LCD problems with adjacent HIGH

Archiver

Hi,

I've a project which has uses parallel LCD module
controlled with BS2P24 with LCDOUT and LCDCMD with
basepin as 9 and INPUTS on 3 & 4 (the whole code is
long so won't post it at this stage). This all works
fine (apparently...). Anyhow, I wanted to control
backlight in software and am driving from PIN 8 with
usual resitor/NPN/limiter resistor setup.

I grafted code into the working program and found that
HIGH 8 switches light on fine. However the light goes
off as soon as either LCDCMD or LCDOUT steps passed in
program. I haven't had time to dissect this out with
minimal programs, or by moving back to the breadboard
to check behaviour, but wondered if anyone had been
here before.

I'm particulary intrigued that online manual says that
LCDOUT can use basepin as 8 or 9 with the same other
driving lines and began to wonder if PIN 8 was a bad
choice (it happened to be convenient on the board).

Adrian


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Archiver

Hello, an update,

> I've a project which has uses parallel LCD module
> controlled with BS2P24 with LCDOUT and LCDCMD with
> basepin as 9 and INPUTS on 3 & 4 (the whole code is
With a msall program:

HIGH 8
PAUSE 300
LCDOUT 9,...

I've established that LCDOUT on 9 does drop pin 8 too. LCDOUT on 0 or
1 doesn't. LCDCMD is OK too.

I've moved the control line from pin 8 to pin 0 and it works fine. I
suppose I'm now concerned whether:
1. I've misunderstood LCDOUT documentation
2. My STAMP is odd
3. There's a slight glitch in LCDOUT.

Maybe someone else could chck - it doesn't need an LCD to do it!

TIA

Adrian