I want to count pulses with an Arduino Uno. My pulses are nominally 5V but the actual signal fluctuates between 9V and 3V for about 2 Micro seconds before settling in to 5V for another 13 micro seconds. Can I read these pulses directly through the digital pins or should I use something like a voltage divider? Using a voltage divider (pair of resistors) that gets the peak voltage less than or equal to 5V results in the overall voltage becoming too low to count consistently (I count 50% less pulses per minute using the voltage divider). The frequency of the pulses I'm measuring is about 1 per second.
Maybe the bouncing between 9V and 3V for a couple of microseconds won't hurt the Arduino board (maybe that's normal for the beginning of a 5V signal) But I wanted to check before I count the unattenuated signals for any length of time.
If there's an alternative to a voltage divider, please mention that as well.