SH7261 datasheet(493/1348 Pages) RENESAS

493 / 1348 page

Section 12 Multi-Function Timer Pulse Unit 2 (MTU2)

Rev. 2.00 Sep. 07, 2007 Page 461 of 1312

REJ09B0320-0200

(b)

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 12.5 illustrates free-running counter operation.

TCNT value

H'FFFF

H'0000

CST bit

TCFV

Time

Figure 12.5 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.

Figure 12.6 illustrates periodic counter operation.

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