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74HC595 Help. Everything works until I daisy chain two together then no output!


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Hey guys your're my last resort on this! I seriously have no idea why this isn't working the way it should.

I'll do my best to try and explain what I have. Basically I have 2 74HC595's and I want to daisy chain them together. Right now I have both registers connected to my Atmega324 in the EXACT same way: data in pin branches to both, clock and latch pins branch to both. When they are connected like this everything works fine. Both my register outputs are exactly the same.

Here is the datesheet of 74HC595.

 

Now I know in order to daisy chain the two together I simply connect my serial output pin (9) of the first shift register to the data in pin (14) of the second register. BUT when I do that my outputs on BOTH of my shift registers just shut off. I get nothing at all.

I have each output pin of the shift registers connected to an LED. All I want to do is send a "pulse" down the line of 16 LEDs to test my theory.

If anyone has any ideas or even a sample code I can plug in to test I would REALLY appreciate it. I'm baffled!

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