2.8 inch tft shield white screen
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2.8 inch tft shield white screen

by urthlight on Fri Mar 22, 2013 12:03 pm

I bought 2 of these screens and built a piece of equipment around it. The unit is sweet and fairly easy to use. Gone through the testing process allis well it seems. But we had a white screen incident while testing but it cleared up after a power cycle. Well it has happened again several times. The machine is coming back I will swap the screens and see if it clears it up. Any insight or advice would be welcomed.
TYIA
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Re: 2.8 inch tft shield white screen

by Jim Lee on Fri Mar 22, 2013 1:22 pm

I've seen this with a memory overwrite error. Loose pointer somewhere in code.

-jim lee
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Re: 2.8 inch tft shield white screen

by pburgess on Fri Mar 22, 2013 1:26 pm

Hi there,

We've had a few instances of this, probably stemming from overzealous library optimization. If the version of the library you downloaded is more than a few days old, please fetch the latest from Github and see if that clears it up.

Let me know if that helps -- or, if not, if it only affects one board or both.
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Re: 2.8 inch tft shield white screen

by urthlight on Fri Mar 22, 2013 1:40 pm

I will do the swap first in order to cause the least changes. If that does not fix it I will look at changing the library. The one I am using is a couple of months old.
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Re: 2.8 inch tft shield white screen

by urthlight on Mon Mar 25, 2013 2:24 pm

Ok, Both displays are doing the same thing. So it is not hardware. Which is what I thought because I never saw this on the simulator machine that I have on the bench.
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Re: 2.8 inch tft shield white screen

by urthlight on Wed Apr 03, 2013 4:18 pm

All right I have the unit in house again. There are 3 pumps that run forward to fill and reverse to drain (dc motor 24 volt) an agitator motor (24 volt dc) All of the 24 volt stuff comes from a separate power supply switched by opto-solated relays. A 5 volt supply provides power for all of the electronics. The (-) sides of both supplies are bonded to the chassis. The white screen always happens during a mode change. I was thinking I was seeing EMF on the 5v power supply during start/stop of a dc motor. And indeed there are still tiny spikes on the electronics power bus even after attempts to mitigate with caps and ferrite beads. However I went to the manual drain page and hammered the pumps p1 then p2 then p3 and then p2 and then p1 .... rapidly, you get the idea, well anyway no white screen but when went back to another screen started an automatic mode the screen goes white when pump 2 starts. The white screen happens randomly. Sometimes in auto some times in manual some times during fill sometimes drain.

Any thoughts?
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Re: 2.8 inch tft shield white screen

by pburgess on Wed Apr 03, 2013 5:27 pm

Curious! Sounds almost like a brownout/power supply issue.

Could you try making a simple test program that accesses the display but never actually starts any pumps? Then start and restart and restart it many times until you either see a white screen or are confident the issue isn't happening. If the latter, now change the program to start one of the pumps and do the repeating test, see if it occurs.

Is the 5V a totally separate supply, or is it running from a regulator off the 24V source?

Also, I'm curious if this white screen is happening because the Arduino is resetting, or if it's happening in the middle of program execution. If you have a spare pin on the Arduino, could you set up an LED that's enabled at the very start of the sketch, and then gets turned off once the main loop is underway? That might help diagnose if it's a full glitch/restart or something else.

Finally...if the second test program described above (run screen and one pump) runs without incident, but the full program has this issue sometimes, I'd start to suspect the program is running out of RAM.
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Re: 2.8 inch tft shield white screen

by urthlight on Thu Apr 04, 2013 11:07 am

New wrinkle. Today I got a white screen in the middle of a drain.

Could you try making a simple test program that accesses the display but never actually starts any pumps? Then start and restart and restart it many times until you either see a white screen or are confident the issue isn't happening. If the latter, now change the program to start one of the pumps and do the repeating test, see if it occurs.


I can run it without the 24volts energized. But I have a simulator built that has everything but the pumps and it has never given me a white screen.

Is the 5V a totally separate supply, or is it running from a regulator off the 24V source?
I have 2 different industrial power supplies from PULS one is 24vdc and the other is 5vdc.

Also, I'm curious if this white screen is happening because the Arduino is resetting, or if it's happening in the middle of program execution. If you have a spare pin on the Arduino, could you set up an LED that's enabled at the very start of the sketch, and then gets turned off once the main loop is underway? That might help diagnose if it's a full glitch/restart or something else.


Negative. When the white screen happens the pumps keep running. I can even push the abort or mode buttons on the screen even though I can not see them and they respond appropriately. . Also there is a separate safety relay that energizes the relay card during setup as the relay card is active low.
So I think it is something else.


Finally...if the second test program described above (run screen and one pump) runs without incident, but the full program has this issue sometimes, I'd start to suspect the program is running out of RAM.


Well only one pump runs at any given time, but I could do something of this nature, however the mid cycle whiteout has me scratching my head.
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Re: 2.8 inch tft shield white screen

by urthlight on Thu Apr 04, 2013 1:08 pm

So how would one tell if he were running out of RAM?
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Re: 2.8 inch tft shield white screen

by urthlight on Thu Apr 11, 2013 11:27 am

New chapter:
So I ran it for about 8 hours with the safety relay open so the 24vDC could not make it to the motors but the power supply was still running. No white screen. So I moded the program so it would loop continuously. It then ran all day, and all night. On arrival the next morning there was a white screen. So I refined the 24vDC ground.I found that the 5VDC was not grounded. So I bonded them together and started having comm errors with the host PC and a Arduino reset on occasion.
So I let the 5VDC float again. Ran it all day yesterday no problems. Left it running again last night and white screen on arrival this morning. I am now sequentially running each item for 500 mSec waiting for white screen. None so far. The program I am running for the test is pretty much the same as the final version I just removed the case statement and put in a routine to exercise the motors. So I have pretty much ruled out EMF. My program is not so big only 36,704 Bytes OF 258,048 Used. Any Ideas? This project is done except for the white screen.
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Re: 2.8 inch tft shield white screen

by pburgess on Thu Apr 11, 2013 1:05 pm

Have we tried using an older version of the library? A similar white-screen issue was sometimes seen with particular boards and some possibly over-aggressively optimized stuff in recent versions of the code. Try it with this version:

https://github.com/adafruit/TFTLCD-Libr ... 5263787d1f
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Re: 2.8 inch tft shield white screen

by urthlight on Fri Apr 12, 2013 10:45 am

Well it ran all night with the 24VDC removed via the safety relay and no white screen. So I shut her down to do a couple of things and on power up I got a white screen. Doing more testing. So I still cannot rule out the display which is inhibiting me from releasing it to the customer for beta testing and acceptance, preventing me from buying screens and parts for production.
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