Need help with CFAH2002A-NGG-JP

[Euticus]

I am using the CFAH2002A-NGG-JP with the melabs LABXUSB dev. board. I know the hardware is OK, because I loaded a demo hex file and the display works. I am programming in c using the microchip mcc18 compiler and the lcd library. the target chip is an 18F4455 running at 20MHz. The library function doesn't work, so I wrote my own functions. The display seems to init correctly (it clears), but I cannot seem to write any characters to it. This ought to be the simplest part! Thisis driving me nuts! Do you have any example c code or an algorithm. The datasheet I have only shows the init flowchart. I must be missing something.

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[CF Tech]

What voltage are you supplying to pin 3 (Vo)?

 

[Euticus]

Not sure. It is permanently set on the board. I know it is not a problem with contrast, because I have a hex file that will display a "Hello world" message correctly. i know my code inits because what was one row of completely black squares becomes two rows of light gray squares (I assume these are blanks, and the contrast is a little too hi-or would that be too low?)

 

[Euticus]

The schematic shows the Vo pin connected to ground through a 270 ohm resistor.

 

[CF Tech]

If one set of firmware works, then I guess that means the hardware must be working OK.

You might try a different library, I am sure there are tons of PIC LCD libraries out there:

http://www.google.com/search?q=PIC+HD44780+LCD+source

There should be some good information on http://www.piclist.org

I have some 4-bit sample code here you can look at:

http://www.crystalfontz.com/backlight/PIC_4-bit_LCD_sample_code.zip

It is pretty old though, I am not sure it would be useful on a modern PIC.