HD64F2145 datasheet(352/829 Pages) RENESAS

352 / 829 page

Rev. 2.0, 08/02, page 312 of 788

13.4.3

Measurement of 8-Bit Timer Divided Waveform Period

The timer connection facility, TMR_1, and the free-running timer (FRT) can be used to measure

the period of an IHI signal divided waveform. Since TMR_1 can be cleared by a rising edge of the

inverted IVI signal, the rise and fall of the IHI signal divided waveform can be synchronized with

the IVI signal. This enables period measurement to be carried out efficiently.

To measure the period of an IHI signal divided waveform, TCNT in TMR_1 is set to count the

external clock (IHI signal) pulses and to be cleared on the rising edge of the external reset signal

(inverse of the IVI signal). The value to be used as the division factor is written in TCORA, and

the TMO output method is specified by the OS bits in TCSR.

Examples of TCR and TCSR settings in TMR_1, and TCR and TCSR settings in the FRT are

shown in table 13.6, and the timing chart for measurement of the IVI signal and IHI signal divided

waveform periods is shown in figure 13.5. The period of the IHI signal divided waveform is given

by (ICRD(3) – ICRD(2))

× resolution.

HD64F2145 Datasheet(PDF) 352 Page - Renesas Technology Corp