Hitachi H8/3008 Hardware Manual page 233

Example of Phase Counting Mode: Figure 8.30 shows an example of operations in phase
counting mode. Table 8.5 lists the up-counting and down-counting conditions for 16TCNT2.
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.
16TCNT2 value
TCLKB
TCLKA
Figure 8.30 Operation in Phase Counting Mode (Example)
Table 8.5 Up/Down Counting Conditions
Counting
Direction Up-Counting
↑
TCLKB pin
TCLKA pin Low
Phase
difference
TCLKA
TCLKB
Figure 8.31 Phase Difference, Overlap, and Pulse Width in Phase Counting Mode
Counting up
↓
High
↑
High
Phase
difference
Overlap Overlap
Down-Counting
↓
Low HIgh
↓ ↓
Low
Pulse width
Phase difference and overlap:
Pulse width:
Counting down
↑
Low
↑
HIgh
Pulse width
at least 1.5 states
at least 2.5 states
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