M16C30_02 Datasheet, PDF (15/178 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Reset
Mitsubishi microcomputers
M16C / 30 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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 value must therefore 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 1.5.1 shows the example reset circuit. Figure 1.5.2 shows the reset sequence.
RESET
VCC
Example when VCC = 5V.
5V
VCC
0V
5V
RESET
0V
Figure 1.5.1. Example reset circuit
4.0V
0.8V
More than 20 cycles of XIN are needed.
XIN
Microprocessor
mode BYTE = “H”
More than 20 cycles are needed
RESET
BCLK 24cycles
BCLK
Address
FFFFC16
FFFFD16
FFFFE16
Content of reset vector
RD
WR
CS0
Microprocessor
mode BYTE = “L”
Address
FFFFC16
FFFFE16
Content of reset vector
RD
WR
CS0
Single chip
mode
Address
FFFFC16
Content of reset vector
FFFFE16
Figure 1.5.2. Reset sequence
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