r5f21346mnfp Renesas Electronics Corporation., r5f21346mnfp Datasheet - Page 161

• Manufacturer Part Number: r5f21346mnfp
• Description: Single-chip Mcus Incorporates The R8c Cpu Core
• Manufacturer: Renesas Electronics Corporation.

R8C/34M Group
R01UH0131EJ0100 Rev.1.00
Jun 21, 2011
9.7.1.1
9.7.1.2
9.7.1.3
9.7.1.4
The XIN clock divided by 1 (no division), 2, 4, 8, or 16 is used as the CPU clock. If the CM14 bit is set to 0
(low-speed on-chip oscillator on) or the FRA00 bit in the FRA0 register is set to 1 (high-speed on-chip
oscillator on), fOCO can be used for timer RA.
Also, if the FRA00 bit is set to 1, fOCO40M can be used for timer RC and timer RD.
If the CM14 bit is set to 0 (low-speed on-chip oscillator on), fOCO-S can be used for the voltage detection
circuit.
The XCIN clock divided by 1 (no division), 2, 4, 8, or 16 is used as the CPU clock.
In this mode, low consumption operation is enabled by stopping the XIN clock and the high-speed on-chip
oscillator, and by setting the FMR27 bit in the FMR2 register to 1 (low-current-consumption read mode
enabled). When the CPU clock is set to the XCIN clock divided by 1 (no division), 2, 4, or 8, low-current-
consumption read mode can be used. However, do not use low-current-consumption read mode when the
frequency of the selected CPU clock is 3 kHz or below. After setting the divide ratio of the CPU clock, set the
FMR27 bit to 1.
Also, if the FRA00 bit is set to 1, fOCO40M can be used for timer RC and timer RD.
If the CM14 bit is set to 0 (low-speed on-chip oscillator on), fOCO-S can be used for the voltage detection
circuit.
To enter wait mode from low-speed clock mode, lower consumption current in wait mode is enabled by setting
the VCA20 bit in the VCA2 register to 1 (internal power low consumption enabled).
To reduce the power consumption, refer to 33. Reducing Power Consumption.
The high-speed on-chip oscillator is used as the on-chip oscillator clock when the FRA00 bit in the FRA0
register is set to 1 (high-speed on-chip oscillator on) and the FRA01 bit in the FRA0 register is set to 1. The on-
chip oscillator divided by 1 (no division), 2, 4, 8, or 16 is used as the CPU clock. If the FRA00 bit is set to 1,
fOCO40M can be used for timer RC and timer RD.
Also, if the CM14 bit is set to 0 (low-speed on-chip oscillator on), fOCO-S can be used for the voltage detection
circuit.
When the high-speed on-chip oscillator mode is selected as the system clock, do not enter stop mode while bits
CM37 and CM36 in the CM3 register is 00b (MCU exits with the CPU clock used immediately before entering
wait or stop mode).
If the CM14 bit in the CM1 register is set to 0 (low-speed on-chip oscillator on) and the FRA01 bit in the FRA0
register is set to 0, the low-speed on-chip oscillator is used as the on-chip oscillator clock. At this time, the on-
chip oscillator clock divided by 1 (no division), 2, 4, 8 or 16 is used as the CPU clock. The on-chip oscillator
clock is also the clock source for the peripheral function clocks. If the FRA00 bit is set to 1, fOCO40M can be
used for timer RC and timer RD.
Also, if the CM14 bit is set to 0 (low-speed on-chip oscillator on), fOCO-S can be used for the voltage detection
circuit.
In this mode, low consumption operation is enabled by stopping the XIN clock and the high-speed on-chip
oscillator, and by setting the FMR27 bit in the FMR2 register to 1 (low-current-consumption read mode
enabled). When the CPU clock is set to the low-speed on-chip oscillator clock divided by 4, 8, or 16, low-
current-consumption read mode can be used. After setting the divide ratio of the CPU clock, set the FMR27 bit
to 1.
To enter wait mode from low-speed clock mode, lower consumption current in wait mode is enabled by setting
the VCA20 bit in the VCA2 register to 1 (internal power low consumption enabled).
To reduce the power consumption, refer to 33. Reducing Power Consumption.
High-Speed Clock Mode
Low-Speed Clock Mode
High-Speed On-Chip Oscillator Mode
Low-Speed On-Chip Oscillator Mode
9. Clock Generation Circuit
Page 129 of 740