GLK12232-25-SM: text display broken

a.brooks · Post by **a.brooks** » Sun Sep 02, 2007 10:50 pm

Hi,

We have a number of "GLK12232-25-SM"s. They have all been working for a period of a couple of years, except for two which have broken. These particular two had been working correctly for quite some time.

The symptoms for the two are identical:
- I can communicate via serial with them (I verified that they report the correct module number),
- I can clear the display,
- I can not display any text (the command simply has no effect).

After the first one failed I simply chalked it up to something weird, and replaced it with a new one.
However with this second one with identical symptoms I thought maybe you guys could shed some light on what might be happening?

Thanks,

Alex

Clark · Post by **Clark** » Tue Sep 04, 2007 4:59 pm

Hi Alex,

Thanks for your question. When a GLK does not display text that is sent to it, it may be because it is lacking a font. I would recommend using the MOGD# program to upload a font to the unit and attempting to write to it again.

Hopefully this will produce some results from your display,

Troy

a.brooks · Post by **a.brooks** » Tue Sep 04, 2007 5:07 pm

Hi Troy,

Thanks for the response. This seems really unlikely though -- The unit has been sitting in situ for a long time, all I have ever done with it is display text (ie no mucking about with the fonts). Is it possible for the fonts to have removed themselves? Has this ever happened before?

Alex

Clark · Post by **Clark** » Wed Sep 05, 2007 12:17 pm

Hi Alex,

I would have to say that I have never heard of a display erasing a font, however, I have not been here very long. Nonetheless, I would like you to try to upload a font to the display and ensure that it is selected within MOGD# using the 'Current Font' option to confirm that a font is in fact loaded. This will let me know if the unit is indeed defective and allow me to issue an RMA for its repair, or that it was just missing a font and everything is hunkie dorie now.

Thanks for your continued patience in this matter,

Troy

a.brooks · Post by **a.brooks** » Mon Sep 10, 2007 1:32 am

Hi Troy,

I downloaded and installed the MOGD# software. Before uploading a font, I thought I'd just try displaying some text. This worked, and revived the LCD unit. I then tried again with my driver, and everything works now.

So it would appear that the LCD somehow got into a weird state, and the MOGD# driver is prodding it slightly differently from my driver.

As to how it got into this state, my guess is a flipped bit. At 19200 baud, when running for weeks on end, there will be a reasonable number of bits flipped. Since we have several LCD units running for several months (with no checksums in the protocol), I guess anything could happen.

Do you have any idea what state the unit may have gotten into, or what MOGD# might have done to get it out of this state?

Thanks,

Alex

Clark · Post by **Clark** » Mon Sep 10, 2007 1:44 pm

Hi Alex,

Glad to hear that your board has been miraculously revived by MOGD#. The only situation I can think of that may have triggered this chain of events is a change in your current font settings. If your current font had been changed to a location where no font was stored you would not be able to write to your display. Using MOGD# the current font is set by default to location 1, where a font could very well have been stored, allowing you to write once again to your display.

Hopefully this will shed some light on the apparent all healing nature of MOGD#,

Troy