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RESET CIRCUIT
To reset the microcomputer, RESET pin should be held at an “L”
level for 2 µs or more. Then the RESET pin is returned to an “H” level
(the power source voltage should be between VCC (min.) and 5.5 V,
and the quartz-crystal oscillator should be stable), reset is released.
After the reset is completed, the program starts from the address
contained in address FFFD16 (high-order byte) and address FFFC16
(low-order byte). Make sure that the reset input voltage meets VIL
spec. when a power source voltage passes VCC (min.).
MITSUBISHI MICROCOMPUTERS
38C2 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
RESET
Power source
VCC voltage
0V
Reset input
voltage
0V
Poweron
VIL spec.
RESET
VCC
Power source
voltage detection
circuit
Fig. 47 Reset circuit example
XIN
φ
RESET
Internal
reset
Address
Data
SYNC
Reset address from
vector table
?
?
?
?
FFFC FFFD ADH, ADL
ADL
ADH
XIN : about 8000 cycles
Note 1: The frequency relation of f(XIN) and f(φ) is f(XIN) = 8 • f(φ).
2: The question marks (?) indicate an undefined state that depends on the previous state.
Fig. 48 Reset sequence
46