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3 clock selection register (ckscr), Clock selection register (ckscr) – FUJITSU F2MCTM-16LX User Manual

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CHAPTER 5 CLOCKS

5.3

Clock Selection Register (CKSCR)

The clock selection register (CKSCR) is used to switch among the main clock, PLL
clocks and subclock, also used to select an oscillation stabilization wait interval and a
PLL clock multiplier.

Configuration of the Clock Selection Register (CKSCR)

Figure 5.3-1 Configuration of the Clock Selection Register (CKSCR)

bit9

bit8

CS2

CS1

CS0

Multiplication rate select bit

Parenthesized values are examples calculated at

an oscillation clock (HCLK) frequency of 4 MHz.

0

0

0

1

×

HCLK (4 MHz)

0

0

1

2

×

HCLK (8 MHz)

0

1

0

3

×

HCLK (12 MHz)

0

1

1

4

×

HCLK (16 MHz)

1

1

0

6

×

HCLK (24 MHz)

1

1

1

Setting disabled

bit10

MCS

PLL clock select bit

0

Select PLL clock

1

Select main clock

bit11

SCS

Sub clock select bit

0

Select sub clock

1

Select main clock

bit13 bit12

WS1 WS0

Oscillation stabilization wait time select bit

Parenthesized values are examples calculated at an

oscillation clock (HCLK) frequency of 4 MHz.

0

0

2

10

/HCLK (approx. 256

µ

s)

0

1

2

13

/HCLK (approx. 2.05 ms)

1

0

2

17

/HCLK (approx. 32.77 ms)

1

1

2

15

/HCLK

(

approx.

8.19 ms, other than power-on reset)

2

16

/HCLK

(

approx.

16.38 ms, power-on reset only)

bit14

MCM

PLL clock operation bit

0

Operating in PLL clock

1

Operating in main clock or sub clock

bit15

SCM

Sub clock operation bit

0

Operating in sub clock

1

Operating in main clock or PLL clock

Address

15

14

13

12

11

10

9

8

Reset value

0000A1

H

SCM

MCM

WS1

WS0

SCS

MCS

CS1

CS0

11111100

B

R

R

R/W R/W R/W R/W R/W R/W

CS2(PSCCR register: bit8)

HCLK

: Oscillation clock

R/W

: Read/Write

R

: Read only

: Reset value