[sci.electronics] Alphanumeric LED driver

paulc@boulder.Colorado.EDU (Paul Connally) (06/28/89)

	Many thanks to all those who responded to my posting.
All the solutions I received were very enlightening but I have one
final question to this problem.

	I've decided to purchase a BCC-180 multitasking single board
computer from Circuit Cellar Ink.  The reason for this is that I have
some other processes that I'll definitely need it for (I know it would
be a waste just to program LED's with it!).  

	It has 48-bits of parallel I/O which will be plenty to multiplex
the LED segments with.  My question is, can I directly connect the anodes/cathodes , 74148 encoder, and the 7445 decoder to the parallel I/O lines.
The chips that the CPU (an HD64180) uses for these are 8255's.

	Or am I going bout this entirely wrong in connecting to the
parallel I/O?

	The CPU board also has an 8-bit BCC-bus, 2 asynch. serial ports, and
1 clocked serial port.

Paul Connally            	paulc@boulder.colorado.edu
University of Colorado  	High Voltage Electron Microscope Lab
MCDB  -  Box 347 		"A higher potential for 
Boulder, CO  80309		                 better penetration."

mmm@cup.portal.com (Mark Robert Thorson) (06/29/89)

The simplest output (though an expensive one) is through a serial interface.
There are many LED and LCD modules which have a one-line display which
receive data as an ASCII-encoded TTL signal.  This eliminates the need for
your computer to scan the display 30 times per second.