On Fri, 21 Apr 2000, Eisermann, Phil [Ridg/CO] wrote:

> > RS=Low
> > R/W=High
> > E=Low -> High
> > Read Bit-7

8<snip...

> yes, that's how I'm doing it. except E toggles low->high->low.
> and with a 4-bit interface, you're supposed to do it twice.

Ditto.  I tried doing it once, and doing it twice - either way it didin't
work.  Since I don't have an ICE and didn't have the time to set up the
scope to see exactly what was going on, I don't know exactly what was
happening, only that the wait_busy routine wasn't working.

> That's the way it is supposed to work in theory. In
> practice, you need to change the data lines from
> input to output in order to read the data. And as
> soon as you do, the LCD (at least mine, and
> apparantly Dale's as well) goes south.

I was setting TRIS to 00001111 (LCD data pins input) before toggling any
of the RS, RW or E lines.  In theory, this shouldn't affect the LCD - in
fact, I share pins <> E between the LCD and a DS1620 temp. sensor, so I
know the LCD can tolerate data pins being TRISed and used for other things
when it's not enabled.

> Perhaps my LCD is half-dead/ESD impaired?

I doubt it.  I'm starting to wonder about the hardware now, though...
unfortunately it will be at least a day before I can go retrieve the board
and scope to play with it, I left it at work.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
                -- Isaac Asimov