piclist 2000\06\05\184335a >
Thread: How to control a dumb LCD
picon face BY : Bob Ammerman email (remove spam text)

LCD's require an AC waveform. There is no reason that the PIC cannot
directly generate this waveform. Just tie one PIC output pin the common, and
other pins to the segments. You toggle the common pin periodically, and each
time you do so you also toggle all the segment pins (try COMF PORTx,F for
example to do 8 at a time).

To turn a segment on you just make sure that it is toggled 180 degrees out
of phase with the common. To turn it off you toggle it in phase with the

Alternately, you can run each segment line thru an external XOR gate, the
other input of which is connected to an oscillator. This is much simpler
from a code standpoint, but requires more hardware.

Bob Ammerman
RAm Systems
(high function, high performance, low-level software)

{Original Message removed}
<020b01bfcf3f$6370f660$269b9cd1@ramdell> 7bit

See also: www.piclist.com/techref/io/lcd/pic.htm?key=lcd
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Subject (change) How to control a dumb LCD

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