I registered to ask a similar question, so I decided to try it in this thread. I've read the above links and, as someone who is tinkering with resistors for the first time since my 1980's Radio Shack kits, I feel like I haven't quite wrapped my head around the pull down resistor concept yet.
I'd appreciate a kick in the head from someone who can explain the theory behind it.
I understand the need for pin 2 (in the Arduino example above) to read a steady LOW rather than "floating," electrically connected to nothing and possibly picking up environmental interference. Hypothetically, if the circuit were never
going to be closed by the switch, pin 2 could just be connected by to GND and it would read LOW ... right? And the 10K resistor is doing exactly that when the switch is open?
Obviously, closing the switch with a direct connection instead of a resistor would short 5V to GND. Using the 10K resistor makes the path to ground "less interesting" when the switch is closed and the current goes for pin 2 instead ... right?
For some reason, I keep focusing on the resistor's role in the closed circuit (protecting from short) while all of the online explanations (and the very name "pull down resistor") focus on its role in pulling the voltage to a steady LOW when the circuit's open. Basically, I'm seeing it as a "short protection resistor" instead of a "pull down resistor." What am I missing that's causing me to think backwards?
Thanks in advance.