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 6-62 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 1.2-V rail cause the standard
deviation of the HRCAP to rise. Care should be taken to
ensure that the 1.2-V supply is clean, and that noisy
internal events, such as enabling and disabling clock trees,
have been minimized while using the HRCAP.
Figure 6-63 HRCAP Standard
Deviation Characteristics