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HXD8357 TFT white screen
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Please be positive and constructive with your questions and comments.

HXD8357 TFT white screen

by controlfreaks on Tue Dec 05, 2017 7:13 pm

I have successfully (almost) been using the 3.5" tft. (product: 2050). I have written all my own drivers and graphics routines (as close as I can to Adafruit's) for a PIC micro using SPI. I have also written entirely my own routines for the resistive touch screen. The TFT displays a menu tree for controlling a piece of equipment.

The problem I am having is every once in a while the screen will just go white and will be unresponsive until I reset it. This always happens after a press on the screen but very intermittent. If I am constantly pressing buttons the screen, it could happen within a couple of minutes or it could take 30 minutes. (a few dozen taps on the screen or a few hundred).

The very intermittent nature of the fault makes me think it is a noise issue but that is only a theory. I have changed out the ribbon cabling I was using for shielded cable but the fault still persists.

I have the usual decoupling caps across the power supply. My reset pin is tied high.

Any thoughts as to why I am having this problem would be appreciated.



Cheers,
James

controlfreaks
 
Posts: 13
Joined: Wed Mar 16, 2016 2:01 pm

Re: HXD8357 TFT white screen

by amarch on Wed Dec 06, 2017 6:22 pm

I have had a similar problem. It has to do with faulty SD card holders and I've found it to be the case with over 20% of the screens.
You can see it in my post here.
I haven't heard back from them on this topic but it's not very good to have such a high failure rate. I have not received any response and can only conclude that they have no protocol for addressing this issue.

amarch
 
Posts: 5
Joined: Mon Nov 27, 2017 3:56 pm

Re: HXD8357 TFT white screen

by controlfreaks on Wed Dec 06, 2017 8:49 pm

Thanks for the reply amarch,

I am sorry you are having problems with the SD card slots. I do not, however, see the connection to my screen going white. If there is connection it might lead to a solution,am I missing something?

Cheers,

James.

controlfreaks
 
Posts: 13
Joined: Wed Mar 16, 2016 2:01 pm

Re: HXD8357 TFT white screen

by controlfreaks on Tue Dec 12, 2017 6:30 pm

So I have found the issues to my problems, and although specific to my code, could help people in the future so I will share it.

It turned out my pressing of the screen was casing a interrupt conflict whilst writing to the display. The intermittent nature was tricky because the 'bad luck' stars had to align for the fault to occur.

The fix was obvious, disable all pertinent interrupts just before writing to the display and then re-enable them again.

Rookie mistake, too bad I'm not really a rookie; just easily distracted.

Hope this may help someone in the future.

Cheers

James

controlfreaks
 
Posts: 13
Joined: Wed Mar 16, 2016 2:01 pm

Please be positive and constructive with your questions and comments.