LCD broken?

Brietech

Senior Member
Hmm, so I purchased one of these 24x8 character LCD's off of ebay (http://cgi.ebay.com/NEW-SERIAL-24-x-8-LCD-WITH-CONTROLLER_W0QQitemZ120093993964QQihZ002QQcategoryZ50915QQrdZ1QQssPageNameZWD1VQQcmdZViewItem)

Whenever I power it on, though, all of the blocks turn on and come up solid, and I can't get any response from the serial port. Is it probably broken? I think I accidentally reversed the polarity when I was initially wiring it, but that usually doesn't kill electronics completely. I've just never had that happen with an lcd display before...hmm.
 

womai

Senior Member
You may want to play with the contrast setting (the pin hooked up to a 10 kOhm trimmer in the standard schematic for LCDs. Since you get all blocks that probably means the display is OK but the contrast is set too high. Some LCD displays are extremely sensitive to the voltage on the contrast input - slightly too much and it's all black blocks, slightly too little and the display is blank. I had similar issues when I first played with a parallel LCD.

Wolfgang
 

Brietech

Senior Member
It has a "contrast slider" that's just a linear pot, and it slides pretty smoothly from "barely visible" to "solid navy", so I'm thinking that that is not it. At least, fiddling with it made no apparent difference (just increasingly faded solid blocks)
 

hippy

Technical Support
Staff member
If you did inadvertently reverse power it is possible that the serial decoder has been damaged but the LCD itself has not. That could explain why the LCD is not being initialised and is displaying black blobs.

In my experience though, a reset but uninitialised LCD will show just one line of black blobs or just alternate lines of black blobs with the those interleaved blank. That may not always be the case with all controllers.

Perhaps the module needs external initialisation, an initial command ? Check the voltage required for its serial and the baud rate and you can try with Txxxx and Nxxx baud rates.
 

Brietech

Senior Member
Thank you all, I got it working! For some reason it won't work when hooked up to hyperterm . . . Not really sure why! I used the terminal in the Programming Editor though, and it worked perfectly. Horray!
 
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