Very low-cost Android-based touch panel for HMI

On 9/7/2014 4:45 PM, langwadt@fonz.dk wrote:
> Den s�ndag 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
>
@Lasse

Please post which store you have found this tablet.

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

Correct ?

Il 08/09/2014 00:24, Dave Nadler ha scritto:
> 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)

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.

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

>Il 08/09/2014 00:24, Dave Nadler ha scritto:
>> 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)
>
>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.

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.
 

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

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

> 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?

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

Den mandag den 8. september 2014 05.25.57 UTC+2 skrev hamilton:
> On 9/7/2014 4:45 PM, langwadt@fonz.dk wrote:
> 
> > Den s�ndag 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
> 
> >
> 
> @Lasse
> 
> 
> 
> Please post which store you have found this tablet.
> 
> 
> 
> By store you mean something local to you home country, with out shipping ?
> 
> 
> 
> Correct ?

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

Den mandag den 8. september 2014 02.01.14 UTC+2 skrev edward....@gmail.com:
> On Sunday, September 7, 2014 3:45:58 PM UTC-7, lang...@fonz.dk wrote:
> 
> > Den s�ndag 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.

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

> > > > > 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 

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
(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.

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
> 
> (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.

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