Hi everyone,
I have seen in a circuit had 12LEDs and 12Buttons before.
These buttons and LEDs has been controlled by only 3 pins thanks to 74HC595.
And I now need this circuit but don't have any idea how to make the circuit.
I would appreciate if you help me.
There are hundreds of previous discussions about microcontroller SR IO circuits, you may want to type in 74hc595 in search field above, or start with the similar threads indicated on the page bottom.
Yes, you're right but there are 24IOs and all of them aren't inputs. I know that it can control the maximum of 12inputs at the same time.(as 4x3keypad. = 7inputs)