pullups

[rikotech8]

Hi! I'm an amateur in writing codes on CCS and I'm wondering, what is the main purpose of the pullups function, when we use it, and why we need it? Some examples would help.
I hope someone understood me!


Thx. in advance!

[SherpaDoug]

The pull up resistors allow you to put a switch on a PIC pin without having to add an external resistor for the switch to work against. Better yet if you can switch off the pull ups when you are not reading the switches you can save battery power.
Pull ups can also stop unused pins from floating, therefore drawing excessive power. A digital input that happens to lie at an intermediate voltage level causes the input buffer to draw more power than it would at valid logic levels.
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