Waveshare e-paper display not showing good red colour - Page 1
Forum section: electronics / projects

author: Amper
author_rank: Frequent Contributor
timestamp: March 22, 2020, 09:50:06 am
content: 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.pdfIm using this lib for control:https://github.com/ZinggJM/GxEPDBlack 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...

author: Miyuki
author_rank: Frequent Contributor
timestamp: March 22, 2020, 10:32:18 am
content: Have it any analog adjust or voltage test points ?This color are very sensitive to even slightest changes in voltage, current and timingLike color passive matrix lcd screens, all pixels interact with neighboring ones and you working with minuscule charges levelsSomewhere was comparison that it is like playing chess with 5 meters long sticks

author: Amper
author_rank: Frequent Contributor
timestamp: March 22, 2020, 11:19:39 am
content: 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.

author: Miyuki
author_rank: Frequent Contributor
timestamp: March 22, 2020, 12:35:31 pm
content: Black and white is simple to workBut colors are in the middle and it must hit that exactly spot, that is tricky

author: Amper
author_rank: Frequent Contributor
timestamp: March 22, 2020, 01:15:28 pm
content: Mh, thats true, but i dont see how i could effect that?

author: Skashkash
author_rank: Regular Contributor
timestamp: March 22, 2020, 01:16:42 pm
content: 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-introductionquick edit, Ben has a great video on e-ink displays

author: Amper
author_rank: Frequent Contributor
timestamp: March 22, 2020, 03:51:30 pm
content: I know this vid, it introduced me to the tri colour ones back then.https://forum.arduino.cc/index.php?topic=641272.0this may be helpful.

author: Amper
author_rank: Frequent Contributor
timestamp: March 22, 2020, 04:29:29 pm
content: 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.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 17, 2020, 02:30:56 pm
content: Does anyone here have experience with "E-Paper" stuff?I would need "just" a external E-Paper Display to show some quite Static Stuff.

author: Amper
author_rank: Frequent Contributor
timestamp: May 19, 2020, 06:01:02 pm
content: I sort of do by now, whats your problem exactly?