Interfacing to GLCD -are FGND and VEE the same thing?

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jmur

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Im using a cheap GLCD with a KS0108 controller that I bought of ebay the only bit of information I could find on the GLCD is the image below.

The block diagram shows VEE but theres no VEE shown in the PIN assignment only FGND, would I be right in assuming that FGND and VEE are the same thing.

**broken link removed**
 
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VEE is the LCD drive voltage that is shown as Vlc on your diagram.

Edit, think I'm wrong. It looks like you need a seperate -8V supply to drive it.
Edit2, try powering it up and see if you find a negative voltage on any pins.

Mike.
 
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This is a little bit confusing then -why is both VEE and VLC shown in the diagram if they are both the same?

edit: I try powering it up now...
 
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Vlc jumps around a bit 1v - 5v and fgnd is at -50mv

edit: (vlc) slowly increases and then decreases but not necessarily all the way to 5V, really very hard to characterize..
 
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hmm looks like the glcd fooled my DMM, I checked the voltages with my DSO and and found 5.5v at VLC and -3.6V at FGND
 
ericgibbs said:
hi,
Look at this link.
KS0108 Controller
Click to expand...


Thanks, I had a look at that page before but I wasn't sure if the VEE and FGND were the same thing at the time.

So should I follow the connection directions from that site (quoted below) or from the diagram in my first post

By connecting a 20k POT between Vee (Pin 18) and 5+v Vdd (Pin 2) with the pots wiper connected to Vo (Pin 3) one is able to adjust the LCD’s contrast.
Click to expand...
 
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It looks like your FGND is Vee.

I just plugged my GLCD into a dev board and I get -4V on Vee (pin 18). This -4V is connected to one end of a pot, the other end is ground and the wiper goes to Vlc. For connection details see **broken link removed**.

I might even rewrite my GLCD code now I have it connected.

Mike.
 


Thanks, unfortunately I think I fried my GLCD last night, I foolishly connected the power and contrast adjust in reverse -somehow mistaking pin 1 for 20.. now there is 5v on pin18 and the only thing that works is the backlight.
 
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