64 LED Chaser - Advice needed.

Projects General Guidance
1

Gentlemen.

So my plan is to multiplex these 64 LEDs like they're in an 8x8 array even though they'll be mounted in a line.


(but each LED will have it's own current limiting resistor)

I think I'll use 2 74HC595 chips. One will control the LED cathodes and pull them to ground and the other 959 will bring the LED anodes high.

For pulling the cathodes to ground I can use a ULN2803 (basically 8 darlington transistors in one package). When the pin from the register brings the base of one of the ULN2803 channels high, current is allowed to flow to ground for that channel.

But what about the anodes? Is there a chip like the ULN2803 that will bring the channel high rather than low, when the base is brought high? Or should I just use 8 BC377 transistors? (I have alot in my parts bin)

What do you think? Would this be a good approach?

I know some of you will want to tell me to use the MAX7219CNG, but meh it's kinda expensive. And I'd like to build this with parts I already have. And I don't know how to use it. :blush:

Thanks
-Tony

2

transistors or you may just want to look at TPIC6B595's, they are much beefier than a normal 595 and saves added wire-hell

3

Brilliant! That'll work!
Can it be daisy chained with the normal 74HC595 chip?

4

according to the datasheet yes

5

just to offer..

(not too expensive)

10 pc:
http://www.ebay.com/itm/10PCS-IC-MAXIM-MAX7219CNG-IC-DRIVER-LED-DISPLAY-8DGT-24DIP-/270945635645?pt=LH_DefaultDomain_0&hash=item3f159e4d3d

1 pc:
http://www.ebay.com/itm/1PCS-IC-MAXIM-MAX7219CNG-IC-DRIVER-LED-DISPLAY-8DGT-24DIP-/280849405928?pt=LH_DefaultDomain_0&hash=item4163edd7e8

I have ordered these before. :wink:

6

Whoa! Right on man!
I'm going to order these asap!!! Thanks!

7

according to the datasheets.. these are the ones that do NOT support SPI..(MAX7219)

I think the MAX7221's... are the ones support SPI if that is what you want to use...etc

8

Hmm okay. I don't think I'm planning on using SPI. Truth be told I don't know how to use them at all. I'm guessing they're kinda like a shift register right? I'll research it a bit more eventually. But for the price I'll definitely pick up a few.

9

there are some links/tuts here outlining how to use them:

http://arduino.cc/playground/Main/LEDMatrix

http://arduino.cc/playground/Main/MAX72XXHardware

http://www.arduino.cc/playground/LEDMatrix/Max7219

there are others if you google..