HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 592

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 15
(b) Free-running count operation and periodic count operation
Immediately after a reset, the TPU'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. After overflow, TCNT starts counting up again from H'0000.
Figure 15.3 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
CCLR2 to CCLR0 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.
After a compare match, TCNT starts counting up again from H'0000.
Rev. 3.00 Jan. 18, 2008 Page 530 of 1458
REJ09B0033-0300
H'FFFF
H'0000
CST bit
TCFV
16-Bit Timer Pulse Unit (TPU)
TCNT value
Figure 15.3
Free-Running Counter Operation
Time