How can I correctly setup attachInterrupt() in this sketch?

[anon57585045]

@costalegre

// ESR reference coil function
void ref_coil()
{
noInterrupts (); // turn off Interrupts when counting
ref_coil_count++;
interrupts ();
}

No, you don't turn off interrupts inside an ISR. It's already done for you by the processor.