Choosing a touch screen platform for in-home display product

I'll design a typical "in-home display" product with a small (4-6") 
touch screen display. The application will be generic, mostly oriented 
to security and/or home/building automation.

The human-machine interface is important (beautiful graphics, fast 
responses, sensible touch, ...) and the *low cost* too!!!

Does someone give me suggestions on some good platforms to start with?

Of course I have two choices.

Design the hardware (choose the microcontroller, the display, design a 
board, connectors...) and write the firmware from the scratch. Maybe I 
can use some good graphics libraries on the market (QT?) or from the 
manufaturer (Microchip Graphics Library, ...).
Anyway I have some doubts about the result.

Find and buy a ready-to-use small Android-based tablet from a China 
manufacturer. I think I can found a similar thing at 25-20$ for 1k-5k 
pieces. The price would be very good and I can decide to use the 
original cabinet or adapt a new one.

My doubts are for the OS. Android is oriented for smartphone (calls 
management) that I don't need and let the user to install apps and make 
many things. I worry the user will be able to install its applications, 
customize settings and so on.

How is Android "lockable" from the developer so the user can use *only* 
his application?

pozz <pozzugno@gmail.com> wrote:
> How is Android "lockable" from the developer so the user can use *only* 
> his application?

Do your own build.  Deselect the drivers for wifi, USB, whatever, and the
phone dialler, contacts, etc etc.  Then you have a version of Android with
no support for hardware you don't want.

If it's a China special, extracting the Android sources could be a bit
tricky (say 'GPL violation' and they just laugh).  However you could
probably pick a tablet with GPL compliance.  The other pain will be
maintaining continuity of supply because the models will change every few
months.  (And don't forget you'll have to distribute your own GPL sources).

If you want to prevent the user 'hacking' their system (which could be
finding a way to reflash new firmware, or even poking about with JTAG ports)
then you need a proper security model.  But maybe simply locking it down by
not installing stuff is enough.  (Arguably, the hackability of abandoned
hardware can save it from landfill so has a social function.  Though is a
bit of a headache as far as support goes).

Theo

On Thursday, June 5, 2014 6:40:11 PM UTC-7, Theo Markettos wrote:
> pozz <pozzugno@gmail.com> wrote:
> 
> > How is Android "lockable" from the developer so the user can use *only* 
> > his application?
 
> Do your own build.  Deselect the drivers for wifi, USB, whatever, and the
> phone dialler, contacts, etc etc.  Then you have a version of Android with
> no support for hardware you don't want.

If you can't do Wifi & Phone, what can you do with it?  OP wants in-home display of something.  I don't think it's just for simulations,

pozz <pozzugno@gmail.com> writes:
> I'll design a typical "in-home display" product with a small (4-6")
> touch screen display. The application will be generic, mostly oriented
> to security and/or home/building automation.

Look at some digital picture frames.  They have less stuff in them than
android tablets, and are cheaper.

Il giorno venerd� 6 giugno 2014 06:44:10 UTC+2, edward....@gmail.com ha scritto:
> If you can't do Wifi & Phone, what can you do with it?  OP wants in-home display of something.  I don't think it's just for simulations,

It will be connected to a proprietary wired RS485 bus, so I definitevely *don't need* WiFi and Phone.

Il giorno venerd� 6 giugno 2014 03:40:11 UTC+2, Theo Markettos ha scritto:
> Do your own build.  Deselect the drivers for wifi, USB, whatever, and the
> phone dialler, contacts, etc etc.  Then you have a version of Android with
> no support for hardware you don't want.

This seems nice, but is there a ready-to-use platform that shows this 
process? A demo that let me use and experiment with Android, starting
from build my own OS.

How simple is it?


> If it's a China special, extracting the Android sources could be a bit
> tricky (say 'GPL violation' and they just laugh).  However you could
> probably pick a tablet with GPL compliance.  

Do you know something of it?


> The other pain will be
> maintaining continuity of supply because the models will change every few
> months.  

I know, I know.


> (And don't forget you'll have to distribute your own GPL sources).
 
Should all the Android-based applications GPL released?


> If you want to prevent the user 'hacking' their system (which could be
> finding a way to reflash new firmware, or even poking about with JTAG ports)
> then you need a proper security model.  But maybe simply locking it down by
> not installing stuff is enough.  

Yes, it will be enough.

Il giorno venerd� 6 giugno 2014 06:48:25 UTC+2, Paul Rubin ha scritto:
> Look at some digital picture frames.  They have less stuff in them than
> android tablets, and are cheaper.

And what about changing the original firmware? Are there open-source 
digital picture frames?

pozzugno@gmail.com wrote:
> Il giorno venerdì 6 giugno 2014 03:40:11 UTC+2, Theo Markettos ha scritto:
> > Do your own build.  Deselect the drivers for wifi, USB, whatever, and the
> > phone dialler, contacts, etc etc.  Then you have a version of Android with
> > no support for hardware you don't want.
> 
> This seems nice, but is there a ready-to-use platform that shows this 
> process? A demo that let me use and experiment with Android, starting
> from build my own OS.

Have a look at CyanogenMod.  It builds the full OS from scratch, and works
on quite a number of devices.

> How simple is it?

Fairly straightforward - not Cyanogen, but I've built Android Open Source
Project (AOSP) for the Nexus 7.  You download a huge tarball of tools,
follow the instructions, type make, it fetches everything it needs from git
and builds the whole OS (insert lots of CPU time here).  It then starts the
image on an emulator to test it out before deploying on real hardware.

Nexus hardware is fully supported by Google which makes it less painful, but
if you get a Cyanogen-supported device it may be equivalently
straightforward.  However they're not always the bargain-basement hardware.
(There's lots of third-party ports of CM to other hardware, but that might
not be enough support for you)

> > If it's a China special, extracting the Android sources could be a bit
> > tricky (say 'GPL violation' and they just laugh).  However you could
> > probably pick a tablet with GPL compliance.  
> 
> Do you know something of it?

Not tablets, but Chinese manufacturers like Oppo are better at playing
nicely with the GPL rules.

> > (And don't forget you'll have to distribute your own GPL sources).
>  
> Should all the Android-based applications GPL released?

If you've modified the kernel sources, yes.  If you haven't you still need
to provide sources on request.  You can do that by pointing at someone
else's server, but you still need a copy of the sources in case that server
goes away.

Theo

On Friday, June 6, 2014 12:09:48 AM UTC-7, pozz...@gmail.com wrote:
> Il giorno venerd� 6 giugno 2014 06:48:25 UTC+2, Paul Rubin ha scritto:
> > Look at some digital picture frames.  They have less stuff in them than
> > android tablets, and are cheaper.
> 
> And what about changing the original firmware? Are there open-source 
> digital picture frames?

Digital picture frames are not likely to have touch or non-touch inputs.  Even for tablets (or subset like DPF), they might not be able to boot from external devices.  First thing to think about is how to load your stuffs in it, perhaps JTAG.

pozzugno@gmail.com wrote:
> Il giorno venerdì 6 giugno 2014 03:40:11 UTC+2, Theo Markettos ha scritto:
> > The other pain will be
> > maintaining continuity of supply because the models will change every few
> > months.  
> 
> I know, I know.

I should add, I think this is going to be your biggest problem.  Any work
you do could be eliminated by the manufacturer changing things overnight. 
Unless you're prepared to use the device completely stock (which is unlikely
given what probably comes on it) you may have to do customisation at short
notice.

I'd suggest this approach might be feasible if:
Your volumes are small enough that you can do a 'lifetime buy' from the
beginning, so you know all your stock is good, or
Your volumes are high enough to make a deal with the manufacturer direct

The place in the middle isn't a good spot to be.

Theo