4.41 inch ePaper Display for the rPi - Page 2

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Re: 4.41 inch ePaper Display for the rPi
On 7/29/2015 5:26 AM, snipped-for-privacy@isbd.net wrote:
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That is an e-paper display for sure then.  I'm surprised they included  
this display in anything other than a book reader.  So much of what a  
tablet or PDA does requires faster drawing times.

Wait until you try to use it in cold weather.  They slow down a *lot*.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
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I'm rather unlikely to use it in the cold! :-)

It's promoted mainly as an e-reader but with the advantage of being
much more 'open' than the proprietary Kindle etc.  I bought it for its
openness, it means I can read Amazon Kindle books *and* ePub books
from my public library (and for that matter other proprietary formats).

--  
Chris Green


Re: 4.41 inch ePaper Display for the rPi
On 7/29/2015 4:21 PM, snipped-for-privacy@isbd.net wrote:
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I assume you can also run your own code on it?  I've never been clear on  
just how open Android devices really are.  I don't have one of my own,  
but maybe it is only the Android cell phones that aren't very open.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
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You'd have to root it, as delivered Android isn't open like a Linux
installation.  Android on a tablet is near enough the same as Android
on a smartphone, one of its advantages in a way.

--  
Chris Green


Re: 4.41 inch ePaper Display for the rPi
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To install a user developed Android application, you don't need to root
it.  This is different from an iPhone.  An Android device can be configured
to install packages from .apk files or from user defined app stores.

Of course an Android application has no full control over the system, that
is where the rooting comes in.

Re: 4.41 inch ePaper Display for the rPi
On 30/07/15 10:23, snipped-for-privacy@isbd.net wrote:
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I run my own app on my Android phone. I compile the .apk file on my  
Linux PC using ant and then upload to the USB connected phone using adb.

The phone needs to have the developer options enabled, but that is a  
simple option and doesn't "root" Android in any way.


Re: 4.41 inch ePaper Display for the rPi
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Yes, you're both quite right of course.  It's easy enough to install
an app you have written yourself on an unrooted Android device.  I was
rather thinking of doing the development on Android in the same way I
develop on Linux.

--  
Chris Green


Re: 4.41 inch ePaper Display for the rPi
I found this on the Kobo.

Kobo Aura features a beautiful edge-to-edge design and is equipped with  
ClarityScreen, a low-glare 6? HD Pearl E Ink screen boasting a stunning  
1014 x 758 resolution for a print on paper reading experience even in  
direct sunlight.

They have a video showing use of a magnifying function on the display.  
The small window for setting the zoom is a partial update and so is  
faster.  But when the entire display updates you can see it happen and I  
think it takes maybe 300 - 400 ms.  If you used a 1 second refresh on  
the entire screen it would flash pretty badly I think.  Use a partial  
update and you can make it work pretty well.

This points to another short coming in the ePaper info.  What is  
different about the displays used in eReaders and the displays Pervasive  
sells?

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
On Fri, 19 Jun 2015 17:43:50 -0400, rickman wrote:

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Might the Kobo use a faster, more capable controller?  

I wonder how much the update speed is affected by the transfer rate.  

Off the top of my head, if you're sending every pixel down an SPI  
connection uploading changes to the controller will be relatively slow,  
but IIRC pixel flipping is a physical process, and so is also pretty  
slow. I'd guess a cheap bit-serial controller would be rate-limited by  
pixel flipping rather than the SPI transfer rate, but what do I know. A  
full refresh on that 2.7" display is taking about 30 uS to set a pixel,  
so how does that compare with normal SPI transfer rates?

Would I be wrong to expect a more complex and expensive controller, which  
might accept byte-wide uploads over some sort of parallel interface,  
could speed up the overall refresh by flipping several pixels in parallel  
or at least double buffer the uploads so it could accept uploads in  
parallel with pixel flipping.
  

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martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: 4.41 inch ePaper Display for the rPi
Sorry if this has been suggested.

How about hacking the original Kindle w/ paper white display.

http://hackaday.com/category/kindle-hacks/


Re: 4.41 inch ePaper Display for the rPi
On 6/19/2015 7:58 PM, Martin Gregorie wrote:
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I can assure you the limitation has nothing to do with the controller.  
It has to be in the display as it would be very easy to design a  
controller that would be *much* faster than a 1 second update.  The HDMI  
interface you mention supports 60 Hz updates at full HD resolution.  
That's just not the limitation.


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Why?  There are 120,000 pixels.  At 20 MHz the SPI can support 166  
updates per second.


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None of this is a controller limitation.  That is all determined by the  
display.  I don't know for sure, but I think the larger displays are  
divided into multiple sections that work in parallel.  Otherwise the 10"  
display would be more than four times slower than the 4.41" display.  
The 7 and 10 inchers even have two connectors.

No point in speculating.  If I can't get the info on rolling my own  
controller, I am probably drop the ePaper thing for another couple of  
years until they get their act together.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
On Fri, 19 Jun 2015 22:44:00 -0400, rickman wrote:

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You asked about the Kobo refresh rate. Here's a video of one, illuminated  
by direct sunlight and running LK8000, which is news to me since I didn't  
know it had been ported yet.


https://www.youtube.com/watch?v=Lxojrs4f2I4


I tried timing it with a stopwatch but found it quite difficult to get  
accurate times off the video. All I can say is that a whole screen  
refresh is comfortably under 0.5 secs and scrolling through configuration  
settings is a lot faster than that.


--  
martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: 4.41 inch ePaper Display for the rPi
On 6/20/2015 7:18 AM, Martin Gregorie wrote:
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I think that is faster than the update I saw at the Kobo site.  So less  
than 300 ms.

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I would say this is usable for any app other than a video type function.  
  Next time I speak with the salesman from Pervasive, assuming he speaks  
to me again, I will ask why the huge discrepancy in update rates.  I  
expect I am flying below their radar since I won't be buying 100,000 a  
year.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
Another one with just the touch screen.

http://www.good-display.com/products_detail/&productId30%1.html

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
On Thu, 18 Jun 2015 21:36:17 -0400, rickman wrote:

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Neat, but far too big for me; I could just squeeze in a 4.2" landscape  
display, but there just isn't enough room on or in front of my panel.
Here's a pic of the full panel with a Binatone B.350 (3.5" display)  
mounted and running:

http://www.gregorie.org/gliding/libelle/FLARM_panel.jpg

My current PNA, the Medion S3747, is an almost identical size.


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martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: 4.41 inch ePaper Display for the rPi
On 6/19/2015 7:45 AM, Martin Gregorie wrote:
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Notice that both devices have a huge border around the display.  You can  
use a larger display if you get one that is wall to wall display.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
On Fri, 19 Jun 2015 13:17:48 -0400, rickman wrote:

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Agreed, but you only seem to find narrow borders on the larger displays.  
I have no idea why this is the case, but narrower borders only start on  
some of the devices with 4.2" screens. Putting numbers on it that Binatone  
B.350 is 4.7" on the overall diagonal. I know that I can get away with  
using a 4.2", narrow bordered screen but those have recently turned into  
unobtanium.  

A couple of years back a very narrow bordered 5" device appeared on the  
market, so I made a cardboard frame for the Binatone with its dimensions  
to check it out. It didn't look very much bigger, but mounting that on  
the panel soon showed that it was too big: it hid more of the vario at  
top right than I was happy with and it extended sideways far enough to  
encroach on the radio at lower centre.
  

--  
martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: 4.41 inch ePaper Display for the rPi
On Thu, 18 Jun 2015 11:42:27 -0400, rickman wrote:

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Have you seen these?

http://www.lancom.de/fileadmin/produkte/lc_wireless_epaper_displays/
LANCOM-Wireless-ePaper-Displays-EN.pdf

I found this from a search for 4.4" displays: it seems to be the 4.4"  
display in a plastic case with a battery and radio link. Is it any use to  
you?

The size and resolution are almost exactly what I'd want, but I can't use  
it because the refresh rate is too low at 3000/hour, i.e. 1.2 secs per  
refresh and its only bicolour (black and white - no grey scale).


--  
martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: 4.41 inch ePaper Display for the rPi
On 6/20/2015 10:23 AM, Martin Gregorie wrote:
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These sound like the same Pervasive displays we've been talking about.  
I'd suggest you go with the Kobo.

These are of no value to me.  I'm looking for a bare display I can roll  
into my own product which has very different requirements from these  
devices.  I need extended temperature and Ethernet comms.

They must have a pretty hefty battery to last 5 years even with just 4  
updates per day.  The radio likely uses more juice than the display.

--  

Rick

Re: 4.41 inch ePaper Display for the rPi
On 6/18/2015 11:42 AM, rickman wrote:
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I got the final word back from Pervasive Displays and while they offer  
an extended temperature range display, they have no extended temperature  
controller for the larger units and are not willing to provide interface  
specs so you can roll their own.

You gotta wonder what they are thinking...

--  

Rick

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