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Question about LCDs on CoreLPC17 - did I blow my VFD?


borfo
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Hi...  I'm in the process of building a SEQ V4.  Core LPC17 is assembled, V4 firmware is installed.  I have some Noritake CU40025-UW6J VFD Displays that I'm planning on using with the V4.

datasheet: http://media.digikey.com/pdf/Data%20Sheets/Noritake%20PDFs/CU40025-UW6J.pdf (pinout is on page 18)

product page: http://noritake-vfd.com/cu40025-uw6j.aspx

 

 

The VFD pinouts are identical to standard 40x2 LCDs, except they're missing pins 15 and 16 (lcd backlight).  I made cables, checked the pinouts on J15, and hooked one of the VFDs up to J15A.  Booted up the Core, and the VFD worked fine - showed the "searching for SD card" message, etc.

 

So I wired up a second VFD and connected it to J15B.  This time, the second VFD (on J15B) worked, but the first one (on J15A - the one that worked fine a second ago) didn't.  I didn't change anything about the connection on the J15A VFD.

 

I thought maybe there wasn't enough voltage to drive both or something, so I disconnected J15B and booted again.  The J15A VFD still did not work.  It doesn't work when plugged into J15B either.  I don't have anything else to test it on right now, but I suspect I've fried the VFD somehow.

 

The second VFD, originally plugged into J15B works fine, whether plugged into J15A or J15B.

 

Is it possible that voltage might have been sent to a data pin on J15A when both VFDs were plugged in?  I've got an extra VFD, so all is not lost, but I'd rather not fry it too if there's something wrong with my wiring...

 

Pin 3 on the VFD is "No Connection", and on J15 that pin is VU - I assumed there would be no harm in leaving that connected, but maybe I should have cut that wire?

 

There are no problems with the cables, by the way - I checked them for continuity, and checked for continuity leaks on adjacent pins...

 

Any comments are greatly appreciated.

Edited by borfo
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