From
crank_minper
This is the minimum time between trigger pulses. For this application where we use 2 trigger pulses per crank revolution it's 1/(2*8000/60)=0.00375s=3750us The authentic source (global.h) says 16 usec: uint8_t crank_minper;// Cranktigger period minimum (*16 usec)
The docs say this is the minimum period for the crank trigger (actually, between trigger teeth, so 180crankdeg for a 4cyl, even with many crankpulses). It is in 16us intervals.
It's a filter that limit the max trigger frequency.
So for a 60 tooth its 1/(60*8000/60)= 1/(8000) = 0.000125 = 125us