katie

ajford
Posts: 15
Joined: Tue Sep 13, 2011 3:17 am

Re: Raspberry Pi Pad

Wed Oct 19, 2011 4:09 am

Honestly, SMD work isn't that difficult. While some SMD can be insane (0402 and smaller), most can be soldered by hand if you have a good soldering iron and some solder wick. Stick to 0805 or greater (1210 and greater is really nice when you're just starting) if you can manage, and avoid QFP when possible. But SOIC and such are pretty simple as well.

Using a radioshack firestarter to do SMD work qualifies as masochism in my book, but for about $80 you can get a great iron for SMD work: http://www.sparkfun.com/products/84

Again using radioshack solder wick is a pain but can do in a pinch. Sparkfun also carries a VERY good solder wick, which I recommend whole-heartedly: http://www.sparkfun.com/products/8775

Sparkfun has some great tutorials on it: http://www.sparkfun.com/tutori.....category/2
I've started using SMD after following their tuts, and I don't plan on going back ;) When you etch your own boards, not having to drill a ridiculous number of holes is a great relief.

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