HD404669 Datasheet, PDF(59/142 Page) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

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HD404669 Datasheet, PDF (59/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

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Timer mode register A (TMA: $008)

Bit

Initial value

Read/Write

Bit name

3

0

W

TMA3

2

0

W

TMA2

1

0

W

TMA1

0

0

W

TMA0

HD404669 Series

Source Input clock

TMA3 TMA2 TMA1 TMA0 prescaler frequency

Operating mode

0

0

0

0 PSS

2048tcyc

Timer A mode

1 PSS

1024tcyc

1

0 PSS

512tcyc

1 PSS

128tcyc

1

0

0 PSS

32tcyc

1 PSS

8tcyc

1

0 PSS

4tcyc

1 PSS

2tcyc

1

0

0

0 PSW

32tWcyc

1 PSW

16tWcyc

Time-base

mode

1

0 PSW

8tWcyc

1 PSW

2tWcyc

1

0

0â

1/2tWcyc

1â

Not used

1

Ãâ

Reset PSW and TCA

Ã : Donât care

Note: 1. tWcyc = 244.14 Âµs (when a 32.768-kHz crystal oscillator is used)

2. Timer counter overflow output period (seconds) = input clock period (seconds) Ã 256.

3. The division ratio must not be modified during time-base mode operation, otherwise an overflow

cycle error will occur.

Figure 40 Timer Mode Register A (TMA)

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