Frame Ground on CFAG320240C-FMI-T

[Radical Ans]

What is this pin used for? Is it the ground for the +25V powering the LCD or is it for some other purpose?

David Panseri

Crystalfontz LCD Blog

Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.

 

[CF Tech]

The frame ground is typically a trace that connects to the metal bezel and mounting holes. It might help in some interference situations or be used to help a bit with static protedtion (EMI/ESD).

In many applications it is left open.

 

[Radical Ans]

Thanks for the info. I have another question about the same LCD. Do you have any sample code on how to write data to the LCD? I'm trying to do it based off of the controller datasheet but right now I'm having no luck.

Thanks,
David Panseri

 

[CF Tech]

Please check your private messages.

 

[Radical Ans]

One more quick question. I wrote some code based off of what you gave me and whenever I run it the screen just flickers violently and the image that is suposed to appear doesn't. You can check out the code here. I don't know if there is something wrong w/ the LCD itself or if I'm just initalizing it wrong or what.

Thanks,
Dave Panseri

 

[CF Tech]

Without doing a line-by line compare, I do not see any obvious problems.

Usually this type of thing is due to a wiring or programming mistake.

Make a test program that sets all the lines low except for one, and make that one toggle slowly (like 1 sec on and 1 sec off). Then use your voltmeter or 'scope to confirm the correct line is toggling at the LCD's connector.

Repeat this process for each data and control line.

Once you are 100% sure every line is operating correctly and independently, if the LCD still does not come on, then there is probably a porting error or timing error.

 

[Radical Ans]

lol I just realized i was setting the RW line high instead of low, thus reading rather than writing. I got it to display an image but It's really faded. I think this may be becuse i'm powering it of 3.3V rather than 5v. I'm going to try powering it off 5V tomorow and see how that goes.

 

[CF Tech]

Did you try adjusting the white pot on the back?

 

[Radical Ans]

yeah it just stays faded and either gets clear or kinda shakey.

 

[CF Tech]

I guess you might try +5v then. Is that display rated for 3.3v?

 

[Radical Ans]

I think it's 5V but I only had a 3.3V header on the board I'm using.

 

[CF Tech]

Radical Ans wrote: I'm going to try powering it off 5V tomorow and see how that goes.

Let us know how that works out.