C504 查看數據表（PDF） - Siemens AG

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C504

8-bit Single-chip Microcontroller

Siemens AG 

C504

Timer / Counter 0 and 1

Timer/Counter 0 and 1 can be used in four operating modes as listed in table 4.

Table 4

Timer/Counter 0 and 1 Operating Modes

Mode Description

0

8-bit timer/counter with a

divide-by-32 prescaler

1

16-bit timer/counter

2

8-bit timer/counter with

8-bit autoreload

3

Timer/counter 0 used as one

8-bit timer/counter and one

8-bit timer

Timer 1 stops

Gate

X

TMOD

C/T M1

X0

Input Clock

M0 internal external (max)

0

f / OSC 12 × 32

f / OSC 24 × 32

X

X

1

1

f / OSC 12

X

X

0

0

f / OSC 12

f / OSC 24

f / OSC 24

X

X

1

1

f / OSC 12

f / OSC 24

In the “timer” function (C/T = ‘0’) the register is incremented every machine cycle. Therefore the

count rate is fOSC/12.

In the “counter” function the register is incremented in response to a 1-to-0 transition at its

corresponding external input pin (P3.4/T0, P3.5/T1). Since it takes two machine cycles to detect a

falling edge the max. count rate is fOSC/24. External inputs INT0 and INT1 (P3.2, P3.3) can be

programmed to function as a gate to facilitate pulse width measurements. Figure 5 illustrates the

input clock logic.

Figure 5

Timer/Counter 0 and 1 Input Clock Logic

Semiconductor Group

20

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