[Noisebridge-discuss] First e-mail, and an LCD question

[Michael Frederickson]

I want to thank everyone for their responses to my first e-mail!  I'm
excited to get started with this community.  I think I'll be swinging by
next week.

Thanks all,
Mike

On Tue, Jun 2, 2009 at 9:59 AM, d p chang <pchang at macrovision.com> wrote:

> Michael Frederickson <michael.frederickson at gmail.com> writes:
>
> > Specifically, my current project includes trying to get some info
> > displaying on an HD44780 LCD with a PIC16F690 microcontroller, using
> > some code I'm trying to compile with HI-TECH's compiler.
> > I'm having a bit of trouble, and think it's probably in my
> > timing.
>
> i think you'd have a hard time signalling faster than the minimum
> setup/hold times on the lines w/ a pic. eg, in pseudocode a write could
> look like
>
>      rs   = <whatever>
>      rw   = 0
>  <setup>
>      en   = 1
>      data = <whatever>
>  <setup>
>      en   = 0
>  <hold>
>      rs   = Z
>      rw   = Z
>      data = Z
>
> w/o checking for exact #s, setup/hold are in the tens of ns range (at
> least < 100ns). any delay here would be enough to meet the timing
> constraints easily (given something like the 8mhz internal clock).
>
> thinking about this a little more, you can't release/toggle en too
> soon/fast (on the order of a few cycles should be enoug), but i don't
> think that the lcd refreshes that fast either :-)
>
> \p
> ---
> Birds are entangled by their feet and men by their tongues.
>                - Thomas Fuller
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