ATMega328P How many interrupts per second can it handle?

60 interrupts per second is very slow for an ATmega328P running at 16 MHz. No problem. You probably don't even need an interrupt to keep up with that rate -- just keep sampling the signal (unless you've got lots of other things going on in your program that might cause you to miss it).

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The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected