Direct

Latency of directly hooking an input to a digital pin on a microcontroller

Measured by toggling a pin on the microcontroller in question, and then timing how long it takes for that signal to reach a target over USB.

Microcontroller	Sparkfun Pro Micro 5V	Sparkfun Pro Micro 3.3V	Arduino Uno
Usb Poll Rate	1 ms	1 ms	1 ms
Minimum	0.53 ms	0.53 ms	0.48 ms
Maximum	1.34 ms	1.35 ms	1.3 ms
Average	0.84 ms	0.84 ms	0.8 ms
Std dev	0.24 ms	0.24 ms	0.25 ms
%on time	96%	96%	96%
%1f skip	4%	4%	4%
%2f skip	0%	0%	0%
%3f skip	0%	0%	0%