slippyr4 wrote:
> 2010/1/20 Ruben J=F6nsson <ruben@pp.sbbs.se>
> =

>> Make sure that you don't have any interrupts that interfere with the LCD
>> writing. Especially if the interrupt uses bits in the same port that is
>> used by
>> the LCD. Also make sure that you don't have any read modify write (RMW)
>> problems.
>>
>>
> Maybe there's a problem here.
> =

> I use RB5, RB6, RB7 for E, RW, RS.
> =

> I'm using some of the lower bits in port B for other things.
> =

> All of my reads and writes to port B are in the form:-
> =

> PORTBbits.RB2 =3D 1;
> =

> I'm not sure if the compiler generates "safe" code for that, or not.
> =

> I guess in a future hardware revision I should change ports that i'm usin=
g,
> so I can get the LCD on it's own unique port. I think i'll need to change=
 to
> a 40 pin part to do that though, i'm running out of capacity on the 28 pin
> parts.

At 20 MHz you might have to add one or two NOP's between each
direct bit-instruction on a PORT reg. That should nornmaly be enough
if there isn't some un-normal capacitive load on the pins.

And, what do you do with RW ? Do you ever *read* from the LCD ?
If not, just tie it low and save a pin...


-- =

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