252
Example of Phase Counting Mode: Figure 8-44 shows an example of operations in phase
counting mode. Table 8-9 lists the up-counting and down-counting conditions for TCNT2.
In phase counting mode both the rising and falling edges of TCLKA and TCLKB are counted. The
phase difference between TCLKA and TCLKB must be at least 1.5 states, the phase overlap must
also be at least 1.5 states, and the pulse width must be at least 2.5 states. See figure 8-45.
TCNT2 value
Counting up
Counting down
Time
TCLKB
TCLKA
Figure 8-44 Operation in Phase Counting Mode (Example)
Table 8-9 Up/Down Counting Conditions
Counting Direction
Up-Counting
Down-Counting
TCLKB
High
Low
Low
High
TCLKA
Low
High
High
Low
TCLKA
TCLKB
Phase
difference
Phase
difference
Pulse width
Pulse width
Overlap
Overlap
Phase difference and overlap:
Pulse width:
at least 1.5 states
at least 2.5 states
Figure 8-45 Phase Difference, Overlap, and Pulse Width in Phase Counting Mode