7470 datasheet(89/361 Pages) RENESAS

tên linh kiện	7470

Giải thích chi tiết về linh kiện	8-BIT SINGLE-CHIP MICROCOMPUTER 740 FAMILY / 7470 SERIES

PDF	361 Pages

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nhà sản xuất	RENESAS [Renesas Technology Corp]

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7470/7471/7477/7478 GROUP USER’S MANUAL

1-82

HARDWARE

1.12 Timers

Fig. 1.12.10 Relation between timer value change timing and read value change timing

(3) To select the CNTR pin input as Timer count source, the frequency of the CNTR count source should

satisfy the condition shown in Table 1.12.14.

1.12.5 Notes on use

(1) The contents of the Timer 12 mode register (T12M: Address 00F816) and the Timer 34 mode register

(T34M: Address 00F916) become “0016” at reset and each timer performs a count operation.

(2) Figure 1.12.10 shows the relation between Timer value change timing and read value change timing.

The Timer value changes at the rise of the count source, while the read value changes at the fall of

the count source. Accordingly, the read value may be larger than the real timer value by “1.”

Main clock

4MHz

8MHz

Upper boundary

1MHz

2MHz

Lower boundary

There is no

special restriction.

Frequency of the CNTR count source

Table 1.12.14 Frequency of CNTR

0116

0016

FF16

9816

9716

0216

0116

0016

FF16

9816

9716

Timer read value

Timer count source

Timer value

Interrupt request bit

Example: Writing “9916” into Timer 1

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