2010-05-01

HDSP-2000LP Arduino

A few years ago I bought some 4x 5x7 small LED displays in eBay. I though they looked really cool to be used in a front panel display, instead of using a single line LCD. The datasheet was actually easy to find but driving the display...well that's another story.
The initial objective was to incorporate these displays as front panel to the mini68k, as usual I try to prototype it with the Arduino. It ended up as being quite hard, you must compose the characters as "bitmap" graphics, then shift the 24 bits for "column" one of all the displays, then activate column one for 2ms... then repeat to column 2 to 5.
So first you must compose the combined display bitmap from the individual characters, then shift a sequence of bits and activate the respective column. To do it proper you must have in memory a bitmap for each character, compose the "screen" and the shift the bits and activate the columns in sequence.

As you can see from my first program... it didn't go well... unless you're the Predator and your personal nuke is counting down...
A few more head bangs against the wall et voilà...

Finally insanity takes over and I try to do a space invader... (the following photos are so crappy I forgot to get out of the light shade, late night)

inter character spacing is too wide to make multi-characters symbols (like infinity) unreadable... let alone the space invader that got cut in half... probably from a missile F-111...

The code is here, enjoy...

6 comments:

CommunitySteve said...
This comment has been removed by the author.
CommunitySteve said...

Hi,
Great project, but what components did you use? Is that a voltage regulator & how is it used?
Did you manage to connect more than one display to an Arduino?
Steve

J Silva said...

Hi Steve, thanks for commenting..
The voltage regulator is "a left over" from the SDCard experiment, it is not used for the display. I didn't try to connect more than one, I think one or two more (8 to 12 chars) is manageable, from then on bit-banging the bits one by one might have some noticeable flicker.
JS

Anonymous said...

Dumb question I am sure... but is that a capacitor between vcc and gnd?

qcope said...

Dumb question I am sure but is that a capacitor between vcc and gnd?

J Silva said...

Yes, I've used an old tantalum capacitor (the blue blob above the display 33uf, 16V).