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Topic: HC595N (Read 632 times) previous topic - next topic

svalls

I am playing with the shiftout tutorial with two HC595N, however I notice that when I power on the Arduino all the outputs of the HC595 are on.
Is there any other IC that when powered on is default to off, or any other way to connect the HC595?

Because if I connect it to (for example) motors, I can not tolerate that all the motors will be moving when I power on.

Grumpy_Mike

You can use the output enable pin pulled up to 5V with a 4K7 resistor. This will put the outputs into tristate mode until you put that pin down from the program. Likewise the outputs will be floating, pull them down with 10K so they look like a logic zero until you are ready to enable the outputs.

svalls

Thanks Grumpy_Mike for your fast reply.
I tried to put OE (Pin 13) to Vcc via 4K7 and also the outputs of the IC pull down via 10K. But with no success.

However I put the DS (pin 14) pulldown with 10K resistor and now it seems to work properly.
I don't know exactly what I made, as I was testing randomly.
Will this work?

Grumpy_Mike

Well on my data sheet pin 13 is the output enable, the DS (serial data) is on pin 14. So it looks like you are looking at a data sheet that labels things differently. So it looks like you are doing what I suggested all along.  :)

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