Bob McIlvaine wrote:
> I have an LCD display with the Hitachi chip set hooked up in 4 bit mode.
> Works fine.
>
> But, when the processor resets and resend the software start-up sequence to
> the LCD, the LCD goes south.

That's a problem I also had when trying to access the LCD in 4 bit mode.
The point is that there is no way to distinguish between the two 4 bit
cycles of the LCD. When your circuit goes into reset, the lcd-enable may
go high and voil` - you are now in the second cycle of an uncomplete 4
bit access (but after reset, you can not be sure that you are in the
second cycle!).
The solution of this problem is (as I remember it) to switch the LCD to
8 bit mode at startup - and send this command twice (or three times - I
don't have a datasheet nor access to my old source codes at the moment)
as you would do if you had 8 datalines. So you send two (or more...)
nibbles, both with "switch to 8 bit mode", ignoring in which 4 bit cycle
you are. After that the LCD is in 8 bit mode regardeless in which mode
it was or in which 4bit cycle.
Now switch it back to 4 bit and proceed with startup...

This is how it worked for me
Florian