Idea that needs some help

Well im just starting to get into PIC's. Im working on Nigels tutorials.

I had an idea a while ago for my car alarm and some guy said he would help but blew me off, so maby this is a good place to start learnin.

I want a 50 led chaser. LOL
I have searched but i havent found anything that comes close to the scale im looking for. It would be awsome to have like a puchbutton that will change between 4 modes.

Like going from top to bottem, having 2 mini top to bottems, going from the top only, going from the bottem only.

I would really appreciate any help with this sort of project, as well as ANY input you may have.
~~Thanks

Isn't it usually possible to daisy chain several smaller chasers into one larger one? I'm sure audioguru will know

It's easy to daisy chain PIC's, but a multiplexed array of LED's (8x8) would give 64 LED's off a single PIC.

Sweet! Im sure i can manage 64 leds.... LOL
So where would a good starting point be?

BTW Nigel: Thanks alot for taking the time to write those tutorials. I just sent my designs off for a few of your board so i can work with nice professional boards.

markland556 said:

Sweet! Im sure i can manage 64 leds.... LOL
So where would a good starting point be?

Click to expand...

Look at the seven segment LED tutorial, that multiplexes 2x7, but could easily be increased to do 8x8 - you would need both NPN and PNP driver transistors in order to provide enough current for the displays. I would suggest using a 28 pin PIC, so you have 16 pins for the LED's (two ports) and extra pins for switches or serial I/O.

As well as doing what you asked, such a board would make a good individual module for a modular 'scrolling text' display.

You could reduce the pin requirement by 'charlieplexing', but this is more complicated, and limits the amount of current you can use per LED.

hmm, still a n00b, kinda understand but still a little lost.

I have some daisy-chained chaser circuits on my hard drive, but have never tried them. My chaser projects use 10 LEDs in a low voltage and low current circuit. The brief blinks from the LEDs are extremely bright but the duration is so short that the battery lasts a long time.

Use a PIC for the high number of LEDs and the patterns that you want.

Nigel Goodwin said:

... but a multiplexed array of LED's (8x8) would give 64 LED's off a single PIC.

Click to expand...

Using one MAX7219 driver chip from Maxim, connected to the PIC (in synchonous serial fashion) with 3 wires. Here's a link to a datasheet.
JB