> From: Thomas McGahee <tom_mcgahee@SIGMAIS.COM>
> One of the tricks that I use is to latch
> two of the columns and the row select bits and then
> put the last column out direct (not latched).
> That saves me one set of latches.
> I use 74373 style tristate latches. I drive
> standard size LEDs.

I had built before a similar display but I had used 74164
which had no tristate.  What I did was to turn-off
momentarily the scanning column during shifting of data.
All 74164s are cascaded so only 2 pins (CLK and DATA)
are used for inputs and 7 for scanning.  I had to use
'164 because it is the only available at the local store.
It was made with a 6805 micro.


> Data is received over a single pin serial line and
> transmitted over a second single pin serial line. This
> allows me to connect the "output" of one PIC driver module to the
> "input" of the next. Currently I use a portable PC to
> input the data to the first (rightmost) Pic driver module.

Before I made the 6805 interface I used a PC to test the
display module using its parallel port. I made the test
program using qbasic using graphics mode for the character
generation.


> I wrote up a program in Foxpro that allows me to create
> custom characters up to 7x8.

I used Excel to map the characters by putting '1' on the
cells and making the column width smaller so it may look
like a 5x7 char.  Custom chars are easily made this way
and no other programming is needed only by just making the
right formula.


Rgds,
Reggie