fpga4fun.com

Hi

I am trying to use the LCD screen that is part of my Spartan-3an starter kit. I'm using VHDL (so the LCD project on fpga4fun doesn't help very much) and I specifically don't want to use the PicoBlaze or MicroBlaze processors provided in other documentation.

The Spartan-3an documentation [url=http://www.xilinx.com/support/documentation/boards_and_kits/ug334.pdf]here[/url] provides an initilisation process for using a 4-bit interface but I'd like to use the 8-bit interface.

First question: Do I have to go through a similar initialisation to use the 8-bit interface and what is it?

I forged ahead and used an initilisation algorithm I found [url=http://www.xilinx.com/products/boards/s3astarter/files/s3ask_dna_reader.pdf]here[/url] but when cleared the display, turned it on and returned the cursor (using the LCD commands and in that order) all I get is a clear screen with no flashing cursor. If I then try to write a character to the screen nothing appears. When I view my application in a simulation the initilisation commands I send to the LCD and the commands to write a character to the screen are all sent to the LCD correctly. I am aware of the 40us required between most commands too.

After 4 days of trying to figure out what is going on and why my execution doesn't match my simulation I'd appreciate any help anyone has to offer. If you are feeling brave I can provide my VHDL files via email.

Someone knowledgeable pointed out that I should try to use the 4-bit interface since I had the confirmed init sequence and needless to say it worked so I have discarded the idea of using the 8-bit interface. If anyone does know how to implement the 8-bit interface though could he/she post it as I'd be interested to see where my mistake was and it may help others.