1.1 Terminology

This document uses the term "accuracy" as determined by the accuracy of the clock frequency and granularity of measurement. Higher granularity equates to a smaller resolution. To get a more accurate measurement, choose a clock with high accuracy and high frequency for smaller granularity and higher resolution.

Another term that is used is “measurement uncertainty”. It is uncertain when the timer will stop relative to the pulse edge: it may stop exactly when the pulse edge occurs, or it may be as much as one clock later. The uncertainty is one full clock cycle.

As seen below (Figure 1), the resolution of the timer greatly affects the resultant measurement of the pulse.

Figure 1-1. Quantization Error When Determining the Associated Timer Value to a Certain Pulse Width. The Timer Increments at a Rate of 1 ns