LCD JLX12864 flashing

[m-feddersen]

When I start the pypilot it shows the graph and version 0.24.
After that nothing is displayed. If I exit the Pypilot via the console, the data is briefly displayed again. What can be the reason?

[Onno]

I have the same problem, all the displays produced after 2021-09-08 have the same problem, I have contact support from my agent in China with JLX but we are not able to find the problem yet.

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Sorry maybe slightly different, all displays flicker/flash (characters not backlight)

[m-feddersen]

I have the same problem, all the displays produced after 2021-09-08 have the same problem, I have contact support from my agent in China with JLX but we are not able to find the problem yet.

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Sorry maybe slightly different, all displays flicker/flash (characters not backlight)

But that can't be a fault of the display. if I do a reboot via the console, everything is clear on the display until the kill command is finished. (See pictures)

[seandepagnier]

what exact sequence did you use and what did you kill?

I might be able to explain it but I dont know what you did.

[Onno]

Video from my problem: https://photos.app.goo.gl/XkqvAokpB6mF9gcA8

[Onno]

We have also tested them with a scope, the only difference we see is on pin12 CS, on the good display it is a nice constant signal and on the bad one it is not constant.

    Good Display

    Bad display

[seandepagnier]

The different CS in the scope is very strange because the raspberry pi drives it, not the display.

Is there any way to tell the good from bad display by markings on the board or only from testing?

[Onno]

Only the flat cable from display itself is a little different, and production data I have not seen a display working yet from 2022.
   

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The only response from JLX so far: He suggest that when you edit the data and instruction, try to extend the program delay. 
I do not know what that means.

[stelian]

Hi Onno,

Strange behaviour.

Some ideas: try lower the SPI frequency (in hat/ugfx/ugfx.cpp, try changing the default frequency of 1000000 Hz to something lower)

In the same file, you will see a few "write(spifd, cmd, sizeof cmd)", surounded by digitalWrite (dc, LOW) / digitalWrite (dc, HIGH). You can try adding some delays (using usleep(1000) for example for 1ms) somewhere here, after the write(spifd) and before digitalWrite(HIGH), or after the digitalWrite(HIGH), you need to play a bit with it to find out if that improves somehow the behaviour.

It could also be that something else changed...

[seandepagnier]

well I certainly can reproduce it, and thanks for pointing out the difference.

I received some new jlx12864 a few days ago and they are all the new style and have this problem.

I will try to debug/improve the driver and find a solution