0

SHARP Memory Display Breakout pins and Refresh
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

SHARP Memory Display Breakout pins and Refresh

by darksheep on Tue Jul 16, 2013 11:16 am

:?: Hi

I bought your sharp Display and I am very happy with it and your packaging !!! Got to me all the way in South Africa safely.
I just have a few questions.

Question 1

This section of code is in the example,Is it necessary to refresh the screen once a second ?
If I don't refresh the screen and leave the text on the screen will it damage the screen ?

Code extract from sharpmemtest.ino

Code: Select all | TOGGLE FULL SIZE
void loop(void)
{
  // Screen must be refreshed at least once per second
  display.refresh();
  delay(500);
}


Question 2

What are the other pins for on the screen in your example you only use VIN,GND,CLK,DI,CD.
So what do 3v3,EMD,DISP and EIN do and how can I use them ?
I also what to point out you say in CD for one pin in your tutorial but it is actually labeled CS on the screen.

Question 3

Your tutorial mentions displaying simple animations using bitmaps but there is no clear example of how to do this or may be I am confused,please could you elaborate ?

Thank you for you time and truly innovate products and company !!!!

darksheep
 
Posts: 15
Joined: Tue Nov 06, 2012 9:13 am

Re: SHARP Memory Display Breakout pins and Refresh

by adafruit_support_bill on Tue Jul 16, 2013 11:44 am

Thanks for the feedback. The CS/CD typo is fixed.

Page 4 of the data sheet discusses the need to refresh to avoid damage to the display, but the period is much longer than one second: http://www.adafruit.com/datasheets/LS01 ... 204284.pdf

The 3v3 pin is the output of the 3.3v regulator on board.
The EMD, DISP and EIN pins are breakouts for EXTCOMIN, DISP & EXTMODE as described on page 8 of the datasheet.

Bitmap drawing can be done using the GFX library. The guide for that is here: http://learn.adafruit.com/adafruit-gfx- ... primitives
I don't believe we have any example code for animation yet.

adafruit_support_bill
 
Posts: 74058
Joined: Sat Feb 07, 2009 10:11 am

Re: SHARP Memory Display Breakout pins and Refresh

by darksheep on Tue Jul 16, 2013 1:41 pm

Ok thanks , I see they say "3) A still image should be displayed less than two hours, if it is necessary to display still image longer than two hour,
display image data must be refreshed in order to avoid sticking image on LCD panel.
"

So that seems like quite some time,may be you should place a note in the example for others - just a suggestion.

Do you know how I would send a signal to turn the display on and off using the DISP pin?

darksheep
 
Posts: 15
Joined: Tue Nov 06, 2012 9:13 am

Re: SHARP Memory Display Breakout pins and Refresh

by task on Mon Jul 29, 2013 11:42 pm

darksheep wrote:Do you know how I would send a signal to turn the display on and off using the DISP pin?


I assume you connect a pin to disp and pull it low. Reading the document it seems when they talk about "H" it is HIGH and when they talk about "L" it is LOW. It is probably HIGH by default at the moment. I am also going to start playing with this today or tomorrow
task
 
Posts: 18
Joined: Sun Nov 11, 2012 9:30 pm

Re: SHARP Memory Display Breakout pins and Refresh

by darksheep on Tue Jul 30, 2013 2:18 am

Ok cool thanks let me know how you go :)

darksheep
 
Posts: 15
Joined: Tue Nov 06, 2012 9:13 am

Re: SHARP Memory Display Breakout pins and Refresh

by task on Fri Aug 02, 2013 8:49 am

darksheep wrote:Ok cool thanks let me know how you go :)

Dit gaan lekker :)
task
 
Posts: 18
Joined: Sun Nov 11, 2012 9:30 pm

Re: SHARP Memory Display Breakout pins and Refresh

by mrstew on Sun Dec 31, 2017 3:28 pm

I know this is an old thread, but adding 2c because it confused me at first when I came across it via Google :)

I think the display refresh every second comment is to do with the COM inversion signal rather than any screen burn in - by default this is done in software and the Adafruit library handles it here:

https://github.com/adafruit/Adafruit_SH ... m.cpp#L289

The datasheet is a bit vague on this point, I'm going on some blurb for a different breakout board:

"Memory LCDs require a regular polarity inversion of the voltage across the LCD panel to prevent latent charge building up. The recommended frequency of this inversion is from 1-60 Hz and it is the EXTMODE and EXTCOMIN pins that control/provide the source of the signal that instructs the panel to invert its polarity."

http://www.makerdyne.com/blog/tag/sharp-memory-lcd/

If you don't call refresh() at least once a second my understanding from the above is that you need to pull EMD high and ping the EIN pin instead at anywhere between 1Hz and 60Hz.

mrstew
 
Posts: 14
Joined: Mon Dec 19, 2016 1:20 pm

Re: SHARP Memory Display Breakout pins and Refresh

by dc443 on Fri Aug 09, 2019 3:47 pm

Has anybody used the CircuitPython Sharp Memory display library for use on a Pi?

I do see the VCOM inversion code in there. So hopefully it'll just work. But I worry about the duration between poweron and the application running, and also if any software crashes and the power remains supplied, it would damage the screen...

dc443
 
Posts: 18
Joined: Mon Apr 12, 2010 1:38 am

Please be positive and constructive with your questions and comments.