m38039mf-xxxsp Mitsumi Electronics, Corp., m38039mf-xxxsp Datasheet - Page 87

• Manufacturer Part Number: m38039mf-xxxsp
• Description: Single-chip 8-bit Cmos Microcomputer
• Manufacturer: Mitsumi Electronics, Corp.

CLOCK GENERATING CIRCUIT
The M38039FFSP/FP has two built-in oscillation circuits. An oscil-
lation circuit can be formed by connecting a resonator between
X
cordance with the resonator manufacturer’s recommended values.
No external resistor is needed between X
feed-back resistor exists on-chip. However, an external feed-back
resistor is needed between X
Immediately after power on, only the X
oscillating, and X
Frequency Control
(1) Middle-speed mode
The internal clock
set, this mode is selected.
(2) High-speed mode
The internal clock
(3) Low-speed mode
The internal clock
If you switch the mode between middle/high-speed and low-
speed, stabilize both X
is required for the sub clock to stabilize, especially immediately af-
ter power on and at returning from stop mode. When switching the
mode between middle/high-speed and low-speed, set the fre-
quency on condition that f(X
(4) Low power dissipation mode
The low power consumption operation can be realized by stopping
the main clock X
bit 5 of the CPU mode register to “1.” When the main clock X
restarted (by setting the main clock stop bit to “0”), set sufficient
time for oscillation to stabilize.
IN
Note
and X
OUT
(X
IN
CIN
CIN
in low-speed mode. To stop the main clock, set
is half the frequency of X
is half the frequency of X
is the frequency of X
and X
and X
IN
and X
COUT
COUT
IN
CIN
) > 3f(X
CIN
). Use the circuit constants in ac-
pins function as I/O ports.
and X
oscillations. The sufficient time
CIN
COUT
IN
).
IN
oscillation circuit starts
.
divided by 8. After re-
IN
IN
CIN
.
and X
.
OUT
since a
IN
is
Oscillation Control
(1) Stop mode
If the STP instruction is executed, the internal clock
“H” level, and X
stabilizing time set after STP instruction released bit is “0,” the
prescaler 12 is set to “FF
oscillation stabilizing time set after STP instruction released bit is
“1,” set the sufficient time for oscillation of used oscillator to stabi-
lize since nothing is set to the prescaler 12 and timer 1.
After STP instruction is released, the input of the prescaler 12 is
connected to count source which had set at executing the STP in-
struction, and the output of the prescaler 12 is connected to timer
1. Set the timer 1 interrupt enable bit to disabled (“0”) before ex-
ecuting the STP instruction. Oscillator restarts when an external
interrupt is received, but the internal clock
CPU (remains at “H”) until timer 1 underflows. The internal clock
is supplied for the first time, when timer 1 underflows. Therefore
make sure not to set the timer 1 interrupt request bit to “1” before
the STP instruction stops the oscillator. When the oscillator is re-
started by reset, apply “L” level to the RESET pin until the
oscillation is stable since a wait time will not be generated.
(2) Wait mode
If the WIT instruction is executed, the internal clock
“H” level, but the oscillator does not stop. The internal clock
starts when an interrupt is received or reset. Since the oscillator
does not stop, normal operation can be started immediately after
the clock is restarted.
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
IN
and X
MITSUBISHI MICROCOMPUTERS
CIN
16
” and timer 1 is set to “01
oscillators stop. When the oscillation
3803/3804 Group
is not supplied to the
16
.” When the
stops at an
stops at an
re-
87