Adafruit's best practices for their Neopixel LED strings say, "Place a 300 to 500 Ohm resistor between the Arduino data output pin and the input to the first NeoPixel."
Someone asked about the purpose of that resistor here and I'm reading about parasitic diodes and termination resistors to understand that more, but in a nutshell, why doesn't adding this resistor also drop voltage? In other words, if I had a 5V logic signal touching my Neopixel data line, won't adding this resistor in series make that signal fewer volts?
For example, if the Neopixel data circuit doesn't have any resistance then now I would expect 5V on one side of the resistor and 0V on the other... right? And if I have 0V going to the Neopixel data in, then how does signaling work at all? I'm super new to electronics but it just seems like this is the definition of a voltage divider circuit.
Also, if you didn't know about the 300-500 Ohm resistor, how would you choose that value? Is that based on an equation or just looking at something under a scope until it seems stable?
Thanks for helping, this is really puzzling me =)