Matrix Orbital Corp

Hi guys,

I've gotten a problem with a VK202-25 display I purchased last november. It worked fine until now, but now it does not respond correctly to data on the serial port. Also I never changed the startup-screen, but it has changed to the garbage you can see in the attached image (sorry about the less-than-sharp picture, but it should give you an idea).

Whenever I try to send a text string, or a command, various strange characters begin to roll over both lines of the display, and it only stops when I turn off the display. I've now removed it from the setup, and connected it to a pc with a serial cable and +5V/Gnd only. Same problem.

This is me guessing: It seems like the vfd itself works correctly, but that the atmega on the interface board is somehow broken. Is it possible that the firmware has been messed up, somehow? If so, is it possible to reset or reupload the firmware?

//michael

Hi Michael,

I'm sorry to hear you're having trouble with some pretty random characters showing up on your screen.

First off, it seems like your start up screen has somehow been changed, which explains the characters showing up when power is applied.

Second, I suspect your baud rate may have inadvertently been changed, resulting in some rather abnormal behavior. Try the manual override procedure outlined in your manual to set it back to 19200. You can also check out the guide for this procedure in the forums here.

Let me know if this improves communication, and those crazy characters.

Thanks,
Troy

Clark wrote:Second, I suspect your baud rate may have inadvertently been changed, resulting in some rather abnormal behavior. Try the manual override procedure outlined in your manual to set it back to 19200. You can also check out the guide for this procedure in the forums here.

Gee, you're good! Reading the manual would have been a good start. However I thought it would reset the baud rate using the following procedure:

1. mount jumper
2. turn on display
3. turn off display
4. remove jumper

but I had to leave the jumper on, and go through the procedure in the post you linked to. Actually now that I know how to do it that might even be what is written in the manual under step 5

Now it seems like it remembers the baud rate, and all I have to do is change the startup screen.

Thanks again,
Michael

Hi Michael,

No worries, I'm glad you've got your communication troubles figured out. The manual override does return the defaults to the display, however, it does not save them. This is why you've got to save the settings for them to stick.

For the startup screen, I'd suggest checking out boot edit or the older boot logo. They make uploading a little quicker, and let you throw in some custom characters rather easily.

Best of luck with your display, if you run into any more trouble down the road, we'll be happy to help you out of it.

Thanks,
Troy