HD404374FT datasheet(83/161 Pages) RENESAS

83 / 161 page

HD404374/HD404384/HD404389/HD404082/HD404084 Series

Rev.5.00, Sep.11.2003, page 83 of 161

Timer C Operation

• Free-running/reload timer:

Free-running/reload timer operation, the input clock source, and the prescaler division ratio are selected

by means of timer mode register C1 (TMC1).

Timer C is initialized to the value written to timer write register C (TWCL, TWCU) by software, and

counts up by 1 each time the input clock is input. When the input clock is input after the timer C value

reaches $FF, overflow output is generated. Timer C is then set to the value in timer write register C

(TWCL, TWCU) if the reload timer function is selected, or to $00 if the free-running timer function is

selected, and starts counting up again.

Overflow output sets the timer C interrupt request flag (IFTC). This flag is reset by the program or by

an MCU reset.

For details, see figure 3, Interrupt Control Bit and Register Flag Area Configuration, and table 1, Initial

Values after MCU Reset.

• 16-bit timer operation:

When timer B overflow flag is selected as the clock source, timer C can be used as a 16-bit timer that

counts the timer B clock source pulses. In this case, since the timer B and timer C free-running/reload

settings are independent, the settings should be made to suit the purpose.

• Watchdog timer operation:

By using the timer C overflow output, timer C can be used as a watchdog timer for detecting program

runaway. The watchdog timer is enabled when the watchdog on flag (WDON) is set to 1, and generates

an MCU reset when timer C overflows. Usually, timer C initialization is performed by the program

before the timer C value reaches $FF, so controlling program runaway.

• Timer output operation:

With timer C, the R2

0/TOC pin is designated as the TOC pin by setting bit 0 of port mode register 3

(PMR3) to 1, and toggle waveform output or PWM waveform output can be selected by timer mode

 Toggle output

The operation is similar to that for timer B toggle output.

 PWM output

The operation is similar to that for timer B PWM output.

• Module standby:

The operation is similar to that for timer B module standby.

HD404374FT Datasheet(PDF) 83 Page - Renesas Technology Corp