R8CSLASH15 datasheet(61/277 Pages) RENESAS

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R8C/14 Group, R8C/15 Group

9. Clock Generation Circuit

Rev.2.10

Jan 19, 2006

Page 49 of 253

REJ09B0164-0210

9.4.1.1

High-Speed Mode

The main clock divided-by-1 (no division) provides the CPU clock. If the CM14 bit is set to “0” (low-

speed on-chip oscillator on) or the HRA00 bit in the HRA0 register is set to “1” (high-speed on-chip

oscillator on), the fRING and fRING128 can be used for timers X and C. When the HRA00 bit is set to

“1”, fRING-fast can be used for timer C. When the CM14 bit is set to “0” (low-speed on-chip oscillator

on), fRING-S can be used for the watchdog timer and voltage detection circuit.

9.4.1.2

Medium-Speed Mode

The main clock divided-by-2, -4, -8 or -16 provides the CPU clock. If the CM14 bit is set to “0” (low-

speed on-chip oscillator on) or the HRA00 bit in the HRA0 register is set to “1” (high-speed on-chip

oscillator on), the fRING and fRING128 can be used for timers X and C. When the HRA00 bit is set to

“1”, fRING-fast can be used for timer C. When the CM14 bit is set to “0” (low-speed on-chip oscillator

on), fRING-S can be used for the watchdog timer and voltage detection circuit.

9.4.1.3

High-Speed, Low-Speed On-Chip Oscillator Mode

The on-chip oscillator clock divided-by-1 (no division), -2, -4, -8 or -16 provides the CPU clock. The

on-chip oscillator clock is also the clock source for the peripheral function clocks. When the HRA00

bit is set to “1”, fRING-fast can be used for timer C. When the CM14 bit is set to “0” (low-speed on-

chip oscillator on), fRING-S can be used for the watchdog timer and voltage detection circuit.

9.4.2

Wait Mode

Since the CPU clock stops in wait mode, the CPU operated in the CPU clock and the watchdog timer

when count source protection mode is disabled stops. The main clock and on-chip oscillator clock do

not stop and the peripheral functions using these clocks maintain operating.

9.4.2.1

Peripheral Function Clock Stop Function

If the CM02 bit is set to “1” (peripheral function clock stops in wait mode), the f1, f2, f4, f8 and f32

clocks stop in wait mode. The power consumption can be reduced.

9.4.2.2

Entering Wait Mode

The microcomputer enters wait mode by executing the WAIT instruction.

9.4.2.3

Pin Status in Wait Mode

The status before entering wait mode is maintained.

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