LED displays (TIL305, TIL308, etc.)

[Philip Pemberton]

Ethan Dicks wrote:
>> http://uk.farnell.com/178186/optoelectronics/product.us0?sku=visualux-2711xg1-5&_requestid=365374
> 
> 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).

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.

> 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/