Problem with 4x20 LCD & BS2.

Wolverine69 · 2009-01-19 02:17

(I posted this several hours ago, but it's never shown up.· So I'm doing it again)

This past week I received my new Parallax 4x20 LCD and promptly hooked it up to my BS2 & BOE.· The problem that I'm having is that there are what I call 'ghost' characters on the display below the characters that I actually want displayed on the display.

Yes, I have tried adjusting the contrast control on the back of the LCD PCB and it doesn't help.

Any ideas?· Do I have a bad LCD?

ETA: Upon further examination of my LCD I've noticed that the pixels that make up each character are not all the same darkness.· Many of the characters appear to have been partially 'erased'.

' {$STAMP BS2}
' {$PBASIC 2.5}
TxPin CON 0
Baud19200 CON 32
HIGH TxPin
SEROUT TxPin, Baud19200, [noparse][[/noparse]12]   'Form Feed - used to clear the screen
PAUSE 100   'pause for 1/10 second
SEROUT TxPin, baud19200, [noparse][[/noparse]17]   'Turns on backlight
SEROUT Txpin, Baud19200, [noparse][[/noparse]"Hi"]

Post Edited (Wolverine69) : 1/19/2009 3:06:27 AM GMT

sylvie369 · 2009-01-19 15:48

First step: turn it on in test mode. You set both DIP switches on the back to OFF, then supply 5v and ground AND NO OTHER CONNECTIONS. You should get the standard Parallax startup test characters. If you still have the problem you're describing, I'd say you have a bad LCD. If not, then there's probably something about your wiring or possibly programming.

Problem with 4x20 LCD & BS2.

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