I need to set myself up with a website so I can post links to example code. It appears I was one of the few that posted (past tense) example code on this web site. Even the great Nigel posted links to his site.
I'm currently tinkering with something kind of similar. I have an 18F2550 controlling one bi-color (red/green) 5x7 LED matrix (like the one at the top there, but red/green). It uses a 74HC4017N to handle the multiplexing for the 10 columns.
In this pic I'm still missing two transistors (2N2222A) and haven't wired the 14 rows to the PIC yet.
You probably already know, but you can get those from **broken link removed**. The heat sinks you have to source yourself though.
One caveat with those power supplies: You have to pay attention to which end you plug them in on the breadboard. Only one end works with correct polarity. Plug it in the other end and it's backward. I just recently build a VERY busy breadboard and left room at the wrong end for the power supply. Plugged in the power supply and turned it on. No magic smoke was released, luckily, but I caught it almost right away.
Surely in this case the only way you could give effective protection would be by putting a reverse biased diode across supplies (to negative) and therefore shorting the supply or am I missing an obvious solution here?
How about permanently marking the breadboard for a particular orientation?
I'm currently tinkering with something kind of similar. I have an 18F2550 controlling one bi-color (red/green) 5x7 LED matrix (like the one at the top there, but red/green). It uses a 74HC4017N to handle the multiplexing for the 10 columns.
In this pic I'm still missing two transistors (2N2222A) and haven't wired the 14 rows to the PIC yet.
Nice project you have reminded me I have got a corker of a future project, a board out of an old fruit machine with 36 5x7 display modules complete with some logic circuits to run the thing, must be serial data in but not sure how yet. I must attempt to work it out some day!
Nice project you have reminded me I have got a corker of a future project, a board out of an old fruit machine with 36 5x7 display modules complete with some logic circuits to run the thing, must be serial data in but not sure how yet. I must attempt to work it out some day!
I started out with two displays, but soon realized it was going to take all of those two breadboards just to fit the wiring for one. And it's not gonna be pretty!
Anyway, I'm having fun with it and learning some interesting things. My first schematic has already been trashed. It wouldn't have worked. Started building it and soon realized it was so wrong! So I'm happy that I didn't spend any more time on it than I did.
Surely in this case the only way you could give effective protection would be by putting a reverse biased diode across supplies (to negative) and therefore shorting the supply or am I missing an obvious solution here?
How about permanently marking the breadboard for a particular orientation?
I started out with two displays, but soon realized it was going to take all of those two breadboards just to fit the wiring for one. And it's not gonna be pretty!
Did you see the 8x8 matrix LEDs on the same page? I planned on trying something similar with one of those. Do you have a schematic? Even a scanned hand-drawn picture would help.
Time to order a bundle of stuff from Futurlec, are the component bundles (e.g. transistors) any good? Or should I order a bunch of separate ones?
Ha! She works! Red-only till I get my just-received transistors installed, but the multiplexing works perfect. Spent some time chasing my tail with it until I realized that RC4 and 5 are input-only. Moved that line to RC7 and away she went!
These LEDs are nice cherry red. Look what my camera turns them into! I have yet to find a way to color correct LEDs. Any attempt to correct LED color throws the rest of the pic way out of whack, so I just leave em. **broken link removed**