Hitachi H8/3032 Series Hardware Manual page 255

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.
TCLKB
TCLKA
Table 8-9 Up/Down Counting Conditions
Counting Direction
TCLKB
TCLKA
TCLKA
TCLKB
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TCNT2 value
Counting up
Figure 8-44 Operation in Phase Counting Mode (Example)
Up-Counting
High
Low
Phase Phase
difference difference
Overlap
Figure 8-45 Phase Difference, Overlap, and Pulse Width in Phase Counting Mode
Down-Counting
Low High
High
Pulse width
Phase difference and overlap:
Pulse width:
Overlap
240
Counting down
Time
Low
Low High
Pulse width
at least 1.5 states
at least 2.5 states