Newhaven Display Forum

Newhaven Products => TFTs => Topic started by: asfarley on December 07, 2018, 10:47:27 AM

Title: Filling with blue yields flashing white screen (NHD-2.4-240320CF-CSXN#-F)
Post by: asfarley on December 07, 2018, 10:47:27 AM
Hi,

We're using NHD-2.4-240320CF-CSXN#-F on a new product. I'm just getting started writing the basic driver.

I'm experimenting with writing solid R/G/B blocks to the screen, and I've noticed a few strange effects:

 * If I fill the entire screen with red or green, it works as expected; if I attempt to fill the entire screen with blue in one shot, the end result is a flashing white image
 * If I fill the screen incrementally with blue (in full-screen-width, 10-pixel-high blocks, step-by-step) then the screen appears completely blue, as expected
 * If I fill the screen with blocks in the order R/G/B (1/3 of the screen is red, 1/3 is green, 1/3 is blue) then I get the flashing-white-screen effect
 * If I fill in the order B/G/R, then I get the correct image
 * Most of the time, while the write operation is in progress, the entire image flashes white
 * I have seen some instances where the screen did not flash white between write operations; not sure what was different in that scenario

Are these phenomena familiar to anyone here?

It feels a bit like blue pixels consume more power, and I'm running into a power-stability issue by setting the entire image blue in one-shot, whereas maybe incremently updating to a 100%-blue image is easier on the power supply. Is that possible? Or is something else going on here?
Title: Re: Filling with blue yields flashing white screen (NHD-2.4-240320CF-CSXN#-F)
Post by: asfarley on December 10, 2018, 11:01:51 AM
It turns out that this was related to an entirely separate issue; our PCB was experiencing some power-stability issues due to a misconfigured GPIO on our MCU. After fixing that, all of this weird flashing-screen behavior disappeared.
Title: Re: Filling with blue yields flashing white screen (NHD-2.4-240320CF-CSXN#-F)
Post by: Paul_B on December 11, 2018, 07:17:54 AM
Glad to hear you got your display up and running!

Thanks for sharing your solution, it will definitely help others  :D