1000 microseconds == 1 millisecond
1000 milliseconds == 1 second
60 seconds == 1 minute
interval = (currentTime - timeOfLastRcordedClock) / PPQ
interval = (1000000 - 500000) / 24
If the BPM is 120 then the average interval between quarter notes will be 500000
microseconds
If we want to send 24 pulses per quarter-note (PPQ) then the formula for the interval between pulses (in microseconds) would look like:
500000 / 24 = 20833.333333