8-bit Microcontrollers中的主题 Re: LCD on HC08AP

LCD on HC08AP

HC08AP — Mon, 27 Mar 2006 18:04:27 GMT

I have an In-Dart for HC08AP and a demo board for HC08AP64.

My problem is to communicate with an LCD ( driver HD44780 ) from my demo board.

Have you ever been resolved this problem ?

Thanks

Marcolino

Re: LCD on HC08AP

alex_spotw — Mon, 27 Mar 2006 22:56:42 GMT

Hi Marcolino:

You have to give us more information than that, to be able to help you.:

1. What is the actual communication problem?
2. How is your LCD module connected to the demo board?
3. Which language are you using (assembly, C)?

There are several things to look when using LCD displays
1. Reset sequence,
2. 8-bit interface vs 4-bit
3. Contrast Level (you will amaze with how many people have a perfectly working LCD and Software, but fail to put the correct contrast level to see the characters).
4. Delays to write information into the LCD controller,

Let us know!

Regards,
Alex

Re: LCD on HC08AP

rocco — Tue, 28 Mar 2006 05:52:06 GMT

alex_spotw wrote:

3. Contrast Level (you will amaze with how many people have a perfectly working LCD and Software, but fail to put the correct contrast level to see the characters).

I wouldn't be surprised.
I've been there. I spent a whole day there.
Boy, did I feel dumb (besides my usual looking dumb).

My contrast adjustment had to be all the way over at the bottom end of the scale for anything to show up at all. At 0% to 5%, you could see characters. At 5% through to 100%, you just saw a blank screen.

Also, are you monitoring the busy bit? or just using delay loops?

And don't be afraid to exaggerate the delay times during initialization. It might bother you, but it won't bother the LCD.

Re: LCD on HC08AP

bigmac — Tue, 28 Mar 2006 11:17:23 GMT

Hello Marcolino,

Have a look at Application Note AN2940, "LCD Driver for the HC08/HCS08 Family", and the associated software file. It covers both 4-bit and 8-bit interface modes for LCD displays based on the HD44780 device.

Regards,
Mac