SH7763 Datasheet, PDF (797/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 20 16-Bit Timer Pulse Unit (TPU)
(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 20.3 illustrates free-running counter operation.
TCNT value
H'FFFF
H'0000
CST bit
Time
TCFV
Figure 20.3 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. 1.00 Oct. 01, 2007 Page 731 of 1956
REJ09B0256-0100