M30302MC 데이터 시트보기 (PDF) - Renesas Electronics

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M30302MC

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Renesas Electronics 

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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