M37212M4 Datasheet, PDF (74/120 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER

MITSUBISHI MICROCOMPUTERS
M37212M4/M8–XXXSP, M37212M6–XXXSP/FP
M37212EFSP/FP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
with ON-SCREEN DISPLAY CONTROLLER
8.12. RESET CIRCUIT
When the oscillation of a quartz-crystal oscillator or a ceramic reso-
nator is stable and the power source voltage is 5 V ± 10 %, hold the
RESET pin at LOW for 2 µs or more, then return is to HIGH. Then, as
shown in Figure 8.12.2, reset is released and the program starts form
the address formed by using the content of address FFFF16 as the
high-order address and the content of the address FFFE16 as the
low-order address. The internal state of microcomputer at reset are
shown in Figures 8.2.3 to 8.2.6.
An example of the reset circuit is shown in Figure 8.12.1.
The reset input voltage must be kept 0.6 V or less until the power
source voltage surpasses 4.5 V.
Poweron
Power source voltage 0 V
4.5 V
Reset input voltage 0 V
0.6 V
1
5
M51953AL
4
3
0.1 µF
Fig. 8.12.1 Example of Reset Circuit
Vcc
RESET
Vss
Microcomputer
XIN
φ
RESET
Internal RESET
SYNC
Address
Data
?
?
01, S 01, S-1 01, S-2 FFFE FFFF
ADH,
ADL
?
?
?
?
? ADL ADH
Reset address from the vector table
32768 count of XIN
clock cycle (See note 3)
Notes 1 : f(XIN) and f(φ) are in the relation : f(XIN) = 2·f (φ).
2 : A question mark (?) indicates an undefined state that
depends on the previous state.
3 : Immediately after a reset, timer 3 and timer 4 are
connected by hardware. At this time, “FF16” is set
in timer 3 and “0716” is set to timer 4. Timer 3 counts down
with f(XIN)/16, and reset state is released by the timer 4
overflow signal.
Fig. 8.12.2 Reset Sequence
Rev. 1.0
73