Im trying to learn input shift register to increase number of inputs for my Arduino. And in googling I found this schematic
I think its not for 74HC165, but I believe its almost same way for 165 also. But my concern or confusion is the resistors there. What is the purpose of those resistors there, which are connected to ground??
Best Answer
The inputs of CMOS logic parts (CD4000 series, 74HC, 74AC) are very high impedance, so if left unconnected may randomly appear as logic High or Low. With the switch open, the resistor holds the inputs Low, but allows a closed switch to pull the input High.
If you want the inputs to be High by default, you would connect the resistors between the input pin and the positive supply, with the switches connected between the input pin and Ground.