Only sample data every fourth tooth.

Use correct variable name.

Implement 4-window rpm averaging.

Hacky attempt at only updating rpm every four teeth.

According to maths, 0+4 = 4, not 3.

Try reading rpm only every crank revolution.

Maths dictate that something that has modulus 4 equal to 2 will never have modulus 12 equal to 0.

Clean up indentation.