Author Topic: Waveshare e-paper display not showing good red colour  (Read 1329 times)

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Offline AmperTopic starter

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Waveshare e-paper display not showing good red colour
« on: March 22, 2020, 09:50:06 am »
Hi!

I just started playing with a "1.54 inch e-Paper" display module from waveshare, 200x200px b/w/r.

https://www.waveshare.com/w/upload/e/e5/1.54inch_e-paper_V2_Datasheet.pdf

Im using this lib for control:

https://github.com/ZinggJM/GxEPD

Black works beautifully, but the red colour is nothing like the images i found, not only in ads but also non commercial videos.
Its very pale, in the best case orange, very very bad contrast to the backround.

Can i do anything wrong controlling it or is it a faulty display?
afaik its supposed to handle all the updating internally so i would be surprised...
 

Offline Miyuki

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Re: Waveshare e-paper display not showing good red colour
« Reply #1 on: March 22, 2020, 10:32:18 am »
Have it any analog adjust or voltage test points ?
This color are very sensitive to even slightest changes in voltage, current and timing

Like color passive matrix lcd screens, all pixels interact with neighboring ones and you working with minuscule charges levels
Somewhere was comparison that it is like playing chess with 5 meters long sticks
 

Offline AmperTopic starter

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Re: Waveshare e-paper display not showing good red colour
« Reply #2 on: March 22, 2020, 11:19:39 am »
Mh, sadly no adjustment, at least in hardware. The Supply is done by an onboard buck from 5V to 3.3V and since black works bautifully i guess thats not the issue.

I just tried heating it a bit to change the viscocity but that also doesnt seem to make a difference.
 

Offline Miyuki

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Re: Waveshare e-paper display not showing good red colour
« Reply #3 on: March 22, 2020, 12:35:31 pm »
Black and white is simple to work
But colors are in the middle and it must hit that exactly spot, that is tricky
 

Offline AmperTopic starter

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Re: Waveshare e-paper display not showing good red colour
« Reply #4 on: March 22, 2020, 01:15:28 pm »
Mh, thats true, but i dont see how i could effect that?
 

Offline Skashkash

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Re: Waveshare e-paper display not showing good red colour
« Reply #5 on: March 22, 2020, 01:16:42 pm »
You may be using the wrong drive waveform.

The actual E-ink panels are very sensitive to the drive waveform used to set and clear "pixels".
The differing waveforms to use for each action and color is programmed into the e-ink controller from firmware tables.
The waveform tables differ from display to display, and are also somewhat temperature dependent.

So, not all waveform tables are created equal. You may be using the wrong waveform tables.     

Maybe some additional info here,
https://hackaday.io/project/21168-fpga-eink-controller/log/57302-waveforms-table-introduction


quick edit, Ben has a great video on e-ink displays

« Last Edit: March 22, 2020, 02:24:01 pm by Skashkash »
 

Offline AmperTopic starter

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Re: Waveshare e-paper display not showing good red colour
« Reply #6 on: March 22, 2020, 03:51:30 pm »
I know this vid, it introduced me to the tri colour ones back then.

https://forum.arduino.cc/index.php?topic=641272.0 this may be helpful.
 

Offline AmperTopic starter

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Re: Waveshare e-paper display not showing good red colour
« Reply #7 on: March 22, 2020, 04:29:29 pm »
Wellllllll.....

Since i didnt buy thi think myself i now have the creeping thought the display may be totally allright...

Its not a B/W/R but a B/W/Y version, after having displayed stuff in lager areas and with black backround i can see that the contrast is actually nice, its just not red as expected and the orangy yellow is almost the same colour as the "white" backround on small features.
 

Offline Lord of nothing

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Re: Waveshare e-paper display not showing good red colour
« Reply #8 on: May 17, 2020, 02:30:56 pm »
Does anyone here have experience with "E-Paper" stuff?
I would need "just" a external E-Paper Display to show some quite Static Stuff.
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline AmperTopic starter

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Re: Waveshare e-paper display not showing good red colour
« Reply #9 on: May 19, 2020, 06:01:02 pm »
I sort of do by now, whats your problem exactly?
 


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