Hitachi H8S/2378, H8S/2378R Series Hardware Manual page 597

Phase Counting Mode Application Example: Figure 11.29 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 TGRC_0 compare match; TGRA_0 and
TGRC_0 are used for the compare match function, and are set with the speed control cycle and
position control cycle. TGRB_0 is used for input capture, with TGRB_0 and TGRD_0 operating
in buffer mode. The channel 1 counter input clock is designated as the TGRB_0 input capture
source, and detection of the pulse width of 2-phase encoder 4-multiplication pulses is performed.
TGRA_1 and TGRB_1 for channel 1 are designated for input capture, channel 0 TGRA_0 and
TGRC_0 compare matches are selected as the input capture source, and the up/down-counter
values for the control cycles are stored.
This procedure enables accurate position/speed detection to be achieved.
Edge
TCLKA
detection
TCLKB
circuit
Figure 11.29 Phase Counting Mode Application Example
Channel 1
TCNT_1
TGRA_1
(speed cycle capture)
TGRB_1
(position cycle capture)
TCNT_0
TGRA_0
(speed control cycle)
TGRC_0
(position control cycle)
TGRB_0 (pulse width capture)
TGRD_0 (buffer operation)
Channel 0
+
-
+
-
Rev. 1.0, 09/01, page 553 of 904