Very low-cost Android-based touch panel for HMI

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.

Den mandag den 8. september 2014 18.18.48 UTC+2 skrev 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.  
> 
> 

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

> > > > > > > > > > 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.

pozz <pozzugno@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

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.ming.lee@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

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

On 09/10/2014 12:20 PM, embdev-design wrote:
> 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.ming.lee@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.
>>

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.

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

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

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

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

>
> Anybody know if this is a viable solution?
>
> Thanks,
> Best Regards, Dave
>