M37221 Mitsubishi, M37221 Datasheet - Page 54

• Manufacturer Part Number: M37221
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER with ON-SCREEN DISPLAY CONTROLLER
• Manufacturer: Mitsubishi

CLOCK GENERATING CIRCUIT
The built-in clock generating circuit is shown in Figure 62. When the
STP instruction is executed, the internal clock
At the same time, timers 3 and 4 are connected in hardware and
“FF
as the timer 3 count source (set bit 0 of the timer 34 mode register to
“0” before the execution of the STP instruction). And besides, set the
timer 3 and timer 4 interrupt enable bits to disabled (“0”) before ex-
ecution of the STP instruction). The oscillator restarts when external
interrupt is accepted, however, the internal clock
until timer 4 overflows. Because this allows time for oscillation stabi-
lizing when a ceramic resonator or a quartz-crystal oscillator is used.
When the WIT instruction is executed, the internal clock
the “H” level but the oscillator continues running. This wait state is
released when an interrupt is accepted (Note). Since the oscillator
does not stop, the next instruction can be executed at once.
When returning from the stop or the wait state, to accept an interrupt,
set the corresponding interrupt enable bit to “1” before executing the
STP or the WIT instructions.
Note: In the wait mode, the following interrupts are invalid.
The circuit example using a ceramic resonator (or a quartz-crystal
oscillator) is shown in Figure 60. Use the circuit constants in accor-
dance with the resonator manufacture’s recommended values. The
circuit example with external clock input is shown in Figure 61. Input
the clock to the X
Fig. 62. Clock generating circuit block diagram
54
16
T34M : Timer 34 mode
” is set in the timer 3, “07
Selection gate :
(1) V
(2) CRT interrupt
(3) f(X
(4) Timer 1 interrupt using f(X
(5) Timer 2 interrupt using P2
(6) Timer 3 interrupt using P2
(7) Timer 4 interrupt using f(X
(8) Multi-master I
Connected to black
colored side at reset.
SYNC
register
IN
)/4096 interrupt
interrupt
IN
pin, and open the X
Interrupt request
Interrupt disable
2
C-BUS interface interrupt
16
X
IN
” is set in the timer 4. Select f(X
flag I
4
3
IN
IN
/TIM2 pin input as count source
/TIM3 pin input as count source
)/4096 as count source
)/2 as count source
OUT
X
Reset
OUT
pin.
STP instruction
stops at “H” level.
keeps its “H” level
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
1/2
stops in
1/8
IN
)/16
S
R
T34M0
M37221EF-XXXSP,M37221EFSP
Q
Fig. 60. Ceramic resonator circuit example
Fig. 61. External clock input circuit example
External oscillation circuit
WIT
instruction
19
X
M37221EF-XXXSP
T34M2
IN
with ON-SCREEN DISPLAY CONTROLLER
S
R
19
MITSUBISHI MICROCOMPUTERS
X
M 37221EF- XXXSP
I N
Q
Timer 3
C
I N
Vss
Vcc
Q
X
O U T
R
S
20
C
Timer 4
Internal clock
O U T
STP
instruction
Reset