LCD Display still active in Standby?!

[Bobby]

Hello,

I have the big problem that my LCD Display is still active when the computer is in standby, which means the LCD Display shows the last information it got and the Backlight is on.
I tried plugging the LCD Display to a self-powered USB Hub at a Master-Slave socket and disrupt the +5V USB-Pin of the Cable going from the USB Hub to the Computer, but then Windows won't recognize the USB Hub and therefore the LCD Display neither.

Can anybody help?

[limbo]

Try to use shutdown message. Using spaces there will cause the screen to be cleared.
In order to close the backlight your LCD module must support this function.
What typo of LCD back-plate are you using? Refer to its manual, if any, for more info about it.

[limbo]

Try to use shutdown message. Using spaces there will cause the screen to be cleared.
In order to close the backlight your LCD module must support this function.
What typo of LCD back-plate are you using? Refer to its manual, if any, for more info about it.

[Bobby]

Hi limbo,

thanks for your fast answer
I have this 20x4 LCD Display: ebay[dot]com/itm/20X4-LCD-Smartie-Kit-Starter-White-Blue-LCD-/160871015452#shpCntId

I just tried your hint, but unfortunately it doesn't work.
The Problem is, that when the computer goes in standby, the first, second and third line of the LCD Display are cleared. But the last line freezes to the last information which was displayed there.

The backlight remains on.


But I have recognized a very odd behavior: When I plug the LCD Display per USB to my computer, only the first time I go into standby the Display is completely cleared!
But after awaking the computer and then again going into standby, the last line freezes and the backlight stays on.

[Bobby]

Okay I think i know what the problem is:
I'm using not the matrix.dll, but dperrows LCDT.dll because I had the backlight issue after awaking from standby (backlight off & couldn't be turned on) from here: forums.lcdsmartie.org/viewtopic.php?f=8&t=3279&p=18755&hilit=backlight#p18755

With the matrix.dll, I don't have the problem with the backlight remaining on or the last line freezing, but the backlight is off & un-controllable after waking up.
With the LCDT.dll, I have the problem with the backlight remaining on and the last light freezing, but not the Problem with the backlight off after standby.

[dperrow]

Hi Bobby,
I've been looking at this today but not found any issues. I've modified the code to output lots of spaces when the power goes off and i'll send this separately.

One thing I did find though, on my laptop, was that my display would come back on shortly after power off because the BIOS and windows were set to keep the USB power on when on standby. There was a setting in the bios to switch this off - might be worth a look.

Dave

[dperrow]

Hi,
Thanks to help from Bobby I've managed to fix the bug with suspend resume where the display sometimes would not clear on shutdown and will display random characters or the last thing displayed and sometimes leave the backlight on. I suspect this is the original issue with the matrix orbital dll but don't have a development environment which would allow me to try the fix in that. If anyone has, please feel free to try it. The problem is that the dll closes the communications before the USB driver has completed the transfer so random characters end up on the display. I suspect this is peculiar to specific USB to Serial drivers but don't know which. Anyway the solution is to include a delay (I put 1 second) after the last character is sent but before closing the device. I've updated the dll and attached it in the original forum (this one doesn't support attachments) at:

http://forums.lcdsmartie.org/viewtopic. ... 417#p19417

Cheers
Dave