Questions about cheap tablets as embedded components.

May 22, 2013
2
0
Hello!

I have a few questions regarding using cheap android tablets as non-tablets in devices.

First off, some background: I design and build miniature arcade cabinets. Up until this point, I've used 3.5" LCDs with composite video input, along with the guts of cheap "TV Games" -- the battery powered doo-dads they sold at big box stores for a while, that have composite A/V output for playing Atari classics and whatnot. Up to this point, that's been the quick and easy way to get things done.

HOWEVER, now, I've been told that I should start producing more of these things, and with the complications of scavenging "TV Games" on the secondhand market, as well as the limitations in using them, I've decided that I need to rethink my electronics, and use something that supported MAME. My first thought was using my existing 3.5" screens with a Raspberry Pi, since it's one of the few dev boards that supports composite video out. However, after spending a while learning just how difficult they were to obtain in quantity, I moved on and looked at some of the A10 development boards, which seem to be easier to obtain in supply, and also have composite video output.

I then started noticing a whole slew of the 5"/7" chinese tablets for less than the cost of a bare dev board + 3.5" LCD. I've been looking around for a little while, but the number on the market is just staggering, and I'm fairly new to the idea of using Android as an embedded sort of system that could function as a dedicated MAME machine, and can't find a whole lot of reference to this sort of thing being done. I was originally planning to use a stripped down linux distribution on a dev board, and boot directly into MAME on power up. I'm not sure how Android can handle this, and I'm really confused about the number of different tablet architectures out there. I find a lot of the specs to be kind of sketchy or hazy about whether the devices support USB OTG (for arcade controls) and other such things.

One of my biggest concerns is starting to use a device, and then discovering that it has been discontinued shortly thereafter, and then having to start all over again to get the new device shipshape and bristol fashion. I've been looking at the Android TV Stick devices as well, since that was essentially where I was at with both my TV games and dev boards, but they don't like to support composite video output, and finding cheap LCDs that take HDMI seems a bit difficult, and will push the cost further than I'd like to go.

I apologize if this seems a bit rambling, I've got a lot of food for thought here, and I'm hoping some of all y'all can help me sort it out!

Cheers!

-C
 

J515OP

Super Moderator
Staff member
Jan 6, 2011
5,172
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Welcome to the forum. You bring up lots of interesting points. You sound like you know what you are doing and already have a handle on this issues.

1) Android can pretty much do anything you want.
2) Hardware is going to be the issue. You are going to want a hardware that is widely supported and well hacked. When you find hardware with the specs you need see if there is an active development community for it.
3) It seems like most of the devices these days support USB OTG. You should be able to quickly determine this from the active developer community supporting the device you choose.
4) There is a very real risk of non-branded Chinese (and even major brand) hardware being discontinued and phased out. There is always something new on the horizon so you want a device that has a huge resale market or you may have to go directly to the Chinese supplier and see if you can order in bulk.
5) Micro HDMI is pretty broadly available.

Here are some links to the forums that might be good places to start.

Huawei Tablets
Coby Tablets
Viewsonic Tablets
Foreign Tablets
More Android Tablets
 
May 22, 2013
2
0
Welcome to the forum. You bring up lots of interesting points. You sound like you know what you are doing and already have a handle on this issues.

Thank you for the welcome :) I really appreciate it!

1) Android can pretty much do anything you want.

I've kind of come to this conclusion -- my biggest hurdle is trying to figure out how to make it do what I want. The hardware/software compatibility thing isn't nearly as simple as it is on more "traditional" x86 or ARM Linux fronts, and the fragmentation is a bit daunting. I'm not exactly the best software guy in the world, and am trying to find a good place to start learning and making sense of things.

2) Hardware is going to be the issue. You are going to want a hardware that is widely supported and well hacked. When you find hardware with the specs you need see if there is an active development community for it.

yeah, I'm figuring this. Given the sheer volume of options for brand and whatnot that are out there, it's tracking things down that is going to be the fun part. I've noticed that a LOT of the cheap tablets seem to be branded differently, but with identical specs. I figure there are only a few different tablet manufacturers out in China who are turning out the dozens of brands, so I'm presuming a lot of the hardware is pretty much identical under the hood. That's a dangerous assumption, but I'm wondering if some of the experienced folks could help shed some light on something. When it comes to alternate firmwares and customizations and whatnot, is there any sort of crossover for replacement firmware that can be used on units with the same chipset (i.e. Allwinner A10/Mali 400, etc.)

3) It seems like most of the devices these days support USB OTG. You should be able to quickly determine this from the active developer community supporting the device you choose.

Thank you! This sort of corroborates my hunch. A lot of them don't really list their specs, but I've been thinking it's worthwhile to give it a try and see what happens, given they're as cheap as they are. Find a likely suspect and give it a shot.

4) There is a very real risk of non-branded Chinese (and even major brand) hardware being discontinued and phased out. There is always something new on the horizon so you want a device that has a huge resale market or you may have to go directly to the Chinese supplier and see if you can order in bulk.

I was afraid of that. If that's the case though, my main concern is how difficult it would be to port my customizations of the OS/applications over to a new platform that evolves. As I said, I'm not really a software guy (and right now working on proof of concept. I plan to source someone who knows what they're doing and pay them once I've proven that the idea is workable) and am just trying to get an understanding of what I'm getting myself in to.

A tablet isn't my first and ideal choice, since it's rather more complex and has more "stuff" in it than I need. In reality, the battery, cameras, touchscreen, wireless, and etc are pretty superfluous for my idea. I'm just looking at the tablets because it seems there are several out there with enough "oomph" to run what I need to, for a lot cheaper than buying a Raspberry Pi/Hackberry/Cubieboard and a screen to go with it. I'm having to compromise and redesign around a tablet, since my original design uses a 3.5" screen, with a 4:3 aspect ratio, but costs run up in a big hurry when I consider all of the support equipment I need to go along with it. It's kind of insane to think that a full on tablet is cheaper than going with a bare board and a bare LCD with no digitizer on it.

I'd looked at the TV sticks as well, but then, HDMI output only (no composite) and small screens with HDMI input are ridiculously expensive. I think I pay about $20 for my composite video screens in onesies right now, but I could probably get a better deal if I bought in quantity.

5) Micro HDMI is pretty broadly available.
Yeah, found that. It;s not the output though that I'm concerned about, it's finding small, affordable screens that take it as an input, most of which are more expensive than a full on 7" chinese tablet. Kinda crazy really when you think about it.

Here are some links to the forums that might be good places to start.

Huawei Tablets
Coby Tablets
Viewsonic Tablets
Foreign Tablets
More Android Tablets

Thanks! I'll be sure to check them out!

Again, thank you very much for your reply, I really do appreciate you taking the time to answer my rambling questions!

-C
 
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