SH7125_08 Datasheet, PDF (256/774 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 9 Multi-Function Timer Pulse Unit 2 (MTU2)
2. Free-Running Count Operation and Periodic Count Operation:
Immediately after a reset, the MTU2’s TCNT counters are all designated as free-running
counters. When the relevant bit in TSTR is set to 1 the corresponding TCNT counter starts up-
count operation as a free-running counter. When TCNT overflows (from H'FFFF to H'0000),
the TCFV bit in TSR is set to 1. If the value of the corresponding TCIEV bit in TIER is 1 at
this point, the MTU2 requests an interrupt. After overflow, TCNT starts counting up again
from H'0000.
Figure 9.5 illustrates free-running counter operation.
TCNT value
H'FFFF
H'0000
CST bit
Time
TCFV
Figure 9.5 Free-Running Counter Operation
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 CCLR0 to CCLR2 in TCR. After the settings have been made, TCNT starts
up-count 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 MTU2 requests an
interrupt. After a compare match, TCNT starts counting up again from H'0000.
Rev. 4.00 Jul. 25, 2008 Page 236 of 750
REJ09B0243-0400