38D2 datasheet(64/136 Pages) RENESAS

64 / 136 page

Rev.3.02

Apr 10, 2008

Page 64 of 131

REJ03B0177-0302

38D2 Group

• Oscillation External Output Function

The 38D2 group has the oscillation external output function to

output the rectangular waveform of the clock obtained by the

oscillation circuits from P41 and P40.

In order to validate the oscillation external output function, set

P40 or P41, or both to the output mode (set the corresponding

direction register to “1”).

The level of the XCOUT external output signal becomes “H” by

the P40/P41 oscillation output control bits (bits 0 and 1) of the

oscillation output control register (address 001016) in the

following states;

• the function to output the signal from the XCOUT pin externally

is selected

• the sub clock (XCIN

−XCOUT) is in the stop oscillating or stop

mode.

Likewise, the level of the XOUT external output signal becomes

“H” by the P40/P41 oscillation output control bits (bits 0 and 1)

of the oscillation output control register (address 001016) in the

following states;

• the function to output the signal from the XOUT pin externally

is selected

• the main clock (XIN

−XOUT) is in the stop oscillating or stop

mode.

<Note>

When the signal from the XOUT pin or XCOUT pin of the

oscillation circuit is input directly to the circuit except this MCU

and used, the system operation may be unstabilized.

In order to share the oscillation circuit safely, use the clock

output from P40 and P41 by this function for the circuits except

this MCU.

Fig. 63 Structure of oscillation output control register

Fig. 64 Block diagram of oscillation external output function

Oscillation output control register

(OSCOUT : address 001016)

P40/P41 oscillation output control bits

b1 b0

0 0 : P41, P40 = Normal port

0 1 : P41 = Normal port, P40 = XOUT

1 0 : P41 = Normal port, P40 = XCOUT

1 1 : P41 = XCOUT , P40 = XOUT

Not used (Do not write to “1”.)

STP instruction

XIN

XOUT

Interrupt request

Interrupt disable flag I

Reset

XIN-XOUT oscillation stop bit

(CPUM Bit 5)

P61/XCIN

P62/XCOUT

Port XC switch bit

(CPUM Bit 4)

P41/OOUT1

P40/OOUT0

P41 direction register

P40 direction register

OSCOUT control

P41 output latch

P40 output latch

Oscillation

output

selection

circuit

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