driving LED displays

Started by cc0x1 December 8, 2005
I was wondering if someone out there can offer some advice on how to
drive dot-matrix LED displays with the BX-24. I need to create a
simple scrolling text display using several of these displays. The
one possible caveat is that the text it will be displaying will be
from an embeeded web server (possibly the siteplayer).

I was searching old posts and noticed that someone was using the
Agilent HCMS-29xx series displays, which are the very same ones I am
looking at. If anyone can offer any help on interfaceing these with
BX-24 to creating scrolling displays, I would really appreciate it.

Thanks,
Carlos



> ... Agilent HCMS-29xx series displays...

Yes, I have a current project using those display modules. I cannot
provide the code I developed since its sale is pending but, if you have
questions as you proceed, I can probably help. They are very nice
small alpha displays. Tom


cc0x1 wrote:

> I was wondering if someone out there can offer some advice on how to
> drive dot-matrix LED displays with the BX-24. I need to create a
> simple scrolling text display using several of these displays. The
> one possible caveat is that the text it will be displaying will be
> from an embeeded web server (possibly the siteplayer).
>
> I was searching old posts and noticed that someone was using the
> Agilent HCMS-29xx series displays, which are the very same ones I am
> looking at. If anyone can offer any help on interfaceing these with
> BX-24 to creating scrolling displays, I would really appreciate it.

I haven't used these displays before but I know they can be cascaded for
a longer display. The basic idea is to convert characters into 5x7 dot
arrays using some kind of lookup table.

You can think of these displays as a huge shift register which should
tell you how to interface to it.BasicX as a ShiftOut function which
should meet your needs. Start slowly and try things out before being too
adventurous.

Mike
http://home.austin.rr.com/perks/micros/



> I was wondering if someone out there can offer some advice on how to
> drive dot-matrix LED displays with the BX-24.[]

I think as a starting point you can use the LED SCROLLING DISPLAY
from http://www.rafatronics.com/display.html. It has I2c and serial
ports, may be it is just what you are looking for, or you may pick up
some ideas.

-Yuri



Thanks Mike and Tom,

It seems fairly straightforward. If I have any questions once I start
programming it, i'll post again.

-Carlos []


I can, however, provide a font for the HP HCMS-29xx LED alphanumeric
display modules, which I transcribed from HP's application note for the
font. The font is organized as five bytes, each a column, top down,
right-to-left; that is, the last bit will appear in the upper-right
corner of the character. MSBs are invisible; only seven bits are
displayed in each column.

See
http://groups.yahoo.com/group/basicx/files/Datasheets-Appnotes-Examples-Drawings/LED/ Tom



Thanks so much Tom. I haven't deceided if I will use the HCMS-29xx or
the HDSP-253x, but this is of great help either way. BTW, other than
one being serial and the other being parallel, I don't really see much
of a difference between the HCMS and HDSP series, maybe you can tell
me. I'll just go with whichever one is easiest.

-Carlos --- In basicx@basi..., Tom Becker <gtbecker@r...> wrote:
>
> I can, however, provide a font []



> ... don't really see much of a difference between the HCMS and HDSP
series...

I haven't used the HDSP parallel parts but the documentation shows
something like a 19-pin interface for full control; that's beyond the
16 I/O pins of the BX-24 so you'd need to use a BX-01 or -35. You
could probably trim that down but it will still need many more pins
than a serial display will need.

Operating the display would be similar except that you'd pass it ASCII
in parallel instead of columns serially, so it should be much faster
to load.

The serial display can be seen in operation in the group Photos:
http://photos.groups.yahoo.com/group/basicx/lst?.dir=/Construction+Techniques/Light+Control+Film+on+LED+displays&.src=gr&.order=&.view=t&.done=http%3a//briefcase.yahoo.com/ Tom