Have you considered using the full graphics/character functions of LCD
timing controller. I recently prototyped an LED graphics display (60 col
by 30 rows) using the Hitachi (HD61830B) for the timing and data, and
serial in parallel out shift registers for the drivers. To debug the
graphics controller commands, I used the PC parllel port. Now that this
idea works, I am interfacing to the 16C84. The HD61830B has a built in
character generator and also allows you read/write to the video memory
(with external RAM), adjust memory start address (horizontal, vertical
scrolling), cursor control. It can handle all displays up to VGA /4. Be
careful of the driver chip selection since the commons can sink quite a
bit of current if an entire row is selected. I used the 74LS164 (with
current limit resistor for the source) and discetes for the sinks. Just
use the last output to the next input to link the 164's together. This
method sure beats bit-banging all the data, clock, load pulses. By the
way, other graphics controller exist that have more functions but be
aware of controllers that have the LCD drivers built-in. These wont
work.



Jann P. Kaminski
UNIAX Corp.
6780 Cortona Dr.
Santa Barbara, CA 93117-3022
Tel: 805 562 9293
FAX: -9144
Email: jann@uniax.com
WWW: www.uniax.com


	
        ----------
        > From: GIBSON RJ <r164f@SMSERVER2.ULST.AC.UK>
        > To: PICLIST@MITVMA.MIT.EDU
        > Subject: ADVICE ON PICs
        > Date: Viernes 14 de Noviembre de 1997 12:35 PM
        > 
        > For my final year degree project I am going to
        > build an LED display matrix,capable of displaying
        > moving messages. Some sort of Microprocessor
        > system is needed to control the display matrix.
        > Because of the multiplexing method that is going
        > to be used to control the display,a fast PIC with
        > the following facilities is required :-
        > 
        > - plenty of I/O lines.
        > 
        > - an A/D converter (as it's also going to be
        > ÊÊconnected to a temperature sensor).
        > 
        > - Serial comms facilities to allow connection to
        > ÊÊa PC via RS 232 serial port.
        > 
        > - It must be capable of accessing external RAM as
        > ÊÊthis is where the binary patterns representing
        > ÊÊthe message will be stored.
        > 
        > I would appreciate any recommendations on what
        > type of PIC would be most suitable for this
        > application.