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Q & a, 2 how do i select the external clock – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 35 Free-Run Timer

7.Q & A

7. Q & A

7.1 What are the types of the internal clock, and how do I select?

There are 4 types of internal clocks, and these are set by the clock selection bit (TCCS.ECLK) and the count
clock bit (TCCS.CLK [1:0]).

7.2 How do I select the external clock?

Set with clock selection bits (TCCS.ECLK), data direction bits, and (extra) port function bits.

7.3 How do I enable / disable the count operation of the free-run timer?

Set with count operation bits (TCCS.STOP).

Internal clock

Setting

Count period

Clock selection

Bit (ECLK)

Count clock bit

(CLK [1:0])

F

CLKP

=

32MHz

F

CLKP

= 16MHz

To select F

CLKP

/4

Set to “0”

Sets to “00”

125 ns

250 ns

To select F

CLKP

/16

Set to “0”

Set to “01”

0.5

µs

1

µs

To select F

CLKP

/32

Set to “0”

Set to “10”

1

µs

2

µs

To select F

CLKP

/64

Set to “0”

Set to “11”

2

µs

4

µs

To use the external

clock input

Setting

Pins

Count

Cycle

Free-run Timer 0-7

The clock
selection
bit (ECLK)
to “1”

The port function bit
(PFRxy.z)
to “1”

The extra port
function bit
(EPFRxy.z}
to “1”

CK0-
CK7

Over 2/F

CLKP

Operation

Count operation bit (STOP)

To enable the free-run timer

Set to “0”

To stop the free-run timer

Set to “1”