Hitachi H8S/2646 Hardware Manual page 395

Phase Counting Mode Application Example: Figure 10-33 shows an example in which phase
counting mode is designated for channel 1, and channel 1 is coupled with channel 0 to input servo
motor 2-phase encoder pulses in order to detect the position or speed.
Channel 1 is set to phase counting mode 1, and the encoder pulse A-phase and B-phase are input
to TCLKA and TCLKB.
Channel 0 operates with TCNT counter clearing by TGR0C compare match; TGR0A and TGR0C
are used for the compare match function, and are set with the speed control period and position
control period. TGR0B is used for input capture, with TGR0B and TGR0D operating in buffer
mode. The channel 1 counter input clock is designated as the TGR0B input capture source, and
detection of the pulse width of 2-phase encoder 4-multiplication pulses is performed.
TGR1A and TGR1B for channel 1 are designated for input capture, channel 0 TGR0A and
TGR0C compare matches are selected as the input capture source, and store the up/down-counter
values for the control periods.
This procedure enables accurate position/speed detection to be achieved.
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