cheap tablet as control interface?

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cheap tablet as control interface?

Postby jbeale » Tue Nov 06, 2012 3:07 pm

I'm thinking about a display and control interface for a home sensor network (shows current room temperatures, lights, occupancy, etc.).

I see that you can get Android 4 tablets with a 7" 800x480 capacitive touchscreen for under $60 now, for example this one: http://www.gadgetsdealer.com/product126439.html

At that price it's nearly the same cost as the display alone, and it includes battery, wifi, 4GB memory and a 1 GHz processor. Is there any reason I couldn't use this as my control interface, to display and interact with a simple locally-served webpage from a Raspberry Pi showing sensor status, etc.? I doubt I'm the first person to have this idea- is anyone using this type of tablet as a dedicated control surface? How well does it work in this application?
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Re: cheap tablet as control interface?

Postby Sjaak » Tue Nov 06, 2012 5:49 pm

The only downside could be the power connector which will protude.
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Re: cheap tablet as control interface?

Postby dps » Tue Nov 06, 2012 7:37 pm

Has anyone here successfully ordered from GadgetsDealer? I searched for them on Google and got very mixed reviews...
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Re: cheap tablet as control interface?

Postby jbeale » Tue Nov 06, 2012 8:44 pm

Based on this answer, it looks like "buyer very much beware" from that site. Something like ebay, but even more so.
http://answers.yahoo.com/question/index ... 336AA4xQp8
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Re: cheap tablet as control interface?

Postby dps » Tue Nov 06, 2012 9:18 pm

Yeah, I think I'll steer clear. While I'd certainly be up for buying a $60 Android tablet if it's hackable (and if it works at all), it's not worth the risk in this case. :-)
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Re: cheap tablet as control interface?

Postby jbeale » Tue Nov 06, 2012 10:53 pm

Well, almost the same thing goes for $63 on ebay. Supposedly that vendor has sold 40 of them, and has ok recent feedback on these items. I suppose they might all be fake. Hopefully I'll see a real review of this item somewhere.

http://www.ebay.com/itm/7-Google-Androi ... 1e72bcb99a
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Re: cheap tablet as control interface?

Postby matseng » Wed Nov 07, 2012 2:12 am

The price is not unreasonable. Two weeks ago I was at Low Yat Plaza in Kuala Lumpur (it's a 6 storey building completely jam packed with small it/computer/phone stores) for having the LCD replaced in my wifes laptop. And a few of the outlets there sold 7" Android pads for 199 ringgits = $65. I almost bough one on my out of there but I restrained myself in time... :-)
Last edited by matseng on Wed Nov 07, 2012 9:02 am, edited 1 time in total.
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Re: cheap tablet as control interface?

Postby dps » Wed Nov 07, 2012 7:59 am

Hmm. Tempting!

I wonder how difficult it would be to put Linux (Android-less Linux) on such a tablet... I suppose that's a question for another time (and thread). :p
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Re: cheap tablet as control interface?

Postby arupbsk » Wed Nov 14, 2012 10:14 am

WOW. I didn't know tablet market has these cheap prices now. 2 year ago, I bought one for $180. I just saw a 4.3" small tablet running 1.2Ghz CPU, etc at $45 in DX.

@jbeale
You can probably use the IOIO boad to have many GPIO from a android device or tablet. And you design the UI for your device too. http://www.sparkfun.com/tutorials/280
Still learning
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Re: cheap tablet as control interface?

Postby bearmos » Wed Nov 14, 2012 10:42 am

jbeale wrote:Hopefully I'll see a real review of this item somewhere.


That would definitely make me rest a little easier before buying one. I noticed one of the variants on ebay a while back - it's definitely tempting to pick one up. It was hard to believe something viable existed in the $60 range after starting the search with $400+ tablets in mind.

I imagine these ultra-cheap tablets are going to be a little less responsive and have less battery life than their more expensive counterparts - the real question to answer is "how much less" :)
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Re: cheap tablet as control interface?

Postby jbeale » Wed Nov 14, 2012 1:03 pm

Yes, the details are key... if it's slow, or has short battery life, that's probably OK for my purposes. But if the wifi is unreliable, or it locks up for any reason, then it's not useful.
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Re: cheap tablet as control interface?

Postby TonyD » Thu Nov 15, 2012 5:52 am

Back in the day, before tablets, when mobile computing meant you had a PDA. We used Palm Pilots and Handspring Visor's as user interfaces. The early Pilot's and Visor's had a serial port so it made interfacing them to your gear a breeze. And even before the world know what PDA stood for, we used the Psion Organiser for the same purpose.

Returning to the present, FDTI have a USB chip designed for interfacing to Android tablets so it could make interfacing to cheap Android tablets easier.
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Re: cheap tablet as control interface?

Postby bearmos » Thu Nov 15, 2012 7:55 am

TonyD wrote:FDTI have a USB chip designed for interfacing to Android tablets so it could make interfacing to cheap Android tablets easier.


I was wondering what would be special about a chip that FTDI would be making something application specific, like the FT311D you mentioned. Based on this white paper It sounds like the FT311D is actually a USB host, which doesn't require special drivers on the android side. Seems like a great idea for peripheral aimed at consumers.

It sounds like the main advantage of the FTDI chip is that it doesn't require rooting of the android device - I wonder how useful something like that would be for most developers. I imagine most DIY projects would probably prefer a virtual serial port instead of dealing with the Open Accessory Mode. It seems like the (like the IOIO (which looks to be pretty much just a PIC24), or any other USB based micro or FTDI bridge would be useful for this.
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Re: cheap tablet as control interface?

Postby Sjaak » Thu Nov 15, 2012 8:22 am

regarding the ft311: http://dangerousprototypes.com/2012/11/ ... and-above/

Not a big problem yet, but something to take into account. I hope they will come up with a solution for newer androids.
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Re: cheap tablet as control interface?

Postby bearmos » Thu Nov 15, 2012 8:36 am

Sjaak wrote:regarding the ft311: http://dangerousprototypes.com/2012/11/ ... and-above/

Not a big problem yet, but something to take into account. I hope they will come up with a solution for newer androids.


Maybe by the time the chips are actually available FTDI will have rev'ed the silicon. Based on a comment on the blog it sounds like this may have already happened.
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