Come to think of it maybe the 555 idea is more 'within specs' of the LCD
module. Where can I get an example of this configuration, the data sheets
don't appear to include it.

TIA

Wesley Moore

On Wed, 22 Sep 1999, Michael Rigby-Jones wrote:

> > I've got two completely unrelated questions for you all:
> >
> > 1. What is the corelation between HEX file size and the program mem usage
> > on the PIC? Is it file size / 2 like I suspect? Can you get the compliler
> > to spit out stats like those shown at the end of Microchip's source code
> > in their application notes?
> >
> No, it's not size/2 because although each byte is represented by as ascii
> hex, i.e. 2 characters, this dosen't take into account the header strings
> and the checksum.  I've sent you a hex to bin utility off-list which will
> convert an intel hex file into absolute binary.  Because the size of the
> PICs word is 12 to 16 bits, two bytes per word are used so if you divide the
> resulting binary filesize by two, you will get the correct result.
> Note that if config bytes are included in the hex file then it will be
> slightly too large...not sure of the exact figure though.
>
>
> > 2. I have a Seiko L2432 2 x 24 char LCD module, which I am having some
> > difficulty getting a decent contrast out of. I am using what appears to be
> > a fairly standard usage of a 10k trimpot to control the LCD drive voltage
> > (pin 3) however the best contrast occurs when this is fully turned towards
> > the ground side. When I connected ground straight to the pin the display
> > was slightly darker but still not upto what I would consider to be a
> > reasonable standard. Anyone have any ideas?
> >
> > Wesley Moore
> >
> Some displays (mostly extended temperature types) need a negative voltage on
> the contrast pin.  Check the specs of your display to see what the minimum
> voltage allowable on the pin is.  You can generate a negative voltage from a
> simple charge pump driven from e.g. a 555 timer or use one of the special
> purpose -ve voltage generators.
>
> Mike Rigby-Jones
>