HD6417144 RENESAS [Renesas Technology Corp], HD6417144 Datasheet - Page 304

• Manufacturer Part Number: HD6417144
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family/SH7144 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

11.
2. Free-Running Count Operation and Periodic Count Operation:
Rev.4.00 Mar. 27, 2008 Page 260 of 882
REJ09B0108-0400
Immediately after a reset, the MTU’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 TPU requests an interrupt. After overflow, TCNT starts counting up again from
H'0000.
Figure 11.4 illustrates 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 TPU requests an
interrupt. After a compare match, TCNT starts counting up again from H'0000.
Multi-Function Timer Pulse Unit (MTU)
H'FFFF
H'0000
CST bit
TCFV
TCNT value
Figure 11.4
Free-Running Counter Operation
Time