Mitsubishi microcomputers
M16C / 62A Group (80-pin)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Reset
Reset
There are two kinds of resets; hardware and software. In both cases, operation is the same after the reset.
(See “Software Reset” for details of software resets.) This section explains on hardware resets.
When the supply voltage is in the range where operation is guaranteed, a reset is effected by holding the
reset pin level “L” (0.2VCC max.) for at least 20 cycles. When the reset pin level is then returned to the “H”
level while main clock is stable, the reset status is cancelled and program execution resumes from the
address in the reset vector table.
The RAM is undefined at power on. The initial values must therfore be set. When a reset signal is applied
while the CPU is writing a value to the RAM, the value may be set as unknown due to the termination of the
CPU access.
Figure 1.6.1 shows the example reset circuit. Figure 1.6.2 shows the reset sequence.
5V
4.0V
V
CC
0V
5V
V
CC
RESET
RESET
0V
0.8V
Example when VCC = 5V
.
Figure 1.6.1. Example reset circuit
X
IN
More than 20 cycles are needed
Single chip
mode
RESET
BCLK 24cycles
BCLK
FFFFC16
Content of reset vector
Address
FFFFE16
Figure 1.6.2. Reset sequence
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RENESAS [ RENESAS TECHNOLOGY CORP ]
