16 stage shift registers?

I've found: STP16C596

However it's availability is virtually zero. My goal is to have a matrix of 42 leds (on/off, no pwm needed).

I have also found the max7219, however since common annode RGB leds are much cheaper (about half the price), I would like to avoid the common cathode variety.

Is such a beast still available? Or are there alternatives that I have yet to find? Or am I boned, requiring CC leds and the 7219?


You can daisy chain normal shift registers.
Another possibility is multiplexing the leds.

Why don't you check out the A6276 16 bit shift register with constant current outputs. I used two of them in my 5x5x5 LED cube and obtained them from Newark Electronics. Avalible in DIP package as well.


However it's availability is virtually zero.

The reason is that they are no longer manufactured, so all you are going to have to do is find some one with old stock.

You can daisy chain normal shift registers. Another possibility is multiplexing the leds.

With normal sr's I would require 5, and I'd like to keep things as small as possible, using a 16 stage (or is it bit?) I could reduce that to 3.

I will be doing some reading up on multiplexing (another form of charlieplexing? or just a synonym?). If you have any decent resources, I'd love to see them :)

Another question would be, how feasible would it be to breadboard a small matrix for testing/learning? Looking at the schematics i've seen, It would be fairly difficult (or very messy wiring) to breadboard anything larger than a 3x3 matrix.

Multiplexing is hurting my brain ;)

You could lookup how manufactured LED matrices work: http://hackedgadgets.com/wp-content/LED_matrix.GIF

If you connect em like that, you'd only need 6+7 = 13 pins to control the LEDs.

Multiplexing isn't really hard to understand; in this case, you just light up all the LED's of one row, then the next, and the next, etc until you've lit all the rows. Then start at the first again. If you do this fast enough, you get what is called Persistence of View, the projected image of each row is persistent in your view for a brief moment. When the refresh rate is high enough, you get the idea of a complete image.

Everyone always looks for the really cheap chips.

Why not go for 2 M5451s. 35 constant current outputs each and you only need one resistor for all the outputs.


The problem is you're searching for 'shift registers'

what you're looking for is a serial linear led driver.

max6969 or similar. (Maxim is the company)

I picked up a 7x5 matrix and wired it direct as per the playground page, just to get my mind around the programming and logic being multiplexing.. I hooked up a pot to adjust the frame rate, and the only thing i can say (other than I now understand what is going on...) is...

Damn, aren't our brains amazing? ;)

darn, aren't our brains amazing?

Yes ;D