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FUJITSU MB91460 SERIES FR60 User Manual

Page 276

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Chapter 18 Timebase Counter

7.Q&A

7. Q&A

7.1 How do I setup the oscillation stabilization wait time that is generated automatically?

Use the oscillation stabilization wait time selection bits (STCR.OS[1:0]). (The following lists likely scenarios
and the required settings.)

• F2: Main clock divided by 2, or subclock

• In the case of an INIT pin input, operation defaults to “00” (F2 x 2

1

=main clock divided by 4).

• For other resets and when recovering from stop mode, the operation is in accordance with the specified

clock (main or sub) and oscillation stabilization wait time (OS[1:0]) setting.

• The count is performed by the timebase counter.

• Once the time is selected, it is not initialized except by a settings initialization triggered by the external

INIT pin.

Scenario

Oscillation

stabilization wait

time selection bits

(OS[1:0])

Example oscillation stabilization wait time

after a reset (INIT) or on

recovering from stop mode

Oscillation

stabiliza-

tion

wait time

4.0MHz

Main clock

running

32.768kHz

Subclock

running

To not halt the main PLL or oscillator during stop mode

(No oscillation stabilization wait time required)

Set “00”.

Φ2 × 2

1

1.00

µs

61

µs

To not stop the oscillator during external clock input or

stop mode

(Main PLL lock wait time)

Set “01”.

Φ2 × 2

11

1.0ms

62.5ms

When using an oscillator with a fast stabilization time

such as a ceramic resonator

(Oscillation stabilization wait time (medium))

Set to “10”.

Φ2 × 2

16

32ms

2.0s

When using a standard quartz oscillator

(Oscillation stabilization wait time (long))

Set to “11”.

Φ2 × 2

22

2s

128s