Question

In a circuit, where 5v is supplied, it goes to a 220 ohm resistor before leading to a switch. When the switch is pressed, it has a wire leading to a digital input pin (reads whether there is current or not) and a pull-down resistor which goes to ground. When the switch is connecting the current through, does the pull-down resistor effect the current going to the digital pin? The path pretty much splits in two, so I'm not betting it acts as a normal series circuit.. I can't have more than 25milli amps going to the digital pin, which is why I added the 220 ohm resistor before the button

Answer 1

so that, the current in theory should be limited to 23 milli amps before it passes through the button.. though I'm not positive on that either since it isn't a normal series circuit.

Answer 2

Since current takes the path of least resistance, the pull-down resistor takes none of the current- meaning that all 5v are going to the IO pin-- the 50-150ma limit is shown here: http://playground.arduino.cc/Main/ArduinoPinCurrentLimitations in both the 'sourcing' and the 'sinking'

And yet- here is a video of someone leading the 5V to a digital pin without a resistor (at 5min 10 seconds) https://www.youtube.com/watch?v=abWCy_aOSwY&index=3&list=PLA567CE235D39FA84

(I'd assume 1 ohm of natural resistance, which means the current amperage going into the pin equals 5 amps.. 5000 ma.. over 50 times what the digital input should be able to take. I guess I'm missing something.

Answer 3

Found out the 5v can be directly supplied to a digital input pin... case closed.. world makes sense again.