Datasheet

Section 11 16-Bit Timer Pulse Unit (TPU)
Page 744 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
When compare match is selected as the TCNT clearing source, the TCNT counter for the
relevant channel performs periodic count operation. The TGR register for setting the period is
designated as an output compare register, and counter clearing by compare match is selected
by means of bits CCLR2 to CCLR0 in TCR. After the settings have been made, TCNT starts
count-up operation as a periodic counter when the corresponding bit in TSTR is set to 1. When
the count value matches the value in TGR, the TGF bit in TSR is set to 1 and TCNT is cleared
to H'0000.
If the value of the corresponding TGIE bit in TIER is 1 at this point, the TPU requests an
interrupt. After a compare match, TCNT starts counting up again from H'0000.
Figure 11.5 illustrates periodic counter operation.
TCNT value
TGR
H'0000
CST bit
TGF
Time
Counter cleared by TGR
compare match
Flag cleared by software or
DTC activation
Figure 11.5 Periodic Counter Operation