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How to clear the LCD RAM on Rayman's PSB? — Parallax Forums

How to clear the LCD RAM on Rayman's PSB?

MicrocontrolledMicrocontrolled Posts: 2,461
edited 2010-08-17 08:54 in Propeller 1
I have designed an OS for Rayman's PSB that uses a semi-GUI interface to launch new applications in from an SD card. The problem is that there is almost always a display error, sometimes the Propeller and screen crash for no reason. I am guessing because in each new app the settings for the LCD are changed without rebooting the LCD.
If I remember correctly, the LCD has onboard RAM (QRAM?) that stores the screen and settings. Is there a way to clear this, or just reset the LCD, from software only?

Thanks,
Micro

Comments

  • RaymanRayman Posts: 14,889
    edited 2010-08-14 20:54
    Hmm... I don't think the 4.3" display has any memory at all... It's very similar to a simple vga monitor. I'm trying to remember if there is a reset pin on it or not, maybe that would help....
  • wjsteelewjsteele Posts: 697
    edited 2010-08-15 02:40
    Rayman wrote: »
    I don't think the 4.3" display has any memory at all... It's very similar to a simple vga monitor.

    That's correct, there is no memory at all on the 4.3" display. The smaller PSM's LCD has memory, however.

    If you're seeing screen corruption, the first place I'd look is to see if you're overwriting part of your memory, specifically any variables around your screen buffer. I'm positive, based on your symptoms, that you are.

    If you overwrite the memory, you'll normally only get character corruptions (random characters appearing to the left or right of the screen in most cases.) In most cases, it'll be harmless, but sometimes the corruption is so bad that you'll actually end up writing over some important memory positions, which will cause the system to lockup or shutdown unexpectedly.

    Bill
  • RaymanRayman Posts: 14,889
    edited 2010-08-17 06:09
    Any luck with your problem? Bill is right about memory issues being a potential problem. I suppose the other thing that could be going wrong is pin contention issues...
  • HarleyHarley Posts: 997
    edited 2010-08-17 08:54
    Doesn't gr.clear clear the screen?

    If not maybe the screen/tiles/etc. aren't defined properly.

    Look at Rayman's demos for how it is handled. I used his Paint! demo as a place to start my program using the 3.5" LCDs. I'm pleased with the results; both the LCD module and the Spin code.
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