3822 datasheet(52/328 Pages) RENESAS

52 / 328 page

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SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS

3822 Group

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 2.5 V and

5.5 V, and the oscillation should be stable), reset is released. In or-

der to give the XIN clock time to stabilize, internal operation does

not begin until after 8200 XIN clock cycles (timer 1 and timer 2 are

connected together and 512 cycles of f(XIN)/16) are complete. Af-

ter 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 is less than 0.5 V for VCC of

2.5 V (Extended operating temperature version: the reset input

voltage is less than 0.6V for VCC of 3.0V).

Fig. 36 Internal state of microcomputer after reset

Fig. 35 Example of reset circuit

(Note)

0.2VCC

Note. Reset release voltage : VCC = 2.5V

(Extended operating temperature version : 3.0V)

Power on

VCC

RESET

VCC

RESET

Power source voltage

detection circuit

Reset input

voltage

Power source

voltage

(000116) • • •

Timer Y (low)

Port P0 direction register

Port P1 direction register

Port P2 direction register

PULL register B

Timer Y (high)

Serial I/O control register

UART control register

Timer X (high)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(000316) • • •

(000516) • • •

(001716) • • •

(001A16) • • •

(001B16) • • •

(002016) • • •

(002116) • • •

(002216) • • •

(002316) • • •

(002416) • • •

(002516) • • •

(002616) • • •

(002716) • • •

(002816) • • •

(002916) • • •

(002A16) • • •

Address

Timer X (low)

Timer 1

Timer 2

Timer 3

Timer X mode register

Timer Y mode register

Timer 123 mode register

φ output control register

0016

(000F16) • • •

1 1 10 00

Serial I/O status register (001916) • • • 1 0 00 00

Port P4 direction register

Port P5 direction register

Port P6 direction register

(000916) • • •

(000B16) • • •

(000D16) • • •

(25)

(26)

(27)

(003416) • • •

(003816) • • •

(003916) • • •

A-D control register

Segment output enable register

LCD mode register

PULL register A

(001616) • • • 0 0 00 10

Note ! : Undefined

The contents of all other registers and RAM are undefined

after reset, so they must be initialized by software.

(28)

(29)

(30)

(31)

(32)

(33)

(34)

(003A16) • • •

(003B16) • • •

(003C16) • • •

(003D16) • • •

(003E16) • • •

Interrupt edge selection register

CPU mode register

Interrupt request register 1

Interrupt request register 2

Interrupt control register 1

Interrupt control register 2

Processor status register

Program counter

1 0 0 1 00

Contents of address FFFC 16

(PS)

(PCH)

(PCL)

Contents of address FFFD 16

(003F16) • • •

0 0 0010

0016

( 1 )

( 2 )

( 3 )

( 4 )

( 5 )

( 6 )

( 7 )

( 8 )

( 9 )

! !

FF16

0116

FF16

0016

Port P7 direction register

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