38D5 datasheet(59/141 Pages) RENESAS

59 / 141 page

Rev.3.01

Aug 08, 2007

Page 59 of 134

REJ03B0158-0301

38D5 Group

CLOCK OUTPUT FUNCTION

A system clock

φ can be output from I/O port P72. The triple

function of I/O port, timer 2 output function and system clock

output function are controlled by the clock output control register

(address 0FF316) and the timer 2 output selection bit of the timer

12 mode register (address 002516).

In order to output a system clock

φ from I/O port P72, set the

timer 2 output selection bit to “1” and P72 clock output control

bits of the clock output control register to “01”. In order to output

the same signal as oscillation frequency of sub clock XCIN, set

the P72 clock output control bits to “10”. When the clock output

function is selected, a clock is output while the direction register

of port P72 is set to the output mode.

P72 is switched to the port output or the output (timer 2 output or

the clock output) except port at the cycle after the timer 2 output

selection bit is switched.

Fig. 54 Structure of clock output control register

Fig. 55 Block diagram of Clock output function

Other function registers

[RRF register (RRFR)]

The RRF register (address 001216) is the 8-bit register and does

not have the control function.

As for the value written in this register, high-order 4 bits and

low-order 4 bits interchange.

It is initialized after reset.

Fig. 56 Structure of RRF register

Clock output control register

(CKOUT : address 0FF316)

P72 clock output control bits

b1b0

0 0: Timer 2 output

0 1:

φ frequency signal output

1 0: XCIN frequency signal output

1 1: Not available

Not used (returns “0” when read)

Timer 2 latch (8)

Timer 2 (8)

1/2

T2OUT output edge

switch bit

“0”

“1”

P72 latch

Timer 2 output selection bit

P72 direction register

P72/T2OUT/CKOUT

Timer 12 mode register (address 002516)

T12M

Timer 2 output selection bit

0 : I/O port

1 : Timer 2 output

System clock

Timer 2 output selection bit

XCIN

“00”

“01”

“10”

P72 clock output

control bits

RRF register

DB4 data storage

DB5 data storage

DB6 data storage

DB7 data storage

DB0 data storage

DB1 data storage

DB2 data storage

DB3 data storage

(RRFR : address 001216)

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