Wait Mode - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group
10.4.1.1 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), fRING and fRING128 can be used as timers X and C. When the HRA00 bit is set to 1,
fRING-fast can be used as 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.
10.4.1.2 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), fRING and fRING128 can be used as timers X and C. When the HRA00 bit is set to 1, fRING-
fast can be used as 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.
10.4.1.3 High-Speed and Low-Speed On-Chip Oscillator Modes
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 as 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.
10.4.2

Wait Mode

Since the CPU clock stops in wait mode, the CPU, which operates using the CPU clock and the
watchdog timer when count source protection mode is disabled stop. The main clock and on-chip
oscillator clock do not stop and the peripheral functions using these clocks continue operating.
10.4.2.1 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. This reduces power consumption.
10.4.2.2 Entering Wait Mode
The MCU enters wait mode when the WAIT instruction is executed.
10.4.2.3 Pin Status in Wait Mode
The status before wait mode was entered is maintained.
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
Page 64 of 233
10. Clock Generation Circuit