My apologies for a rather newbie question, but I am trying to convert an industrial sensor design using an end of life NEC / Renesas chip to something that's actually still made. For prototyping purposes I'm using an Arduino Zero board with the SAMD21G18A before designing my own hardware. My problem is that I cannot configure a working 16 bit counter that I can read periodically. The pulses are completely random so the current design just counts them over a specific time period (30 or 10 seconds) and then produces an average counts per minute. ARM based processors are still new to me so I'd appreciate any help.