Very low-cost Android-based touch panel for HMI

[pozz]

I need a very low-cost (50USD for quantity) touch panel running Android
OS. I'll use only the LCD, the touch panel and a serial interface
(RS485). A USB device port (to make a connection with a PC) and/or USB
host port (for connecting USB pen drives) would be nice. The size of
LCD could be from 5 to 7".

I don't need SD, Ethernet, WiFi, CAN, RTC, battery, Bluetooth and other
nice things. Just a serial interface. And I don't need many features
of Android, such as addressbook, phone calls and messages management,
TCP/IP and Internet connections, app installation flexibility and
similar things.

The final application will be a HMI with good graphics and human
interactions (like on Android smartphones).

I know I can use a powerful CPU core module (generally with a SODIMM
interface) and design a custom mainboard, but I think the final price of
the widget will be higher than my target low price.

I'm ready to design my custom board with MPU and memories, but I need to
start at least from a reference design with schematics and software
(Android) running well. I don't have the knowledge to hack the
Android/Linux kernel.

Any suggestions on a off-the-shelf product or a open hardware design to
start from?

[Les Cargill]

You pretty much get Ethernet, Wifi, SD, RTC and battery with most of
the high-volume Android offerings. The problem will be term of
availability. For 7", there are a dizzying array of sub-$150 offerings.
There's no cost savings by making your requirements more modest.

They do not, however, have RS485 natively.

Just IMO, but if I needed 485, I'd buy a Cubie or RasPi, plug a $5.00
485 adapter into one of the USB slots and connect to it via WiFi.

Android app development is pretty much a "walled garden".

--
Les Cargill

[Paul Rubin]

pozz <pozz...@gmail.com> writes:
> I need a very low-cost (50USD for quantity) touch panel running

What quantity do you have in mind? Does it absolutely have to run
Android? An old client of mine built something like that for their own
application (retail kiosk) and it is quite nice, but runs a more generic
Linux. Maybe they could work something out with you if you want enough
of them. Their thing has a 3.5" touchscreen and uses a USB client port
for power and network. It has an internal serial port so maybe that
could be brought out as RS-485 with a little bit of customization.

> Any suggestions on a off-the-shelf product or a open hardware design
> to start from?

For really big quantity you might try archos.com which can customize
their hardware for you:
http://www.archos.com/us/corporate/company/bizdev.html

[rickman]

Do you think your price target is realistic? For $50 you will be hard
pressed to find a small tablet which is about your specs minus the
RS-485 plus a few very low cost peripherals. I would think they way to
go is to find the lowest priced tablet you can and add a USB RS-485
adapter.

http://www.dxsoul.com/product/gonomad-p702a-7-action-7013-android-4-1-tablet-pc-w-512mb-ram-4gb-rom-black-901295052#.VAt6ixY9TAk

Even the Beagle Bone Black is $45 to start and that doesn't include the
LCD or touchscreen.

--

Rick

[edward....@gmail.com]

> > I need a very low-cost (50USD for quantity) touch panel running Android OS. I'll use only the LCD, the touch panel and a serial interface (RS485). A USB device port (to make a connection with a PC) and/or USB host port (for connecting USB pen drives) would be nice. The size of LCD could be from 5 to 7".

> > I don't need SD, Ethernet, WiFi, CAN, RTC, battery, Bluetooth and other

Sound like you don't really need Android. You are spec'ing out everything that need Android/Linux/networking.

> > The final application will be a HMI with good graphics and human interactions (like on Android smartphones).

Or just a good micro with touch screen LCD.

> Do you think your price target is realistic? For $50 you will be hard pressed to find a small tablet which is about your specs minus the RS-485 plus a few very low cost peripherals. I would think they way to go is to find the lowest priced tablet you can and add a USB RS-485 adapter.

Might be doable if qty is high enough. I am thinking perhaps in 10K pcs.

[hamilton]

I have been looking for a low cost tablet with Bluetooth.

I have found a few, seems like BT is to costly for most manufactures to add.

There are some BT terminal programs out in the wild, but they do not
always work with the tablets I have got.

I got a 7" Lenovo Ideatab A2107A-F (Ver 4.0.3) on sale and BlueTerm does
work with it.


Now to get my own App to work with that.

hamilton

[pozz]

Il 06/09/2014 22:30, Les Cargill ha scritto:
> Just IMO, but if I needed 485, I'd buy a Cubie or RasPi, plug a $5.00
> 485 adapter into one of the USB slots and connect to it via WiFi.

I need to connect the touch panel to a RS485 bus, so I'd plug a USB/485
adapter to RasPi. I don't need WiFi at all.

>
> Android app development is pretty much a "walled garden".
>

I don't know, because I've no knowledge about development on Adroid.
But I use Android-based smartphones and the human interactions through
touch movements and graphics are very nice.

With a full features framework like Android, the final app will be very
simple: sending/receiving messages to/from RS485 bus, put some data on
display and get commands from the user through touch screen.
I don't need to access any difficult hw devices.

I could use just Linux and abandon the idea to use Android, but the
question will be: is it possible to create the same or a similar
look&feel with bare Linux? ...without spending too much time to reinvent
and rewrite the same things already written in Android OS?

[pozz]

Il 07/09/2014 00:38, edward....@gmail.com ha scritto:
>>> I need a very low-cost (50USD for quantity) touch panel running Android OS. I'll use only the LCD, the touch panel and a serial interface (RS485). A USB device port (to make a connection with a PC) and/or USB host port (for connecting USB pen drives) would be nice. The size of LCD could be from 5 to 7".
>
>>> I don't need SD, Ethernet, WiFi, CAN, RTC, battery, Bluetooth and other
>
> Sound like you don't really need Android. You are spec'ing out everything that need Android/Linux/networking.

But I need a LCD with a touch screen.

>>> The final application will be a HMI with good graphics and human interactions (like on Android smartphones).
>
> Or just a good micro with touch screen LCD.

This is interesting. Do you think I could reach the same or similar
look&feel of Android without Android? Could you suggest an OS and
graphics frameworks or libraries to use? Mostly for touch management?

>> Do you think your price target is realistic? For $50 you will be hard pressed to find a small tablet which is about your specs minus the RS-485 plus a few very low cost peripherals. I would think they way to go is to find the lowest priced tablet you can and add a USB RS-485 adapter.
>
> Might be doable if qty is high enough. I am thinking perhaps in 10K pcs.
>

Yes, the quantity will be about 5k/10k.

[edward....@gmail.com]

On Saturday, September 6, 2014 11:17:56 PM UTC-7, pozz wrote:
> Il 07/09/2014 00:38, edward....@gmail.com ha scritto:
>
> >>> I need a very low-cost (50USD for quantity) touch panel running Android OS. I'll use only the LCD, the touch panel and a serial interface (RS485). A USB device port (to make a connection with a PC) and/or USB host port (for connecting USB pen drives) would be nice. The size of LCD could be from 5 to 7".
>
> >>> I don't need SD, Ethernet, WiFi, CAN, RTC, battery, Bluetooth and other
>
> > Sound like you don't really need Android. You are spec'ing out everything that need Android/Linux/networking.
>
> But I need a LCD with a touch screen.

A high end micro can drive LCD and touch screen.

> >>> The final application will be a HMI with good graphics and human interactions (like on Android smartphones).
>
> > Or just a good micro with touch screen LCD.
>
> This is interesting. Do you think I could reach the same or similar look&feel of Android without Android? Could you suggest an OS and graphics frameworks or libraries to use? Mostly for touch management?

You can still port part of Android/Java to your device. Think of it as a picture frame with custom touch screen. If you don't need Wifi/Networking and flexible apps loading, you can reduce the RAM footprint and FLASH much of your app.

> >> Do you think your price target is realistic? For $50 you will be hard pressed to find a small tablet which is about your specs minus the RS-485 plus a few very low cost peripherals. I would think they way to go is to find the lowest priced tablet you can and add a USB RS-485 adapter.
>
> > Might be doable if qty is high enough. I am thinking perhaps in 10K pcs.
>
> Yes, the quantity will be about 5k/10k.

There are picture frames for around $20 to $30. Upgrading the micro and touch screen can be done for less than $20. If you device is always USB power/connected, you might not even need the battery.

[Les Cargill]

pozz wrote:
> Il 06/09/2014 22:30, Les Cargill ha scritto:
>> Just IMO, but if I needed 485, I'd buy a Cubie or RasPi, plug a $5.00
>> 485 adapter into one of the USB slots and connect to it via WiFi.
>
> I need to connect the touch panel to a RS485 bus, so I'd plug a USB/485
> adapter to RasPi. I don't need WiFi at all.
>

But chances are you'd possibly have WiFi between the RasPi and the
Android already.


Ideally, you *should* be able to build things such that either could
work. I say that without that much knowledge of what building an Android
app looks like.

>>
>> Android app development is pretty much a "walled garden".
>>
>
> I don't know, because I've no knowledge about development on Adroid. But
> I use Android-based smartphones and the human interactions through touch
> movements and graphics are very nice.
>

Understood.

> With a full features framework like Android, the final app will be very
> simple: sending/receiving messages to/from RS485 bus, put some data on
> display and get commands from the user through touch screen.
> I don't need to access any difficult hw devices.
>

One point I'm trying to get across :) - RS485 is a largely alien
technology in the RasPi/Android sphere. Paradoxically, WiFi isn't.

WiFi is also... wireless.

Pretty sure these work with just about all the RasPi class devices
http://www.newegg.com/Product/Product.aspx?Item=9SIA2C513H3102

I know they work with a Cubie running Lubuntu.

> I could use just Linux and abandon the idea to use Android, but the
> question will be: is it possible to create the same or a similar
> look&feel with bare Linux? ...without spending too much time to reinvent
> and rewrite the same things already written in Android OS?
>

Either could work. I have no way of estimating cost of development
for you doing the work. SFAIK, you will have to conform to the
expectations of the Android SDK.

https://developer.android.com/training/basics/firstapp/index.html?hl=p

I don't think Ken Thompson done it that-away.

--
Les Cargill

[edward....@gmail.com]

> One point I'm trying to get across :) - RS485 is a largely alien technology in the RasPi/Android sphere. Paradoxically, WiFi isn't.

In Android, you deal with socket at the low level and url at the high level, just like most standard software under UNIX/Linux. And in the old days, UNIX runs with serial connections, without Wifi.

As long as you have ppp, slip or something on RS485. Android/Java would not know or care about what's running under it.

[Les Cargill]

edward....@gmail.com wrote:
>
>> One point I'm trying to get across :) - RS485 is a largely alien
>> technology in the RasPi/Android sphere. Paradoxically, WiFi isn't.
>
> In Android, you deal with socket at the low level and url at the high
> level, just like most standard software under UNIX/Linux.

But while they are similar, serial port connections aren't exactly
the same API as for sockets. You talk about ppp/slip - to be sure.
That's doable... but...

There's this:
http://examples.javacodegeeks.com/android/core/socket-core/android-socket-example/

Not exactly daunting, but still a parcel of work.

> And in the
> old days, UNIX runs with serial connections, without Wifi.
>
> As long as you have ppp, slip or something on RS485. Android/Java
> would not know or care about what's running under it.
>

I've little doubt that's true, but I don't think you have to add
anything to get WiFi on an Android, but you have to add an RS485
adapter and it'll be (possibly) quite a bit slower. If you can get
things to agree to a 1/4 Mbit connection, then it's probably fast
enough - although most likely it's still half-duplex ( and will have
long turnaround times ).

If I make my guess, the Wifi dongle for a RasPi will be about the same
cost as two RS485 adapters.

--
Les Cargill

[Theo Markettos]

rickman <gnu...@gmail.com> wrote:
> Do you think your price target is realistic? For $50 you will be hard
> pressed to find a small tablet which is about your specs minus the
> RS-485 plus a few very low cost peripherals. I would think they way to
> go is to find the lowest priced tablet you can and add a USB RS-485
> adapter.
>
> http://www.dxsoul.com/product/gonomad-p702a-7-action-7013-android-4-1-tablet-pc-w-512mb-ram-4gb-rom-black-901295052#.VAt6ixY9TAk

I'd be tempted to look at the various Allwinner-based tablets coming out of
China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as
far as software openness goes - that means there's a little more of an
ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner
SoC, and maybe a wifi chip and battery. Beware of the batteries, they may
not be high quality - you could disconnect them if not needed. I'm assuming
you'd want it rooted, so check there is root available.

In theory, if the innards are the same as other Allwinner tablets you're
insured a bit from supply-chain issues: the SoC is the same so pick up
another cookie-cutter tablet. Contacting the factory on Alibaba might be
the way to get a more consistent supply (but be prepared for language
issues).

But a warning: you're at the 'cheap junk' end of the market here. It may
work, but what you save on ticket price you might spend instead on supply
hassles. But could be worth it if the volume is high and the timescale is
short (don't expect the same to be available next year).

Theo

[hamilton]

Just ran across this:

http://www.alibaba.com/product-detail/VESA-Mounting-Android-Tablet-Integrated-low_900890641.html

It does state that it has RS485.

hamilton

[edward....@gmail.com]

> I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.

It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.

[rickman]

I did a search on Alibaba and found a number of units. Not sure of all
the prices but $50 sounds like it could be in the range. Only one
clearly supported RS-485 and showed a module in the image, but said it
was an option. Some of the others said RS-485 in the list of
features/interfaces, but weren't clear about it while others only
mention RS-485 in the listing title. Still, it might be worth setting
up a conversation with a few of them. Certainly this is the easy route
to hardware if you can be sure they will be making them long enough to
suit your needs. I guess you can always find a newer, similar unit if
they stop making this one.

--

Rick

[Les Cargill]

Theo Markettos wrote:
> rickman <gnu...@gmail.com> wrote:
>> Do you think your price target is realistic? For $50 you will be hard
>> pressed to find a small tablet which is about your specs minus the
>> RS-485 plus a few very low cost peripherals. I would think they way to
>> go is to find the lowest priced tablet you can and add a USB RS-485
>> adapter.
>>
>> http://www.dxsoul.com/product/gonomad-p702a-7-action-7013-android-4-1-tablet-pc-w-512mb-ram-4gb-rom-black-901295052#.VAt6ixY9TAk
>
> I'd be tempted to look at the various Allwinner-based tablets coming out of
> China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as
> far as software openness goes - that means there's a little more of an
> ecosystem about it.

There is still usually a "blob" in the BSP parts for 'em.

> Such a tablet is basically a touchscreen, the AllWinner
> SoC, and maybe a wifi chip and battery. Beware of the batteries, they may
> not be high quality - you could disconnect them if not needed. I'm assuming
> you'd want it rooted, so check there is root available.
>
> In theory, if the innards are the same as other Allwinner tablets you're
> insured a bit from supply-chain issues: the SoC is the same so pick up
> another cookie-cutter tablet. Contacting the factory on Alibaba might be
> the way to get a more consistent supply (but be prepared for language
> issues).
>

The thing that might be important is to find the OTG port and image-off
the NAND.


I know the Cubie boards have quite a bit of community for them; it's not
clear that this is true of the tablets. And it's anything but clear how
much they'd all have in common

> But a warning: you're at the 'cheap junk' end of the market here. It may
> work, but what you save on ticket price you might spend instead on supply
> hassles. But could be worth it if the volume is high and the timescale is
> short (don't expect the same to be available next year).
>

You really kind of have to be your own escrow service. You can always
eBay off extras.

> Theo
>

--
Les Cargill

[Dave Nadler]

On Saturday, September 6, 2014 10:55:40 AM UTC-4, pozz wrote:
> I need a very low-cost... with serial interface (RS485).

To clarify, you need a RS485 driver that supports operation
on a multi-drop link, with addressed and broadcast reception,
and/or master function? (as opposed to simple point-to-point)

[lang...@fonz.dk]

Den søndag den 7. september 2014 20.33.31 UTC+2 skrev edward....@gmail.com:
> > I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.
>
>
>
> It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.

I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ram, 4GB flash for 50$

if you buy parts and build something with a 7" lcd and capacitive touch
yourself I'd think $50 is hard to meet, even with a single chip micro

-Lasse

[edward....@gmail.com]

On Sunday, September 7, 2014 3:45:58 PM UTC-7, lang...@fonz.dk wrote:
> Den søndag den 7. september 2014 20.33.31 UTC+2 skrev edward....@gmail.com:
>
> > > I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.
>
> > It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.
>
> I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ram, 4GB flash for 50$

Yes, economy of scale.

> if you buy parts and build something with a 7" lcd and capacitive touch yourself I'd think $50 is hard to meet, even with a single chip micro

Doable for 10k pcs. You can get parts much cheaper than retail.

[hamilton]

On 9/7/2014 4:45 PM, lang...@fonz.dk wrote:

@Lasse

Please post which store you have found this tablet.

By store you mean something local to you home country, with out shipping ?

Correct ?

[pozzugno]

Yes, but those kind of functionalities can be implemented in software
(directly in the app). I need only the reception and sending of bytes:
it will be the app that accumulates bytes in a reception FIFO, detects a
complete message, parses it and answers to it.

[upsid...@downunder.com]

On Mon, 08 Sep 2014 08:53:25 +0200, pozzugno <pozz...@gmail.com>
wrote:

With any two wire half duplex RS485 connections, the data direction
control timing is very critical and should be implemented in hardware.
Trying to implement in software, especially high data rates can fail
quite badly.

Turning off the transmitter e.g. when the last byte of the message has
been loaded into the shift register but not yet shifted out and the
receiver will receive the last (MSB bits as ""1"). For instance the
14550 style UARTs can generate an interrupt when the last byte is
loaded into the shift register, but _not_ when the byte has been
completely shifted out, so you have to poll the Tx busy bit in a tight
loop or read back the transmitted byte on the Rx pin.

Keeping your transmitter long after the last bit has actually been
transmitted out and the other partner may already have started to send
the response and there is a collision.

[pozzugno]

Il 08/09/2014 09:15, upsid...@downunder.com ha scritto:
> On Mon, 08 Sep 2014 08:53:25 +0200, pozzugno <pozz...@gmail.com>
> wrote:

>> Yes, but those kind of functionalities can be implemented in software
>> (directly in the app). I need only the reception and sending of bytes:
>> it will be the app that accumulates bytes in a reception FIFO, detects a
>> complete message, parses it and answers to it.
>
> With any two wire half duplex RS485 connections, the data direction
> control timing is very critical and should be implemented in hardware.
> Trying to implement in software, especially high data rates can fail
> quite badly.

Yes, you're right. So I need an Android OS with a RS485 driver... I
don't know if it's difficult.

[Ian Malcolm]

pozz <pozz...@gmail.com> wrote in news:luf79c$5l8$1...@dont-email.me:

If you can stand a mono eInk display, look at ebook readers. A very
popular one for repurposing is the Kobo Touch. It has multiple logic
level serial ports accessible on its board, runs Linux and writing GUI
apps for a jailbroken Kobo is a well-trodden path.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL

[lang...@fonz.dk]

yes it is a local and postorder hardware store,
http://www.harald-nyborg.dk/p3435/denver-tablet-tad-70111

but if they can sell it for ~52$ including our 25% VAT, I can't imagine buying
a case of them from china cost much

just look at dealextreme

http://www.dx.com/c/laptops-tablets-1499/tablets-1409?sort=price&sortType=asc

-Lasse

[lang...@fonz.dk]

yes, but for anything "android fancy" 2M flash and 512K sram isn't nearly
enough, even in a lowly 256 colors the frame buffer alone will take up 80%
of the ram

-Lasse

[edward....@gmail.com]

> > > > > I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.
>
> > > > It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.
>
> > > I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ram, 4GB flash for 50$
>
> > Yes, economy of scale.
>
> > > if you buy parts and build something with a 7" lcd and capacitive touch yourself I'd think $50 is hard to meet, even with a single chip micro
>
> > Doable for 10k pcs. You can get parts much cheaper than retail.
>
> yes, but for anything "android fancy" 2M flash and 512K sram isn't nearly enough, even in a lowly 256 colors the frame buffer alone will take up 80% of the ram

You can get custom LCD controller with

[edward....@gmail.com]

(my laptop keeps acting on it's own mind.)

You can get custom LCD controller with frame buffers. You can even implement drawing primitives in the LCD controller, or even a Java VM. For 10k pcs, things are possible.

[lang...@fonz.dk]

sure anything is possible. I use an LCD controller with frame buffer, but;
having to implement a whole new framework to use the primitives instead of an existing portable one that paints directly to a frame bufferis a pain in the rear, an IC with +1MB sram isn't free, and the interface is slow compared
to a frame buffer in internal ram.

and you can't fit much fancy graphics in a 2MB flash

-Lasse

[edward....@gmail.com]

On Monday, September 8, 2014 9:04:04 AM UTC-7, lang...@fonz.dk wrote:
> Den mandag den 8. september 2014 16.48.09 UTC+2 skrev edward....@gmail.com:
> > On Monday, September 8, 2014 7:44:06 AM UTC-7, edward....@gmail.com wrote:
> > > > > > > > I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.
>
> > > > > > > It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.
>
> > > > > > I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ram, 4GB flash for 50$
>
> > > > > Yes, economy of scale.
>
> > > > > > if you buy parts and build something with a 7" lcd and capacitive touch yourself I'd think $50 is hard to meet, even with a single chip micro
>
> > > > > Doable for 10k pcs. You can get parts much cheaper than retail.
>
> > > > yes, but for anything "android fancy" 2M flash and 512K sram isn't nearly enough, even in a lowly 256 colors the frame buffer alone will take up 80% of the ram
>

> > You can get custom LCD controller with frame buffers. You can implement drawing primitives in the LCD controller, or even a Java VM. For 10k pcs, things are possible.
>
> sure anything is possible. I use an LCD controller with frame buffer, but; having to implement a whole new framework to use the primitives instead of an existing portable one that paints directly to a frame buffer is a pain in the rear, an IC with +1MB sram isn't free, and the interface is slow compared to a frame buffer in internal ram.

>
> and you can't fit much fancy graphics in a 2MB flash

I don't think the OP is interested in fancy graphics and/or video. It would be too slow on serial RS485 anyway. He is probably thinking about buttons, dropdown list, etc. If you limit the output to reasonable colors (e.g. 64), you can build the frame buffer with 128K sram. 64K sram LCD controllers are very common. 128K might be slightly more expensive, but much cheaper than external SDRAM.

SDRAM might not be too bad by itself. But the supporting circuit and CPU requirements drive up components and assembly costs.

[lang...@fonz.dk]

just because data is slow doesn't mean you can't use a lot of graphics to
display it

that low number of bits a limited resolution will have nothing like the
look or feel of an android tablet

-Lasse

[edward....@gmail.com]

> > > > > > > > > > I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.

> > > > > > > > > It would be difficult to meet the target price of $50. The Allwinner SoC still need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.
>
> > > > > > > > I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ram, 4GB flash for 50$
>
> > > > > > > Yes, economy of scale.
>
> > > > > > > > if you buy parts and build something with a 7" lcd and capacitive touch yourself I'd think $50 is hard to meet, even with a single chip micro
>
> > > > > > > Doable for 10k pcs. You can get parts much cheaper than retail.
>
> > > > > > yes, but for anything "android fancy" 2M flash and 512K sram isn't nearly enough, even in a lowly 256 colors the frame buffer alone will take up 80% of the ram
>
> > > > You can get custom LCD controller with frame buffers. You can implement drawing primitives in the LCD controller, or even a Java VM. For 10k pcs, things are possible.
>
> >
>
> > >
>
> >
>
> > > sure anything is possible. I use an LCD controller with frame buffer, but; having to implement a whole new framework to use the primitives instead of an existing portable one that paints directly to a frame buffer is a pain in the rear, an IC with +1MB sram isn't free, and the interface is slow compared to a frame buffer in internal ram.
>
> > > and you can't fit much fancy graphics in a 2MB flash
>
> > I don't think the OP is interested in fancy graphics and/or video. It would be too slow on serial RS485 anyway. He is probably thinking about buttons, dropdown list, etc. If you limit the output to reasonable colors (e.g. 64), you can build the frame buffer with 128K sram. 64K sram LCD controllers are very common. 128K might be slightly more expensive, but much cheaper than external SDRAM.
>
> just because data is slow doesn't mean you can't use a lot of graphics to display it
>
> that low number of bits a limited resolution will have nothing like the look or feel of an android tablet

You can get the look and feel without the background. Other than the background picture, Android only use a very small subset of colors. Except for loading custom picture buttons, you can't really assign arbitrary color schemes without very extensive custom modifications. Most apps only use the custom library of a few colors. Regarding colorful backgrounds, sometimes I turns them off because they are too distracting anyway. That's true for both my Android phones and laptops.

Of course, there is no absolute right or wrong. We are just offering two opposite opinions for the OP to pick and choose.

[Anders....@kapsi.spam.stop.fi.invalid]

pozz <pozz...@gmail.com> wrote:
> I could use just Linux and abandon the idea to use Android, but the
> question will be: is it possible to create the same or a similar
> look&feel with bare Linux? ...without spending too much time to reinvent
> and rewrite the same things already written in Android OS?

Have a look at eg. Qt.

-a

[embdev-design]

Hi pozz,

Even a micro with no build in LCD controller will do the job if you do not
need animation or other moving objects, and the system can be a industrial
grade design. Not sure about the enclosure requirements, but a single board
design can be achieved. We did a similar application with nice graphic and
touch feedback, but in lower quantities.

gabriel

>Il 07/09/2014 00:38, edward....@gmail.com ha scritto:
>>>> I need a very low-cost (50USD for quantity) touch panel running
Android OS. I'll use only the LCD, the touch panel and a serial interface
(RS485). A USB device port (to make a connection with a PC) and/or USB
host port (for connecting USB pen drives) would be nice. The size of LCD
could be from 5 to 7".
>>
>>>> I don't need SD, Ethernet, WiFi, CAN, RTC, battery, Bluetooth and
other
>>

>> Sound like you don't really need Android. You are spec'ing out
everything that need Android/Linux/networking.
>
>But I need a LCD with a touch screen.

>
>
>>>> The final application will be a HMI with good graphics and human
interactions (like on Android smartphones).
>>

>> Or just a good micro with touch screen LCD.
>
>This is interesting. Do you think I could reach the same or similar
>look&feel of Android without Android? Could you suggest an OS and
>graphics frameworks or libraries to use? Mostly for touch management?

>
>
>>> Do you think your price target is realistic? For $50 you will be hard
pressed to find a small tablet which is about your specs minus the RS-485
plus a few very low cost peripherals. I would think they way to go is to
find the lowest priced tablet you can and add a USB RS-485 adapter.
>>

>> Might be doable if qty is high enough. I am thinking perhaps in 10K
pcs.
>>
>
>Yes, the quantity will be about 5k/10k.
>



---------------------------------------
Posted through http://www.EmbeddedRelated.com

[Dennis]

Sorry to hijack this post but I am coming in late to this discussion..

I just bought a "Landfill Ready" low end Android for $43.04 at the local
Staples. The link is here
http://www.staples.com/Nobis-7-inch-8GB-Tablet/product_1052513#pr-header-back-to-top-link
It comes with an OTG cable so that the USB port can be used in host mode.

FDTI now provides Android drivers for their chips, see
http://www.ftdichip.com/Android.htm

As a proof of concept exercise I downloaded the FDTI serial terminal app
from the Google store.This uses the Android driver mentioned above. I
then attached a FDTI TTL-232R-3.3 cable between the Android and my
Beaglebone Black serial console header. Fired up the FDTI serial
terminal on the Android and reset the Beaglebone and got the Beaglebone
startup display on my new Android.

FDTI also makes an rs485 cable.
http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS485_CABLES.pdf

At unit prices it is a bit above your $50, but in quantity I suspect it
would be in your range - maybe do your own adapter using the FDTI chip
to get exactly the features you need.

Since this would use generic support you would be less dependent on a
particular Android model/supplier.

[Dave Nadler]

On Wednesday, September 10, 2014 4:30:19 PM UTC-4, Dennis wrote:
> FDTI also makes an rs485 cable.
> http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS485_CABLES.pdf

The FTDI datasheet says this cable uses FT232R, and says:
"The FT232R datasheet, DS_FT232R, is available at
http://www.ftdichip.com."

The link in the datasheet is broken.
The FT232R is missing from the product list on the FTDI web page.

Does this product exist?
I was wondering if it was usable for RS-485 multi-drop;
in particular, how does it handle direction-switching,
addressing, and speed requirements...

Anybody know if this is a viable solution?

Thanks,
Best Regards, Dave

[embdev-design]

A typical RS232 to RS485 interface will switch the direction based on the
slave side traffic, by default being listening to the master (tablet). It
will switch back after a short delay (equivalent of 3 characters) after the
slave ends the transmission. The speed affects only the 3 characters delay
timer.

Gabriel

[edward....@gmail.com]

On Wednesday, September 10, 2014 2:17:46 PM UTC-7, embdev-design wrote:
> A typical RS232 to RS485 interface will switch the direction based on the slave side traffic, by default being listening to the master (tablet). It will switch back after a short delay (equivalent of 3 characters) after the slave ends the transmission. The speed affects only the 3 characters delay timer.

But who's the master and who goes first? You don't necessary want to be the master just because you have a screen. You could be attaching as a slave or just a monitor station. There are lots of settings and interaction between your app, os and low-level driver. Configurations might depends on what app you are running. Working around Android might not be easy. Your work around could easily overwhelm whatever you gain from using the stock COTS Android.

[Dennis]

On 09/10/2014 03:44 PM, Dave Nadler wrote:
> On Wednesday, September 10, 2014 4:30:19 PM UTC-4, Dennis wrote:
>> FDTI also makes an rs485 cable.
>> http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS485_CABLES.pdf
>
> The FTDI datasheet says this cable uses FT232R, and says:
> "The FT232R datasheet, DS_FT232R, is available at
> http://www.ftdichip.com."
>
> The link in the datasheet is broken.
> The FT232R is missing from the product list on the FTDI web page.

http://www.ftdichip.com/Products/ICs/FT232R.htm
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

>
> Does this product exist?
> I was wondering if it was usable for RS-485 multi-drop;
> in particular, how does it handle direction-switching,
> addressing, and speed requirements...

No idea I have never done RS-485

[Dennis]

There is an example of an RS485 converter on page 28 of the data sheet.

http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

I have no idea if this is any good or answers your question. I haven't
ever used RS-485

[Anders....@kapsi.spam.stop.fi.invalid]

Dave Nadler <d...@nadler.com> wrote:
> The FT232R is missing from the product list on the FTDI web page.

<http://www.ftdichip.com/Products/ICs/FT232R.htm>

-a

[Dave Nadler]

On Wednesday, September 10, 2014 7:50:44 PM UTC-4, Dennis wrote:
> http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

Thanks Dennis, I gave up as its not listed on FTDI's summary product page...

Anyway, the FT232R datasheet says it can only do 7 or 8 data bits.
If that's so, this part will not work for lots of RS-485
networks that use 9-bit addressing...

IIRC Exar has parts that do this (but no Android drivers).

OP was not specific in his RS-485 requirement!
He might be best off building a small dongle
that does USB to the host with vanilla CDC,
with the dongle implementing the specific RS-485
protocol as he requires. This would allow
easier integration with hosts not able to meet
timing requirements etc; I've done similar...

Hope that helps,
Best Regards, Dave