R8C2K datasheet(88/471 Pages) RENESAS

88 / 471 page

R8C/2K Group, R8C/2L Group

10. Clock Generation Circuit

Rev.1.10

Dec 21, 2007

Page 71 of 450

REJ09B0406-0110

10. Clock Generation Circuit

The clock generation circuit has:

• XIN clock oscillation circuit

• Low-speed on-chip oscillator

• High-speed on-chip oscillator

Table 10.1 lists the Specifications of Clock Generation Circuit. Figure 10.1 shows a Clock Generation Circuit. Figure

10.2 shows a Peripheral Function Clock. Figures 10.3 to 10.8 show clock associated registers.

NOTES:

1. These pins can be used as P4_6 or P4_7 when using the on-chip oscillator clock as the CPU clock while the

XIN clock oscillation circuit is not used.

2. Set the CM05 bit in the CM0 register to 1 (XIN clock stopped), and the CM13 bit in the CM1 register to 1 (XIN-

XOUT pin) when an external clock is input.

3. The clock frequency is automatically set to up to 20 MHz by a divider when using the high-speed on-chip

oscillator as the CPU clock source.

Table 10.1

Specifications of Clock Generation Circuit

Item

XIN Clock Oscillation Circuit

On-Chip Oscillator

High-Speed On-Chip Oscillator

Low-Speed On-Chip Oscillator

Applications

• CPU clock source

• Peripheral function clock

source

• CPU clock source

• Peripheral function clock

source

• CPU and peripheral function

clock sources when XIN clock

stops oscillating

• CPU clock source

• Peripheral function clock

source

• CPU and peripheral function

clock sources when XIN clock

stops oscillating

Clock frequency

0 to 20 MHz

Approx. 40 MHz(3)

Approx. 125 kHz

Connectable

oscillator

• Ceramic resonator

• Crystal oscillator

−−

Oscillator

connect pins

XIN, XOUT(1)

−(1)

Oscillation stop,

restart function

Usable

Oscillator status

after reset

Stop

Oscillate

Others

• Externally generated clock

can be input(2)

• On-chip feedback resistor

RfXIN (connected/ not

connected, selectable)

−−

R8C2K Datasheet(PDF) 88 Page - Renesas Technology Corp

R8C2K Datasheet(HTML) 88 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL