A. The HRCAP has
some variation in performance, this results in a probability
distribution which is described using the following terms:
Accuracy: The time difference between the input
signal and the mean of the HRCAP’s
distribution.
Precision: The width of the HRCAP’s distribution,
this is given as a standard deviation.
Resolution: The minimum measurable
increment.
Figure 6-75 HRCAP Accuracy
Precision and Resolution
A. Typical core
conditions: All peripheral clocks are enabled.
B. Noisy core
supply: All core clocks are enabled and disabled with a
regular period during the measurement.
C. Fluctuations in
current and voltage on the VDD rail cause the standard
deviation of the HRCAP to rise. Care should be taken to
ensure that the VDD supply is clean, and that noisy internal
events, such as enabling and disabling clock trees, have
been minimized while using the HRCAP.
Figure 6-76 HRCAP Standard
Deviation Characteristics