2 Oct
2008
2 Oct
'08
3:34 p.m.
Ethan Dicks wrote:
Not really. It's straight 8-bit with RD/WR/CS/addressing. If you don't need to
read from the display, ignore the nRD line (tie it high), then tie nWR and nCS
together (to save an I/O line).
That leaves you with a requirement for 8 data lines, one write strobe, five
address lines, a reset line and the "flash register access" line (effectively
another address line). So that's 16 lines. I wanted to wire mine up to a PIC
microcontroller, so I needed to save a few more I/O lines.
The obvious solution (and the one I used) was to use a 74LS164 shift register
to handle the data pins. Shift the data in (8 clocks), set the address and
strobe nWR. Job done. If you need to save more I/O lines, add another shift
register to handle the address and nFL lines. That brings the count down to
four -- nWR/nCS, LS164_CLK, LS164_DATA, and RESET.
Startup is a piece of cake -- you write a single byte to the Mode register,
then you just write characters to the display RAM. User defined characters are
just as easy -- you write the character address to one register, then write
five bytes of character data to consecutive CGRAM addresses.
Down for maintenance, unfortunately.
Aye, usually from 10PM to 7AM UK time. The words "pain in the backside" spring
to mind...
A bit on the
expensive side for what it is, but it does the job. I've been
using it with HP HDSP-2112 (green) 5x7 LED displays.
I have a few of those at home I got from a friend who worked at a place that
made avionics displays (when they cleared out buckets of old components).
I've never tried to talk to them, but I have the datasheet here. They look
interesting, but slightly complicated to talk to at the register level
(physical interfacing seems easy enough). One idea I had for them was the date portion of a
multi-time-zone clock
(we have several on the walls here out of necessity, and a desktop-sized
on seemed to be a good target). What have you been using yours for?
I've only used one -- it's in a hand-held rev-counter I built for testing
motor speed controllers. I'm working on the power supply for it now --
basically it's a lithium-ion battery pack from a digital camera (Canon NB-5L,
from the new Ixus series, ?10) wired to a MAX1811
charge controller, an
MC34063 step-up converter (to get +5V) and a PIC micro that
acts as a battery
charge monitor. The hard part is building a connector for the battery...
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/