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标题: [求助]mc9s12dp256的脉冲累加器PACTL中的时钟？？ [打印本页]

作者: mwm008 时间: 2006-1-10 11:43 标题: [求助]mc9s12dp256的脉冲累加器PACTL中的时钟？？

16-Bit Pulse Accumulator Control Register (PACTL)

0

AEN

AMOD

EDGE

CLK1

CLK0

AOVI

AI

PAEN— Pulse Accumulator A System Enable

PAMOD— Pulse Accumulator Mode

PEDGE— Pulse Accumulator Edge Control

PAMOD

PEDGE

Pin Action

0

0

Falling edge

0

1

Rising edge

1

0

Div. by 64 clock enabled with pin high level

1

1

Div. by 64 clock enabled with pin low level

If the timer is not active (TEN = 0 in TSCR), there is no divide-by-64 since the ¸64 clock is generated by the timer prescaler.

CLK1	CLK0	Clock Source
0	0	Use timer prescaler clock as timer counter clock
0	1	Use PACLK as input to timer counter clock
1	0	Use PACLK/256 as timer counter clock frequency
1	1	Use PACLK/65536 as timer counter clock frequency

请问：PACLK时钟与Div. by 64 clock 时钟是什么关系，还有它们与总线时钟又是什么关系？？

　　　Div. by 64 clock的时钟，是不是总线时钟除64？？

先谢谢了！！

作者: strongchen 时间: 2006-1-10 15:58

你看一下《S12ECT_16B8CV1.pdf》的Figure 4-4，就会很明白了。Div.by 64 clock就是总线时钟除以64；PACLK是PACA的参考时钟，它的时钟源由PAMOD和PEDGE这两位来选择，即Table 3-5介绍的那样。

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PAMOD	PEDGE	Pin Action
0	0	Falling edge
0	1	Rising edge
1	0	Div. by 64 clock enabled with pin high level
1	1	Div. by 64 clock enabled with pin low level