> First time using an LCD (Jameco/Ampire 2x16 unit), and just
> experimenting a bit for now.  If you're curious, datasheet
> is at: https://www.jameco.com/Jameco/Products/ProdDS/171715.pdf
>=20
> I'm controlling the LCD manually (for now) with 11 DIP switches.
> Sounds painful I know, but it's not that bad... if it works.
> Which it doesn't exactly.
>=20
> For each bit-combo. I setup the bits with enable set LOW, then
> toggle enable to HIGH and back to LOW.  First I ran though the
> initialization sequence this way, then set DDRAM to address 0,
> then wrote data LLHHLLHH to the RAM.  What I get is the char
> '3' display, but on the first 6 character positions.  If I
> toggle the enable to HIGH and back to LOW again, it writes '3'
> in the next 6 or so positions.
>=20
> That's odd.  Anyone know why?  My guess is that I'm missing
> something fundamental on the operation of LCD's, and the
> datasheet is not exactly as well detailed as, say, a Microchip
> datasheet.

You have to use a debounced signal to the enable input. The LCD=20
writes one character and advances to the next position with=20
every high to low transition on the enable input. Since the=20
input isn't debounced you get several high to low transitions=20
for every toggle of the switch.

>=20
> Another Q... I guess CG stands for character generator, but
> why is there an operation to write to CG RAM?  What's the
> purpose of that?  Can I create my own fonts or something?

Character number 0-7 (mirrored in 8-15) are mapped to CGRAM=20
(character generator RAM) instead of the internal ROM character=20
table. One character needs 8 bytes in the CGRAM to represent=20
it's image on the display. Character 0 uses address 0-7 in=20
CGRAM, character 1 uses address 8-15 and so on. The First byte=20
is the top row and only the five lowest bits in every byte are=20
used.

This means that you can only show 8 different user defined=20
characters on the display simultaneously.

You write to the CGRAM just as you write to the DDRAM, You just=20
have to send the 'set CGRAM address' command to the display=20
first. You do this once, then the LCD controller advances the=20
address for every byte you write to it. When you are done,=20
writing to the CGRAM you have to reset the address pointer to=20
DDRAM with the 'set DDRAM address' command or 'Cursor home' or=20
'Clear display'.

Hope this helps,=20

Ruben

>=20
> Thanks,
> -Neil.
>=20
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

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