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Hi Sir,

Could you provide some suggestion on the issue of color gradients?

  • Profile Configuration:

 

  • Color gradients for testing as below:

group 1 has 4 colors at 4 corners

group 2 is in Vertical

group 3 is in horizontal

  • The setting for group 1 as reference, snapshot from EmWi studio:

Thanks.

Jerry

1 Answer

0 votes
by

Hi Jerry,

this seems to be more a hardware problem - please check all RGB lines between the MCU and the display.

Can you please make a test with three horizontal gradients, each with black to white color. The first with width = 256 pixel, second with width = 480 pixel and third with width = 512 pixel (which does not fit into the display, but no problem).

How does the result appear on your target?

Best regards,

Manfred.

by

Hi Manfred,
Many thanks to you.
Please see these pic below.

Thanks

Jerry

by
Hi Jerry,

thank you for the provided images. As you can see, all three gradients have the same pattern (the same vertical lines) at the same color value. Because they have a different width, the x position is different.

Therefore, I assume that the problem is not related to some timings or clock settings.

The following issues could cause the problem and should be checked:

* Hardware connection between MCU and Display. Maybe there is a wire missing, changed, connected with another wire...

* GPIO is not initialized correctly or used by another software component.

Btw: Is your display connected as RGB565 (16bit), RGB666 (18bit) or RGB888 (24bit)?

What you can do: Make three rectangles (one for red, one for green and one for blue), then use a very slow effect to change the color of each rectangle from 0x00 to 0xFF for each color channel (R,G,B). Print the color values somewhere on the screen. With this test it should be possible to detect the color values which causes a wrong output. Then we can nail down the wrong pins.

Best regards,

Manfred.
by

Hi Manfred,

I have followed your suggestion to make some testing.

3 Color gradients, Red, Green and Blue with 0 to 255 color level changing per 1 second.

Sample pictures as below to show the different color level to comfirm I did the right testing.

For all the steps of 0 - 255, none of pic shows the bright line as before.

For connection check, I will ask Hardware team to check.

Conld you have any comments for the testing?

 

Jerry

by
Hi Jerry,

did you notice some non-linearity? Was there any resulting colored rectanlge that does not correspond to the value?

Manfred
by
Hi Manfred,

It is difficult to distinguish whether there is a difference between two consecutive colors, because the color levels differ by only 1. No sudden change in color was found.

Do you have further idea on this?

Also, we will check our hardware, LCDIF port, setting and LCD driver.

Thanks.

Jerry
by
Hi Jerry,

if there is no non-linearity, it seems that the wiring is in principal fine.

However, after thinking once more about the graphical results on your LCD - the remaining idea is electrical shielding.

Is it possible, that there is some crossover in the datalines?

Best regards,

Manfred.
by
Hi Manfred,

No corssover is in the datalines.

A FPC is used to connect main board and LCD module( include touch screen).

Thanks

 

Jerry

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