Mitsubishi M34282M2-XXXGP, M34282M1-XXXGP, M34282E2GP Datasheet

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

DESCRIPTION

The 4282 Group enables fabrication of 8 × 7 key matrix and has
the followin timers;

• an 8-bit timer which can be used to set each carrier wave and
has two reload register

• an 8-bit timer which can be used to auto-control and has a
reload register.

FEATURES

• Number of basic instructions ............................................. 68

• Minimum instruction execution time ............................ 8.0

(at f(X

IN) = 4.0 MHz, system clock = f(XIN)/8)

• Supply voltage ................................................. 1.8 V to 3.6 V

• Subroutine nesting ..................................................... 4 levels

Product

M34282M1-XXXGP
M34282M2-XXXGP
M34282E2GP

ROM (PROM) size

(× 9 bits)
1024 words
2048 words
2048 words

µ

• Timer

Timer 1 ................................................................... 8-bit timer

(This has a reload register and carrier wave output auto-control
function)

Timer 2 ................................................................... 8-bit timer

(This has two reload registers and carrier wave output function)

• Logic operation function (XOR, OR, AND)

• RAM back-up function

• Key-on wakeup function (ports D

• I/O port (ports D, E, G, CARR) .......................................... 16

• Oscillation circuit .....................................Ceramic resonance

s

• Watchdog timer

• Power-on reset circuit

• Voltage drop detection circuit ......................... Typical:1.50 V

(system reset)

4–D7, E0–E2, G0–G3) .... 11

APPLICATION

Various remote control transmitters

RAM size

(× 4 bits)
48 words
64 words
64 words

Package

20P2E/F-A
20P2E/F-A
20P2E/F-A

ROM type

Mask ROM
Mask ROM

One Time PROM

PIN CONFIGURATION (TOP VIEW)

VS

S

E2
E1

XIN

U

XO

T

E0
G0
G1
G2
G3

10

1
2

M

3 4 2 8 2 M x - X X X G

3
4
5
6
7
8

P

9

20
1 9
18
17
1 6
15
1 4

1 3
1 2
1 1

DD

V
CARR

D0
D1

D2
D3
D4

D5
D6
D

7

Outline 20P2E/F-A

BLOCK DIAGRAM

A

M

( 4 8 , 6 4 w o r d s

✕

4 b i t s

)

R

O

M

( 1 0 2 4 , 2 0 4 8 w o r d s

✕

9 b i t s

)

7

2 0 s e r i e

s

C

P U c o r

e

M

e m o r

y

/

O

p

o

r

t

I

n t e r n a l p e r i p h e r a l f u n c t i o

n

T

i

m

e

r

/

R

e

m

o

t

e

-

c

o

n

t

r

o

l

c

a

r

r

i

e

r

-

w

a

v

e

o

u

t

p

u

t

T

i m e r 1 ( 8 b i t s , c a r r i e r w a v e o u t p u t c o n t r o l

)

T

i m e r 2 ( 8 b i t s , c a r r i e r w a v e g e n e r a t i o n

)

S

y

s

t

e

m

c

l

o

c

k

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e

n

e

r

a

t

i

o

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u

i

t

X

I

N

-

X

O

U

T

(

N o t e

)

R

e

g

i

s

t

e

r

B

(

4

b

i

t

s

)

R

e

g

i

s

t

e

r

A

(

4

b

i

t

s

)

e

g

i

s

t

e

r

D

(

3

b

i

t

s

)

R

e

g

i

s

t

e

r

E

(

8

b

i

t

s

)

S

t a c k r e g i s t e r S K ( 4 l e v e l s

)

A

L U ( 4 b i t s

)

o

r

t

D
4

o

r

t

G
4

P

o r t

E
2

4

1

W

a t c h d o g t i m e r ( 1 4 b i t s

)

R

e s e t ( v o l t a g e d r o p d e t e c t i o n c i r c u i t

)

N

o

t

e

:

P

R

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M

2

0

4

8

w

o

r

d

s

✕

9

b

i

t

s

,

R

A

M

6

4

w

o

r

d

s

✕

4

b

i

t

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f

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b

u

i

l

t

-

i

n

P

R

O

M

v

e

r

s

i

o

n

.

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

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PERFORMANCE OVERVIEW

Parameter
Number of basic instructions
Minimum instruction execution time
Memory sizes

Input/Output
ports

Timer

Subroutine nesting
Device structure
Package
Operating temperature range
Supply voltage
Power
dissipation
(typical value)

ROM

M34282M2/E2
M34282M1

RAM

M34282M2/E2
M34282M1

0–D3

D

Output

D4–D7

I/O

E0–E2

Input

E0, E1

Output

G0–G3

I/O

CARR

Output
Timer 1
Timer 2

Active mode

RAM back-up mode

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Function

68

µ

s (f(XIN) = 4.0 MHz, system clock = f(XIN)/8, VDD = 3 V)

8.0
2048 words ✕ 9 bits
1024 words ✕ 9 bits
64 words ✕ 4 bits
48 words ✕ 4 bits
Four independent output ports
Four independent I/O ports with the pull-down function
3-bit input port with the pull-down function
2-bit output port (E
4-bit I/O port with the pull-down function
1-bit output port; CMOS output
8-bit timer with a reload register
8-bit timer with two reload registers
4 levels (However, only 3 levels can be used when the TABP p instruction is executed)
CMOS silicon gate
20-pin plastic molded SSOP (20P2E/F-A)
–20 °C to 85 °C

1.8 V to 3.6 V
400 µA

IN) = 4.0 MHz, system clock = f(XIN)/8, VDD = 3 V)

(f(X

µ

A (at room temperature, VDD = 3 V)

0.1

0, E1)

PIN DESCRIPTION

Pin

DD

V
VSS
XIN

XOUT
D0–D3

D4–D7

E0–E2

G0–G3

CARR

Name
Power supply
Ground
System clock input

System clock output
Output port D

I/O port D

I/O port E

I/O port G

Carrier wave output
for remote control

Input/Output

—
—

Input

Output
Output

I/O

Output

Input

I/O

Output

Function
Connected to a plus power supply.
Connected to a 0 V power supply.
I/O pins of the system clock generating circuit. Connect a ceramic resonator
between pins X
and XOUT.
Each pin of port D has an independent 1-bit wide output function. The output
structure is P-channel open-drain.
1-bit I/O port. For input use, set the latch of the specified bit to “0.” When the built­in pull-down transistor is turned on, the key-on wakeup function using “H” level
sense and the pull-down transistor become valid. The output structure is P-channel
open-drain.

0, E1) output port. The output structure is P-channel open-drain.

2-bit (E
3-bit input port. For input use (E
When the built-in pull-down transistor is turned on, the key-on wakeup function
using “H” level sense and the pull-down transistor become valid. Port E
input-only port and has a key-on wakeup function using “H” level sense and pull­down transistor.
4-bit I/O port. For input use, set the latch of the specified bit to “0.” The output structure
is P-channel open-drain. When the built-in pull-down transistor is turned on, the key­on wakeup function using “H” level sense and pull-down transistor become valid.
Carrier wave output pin for remote control. The output structure is CMOS circuit.

IN and XOUT. The feedback resistor is built-in between pins XIN

0, E1), set the latch of the specified bit to “0.”

2 has an

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3

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

CONNECTIONS OF UNUSED PINS

Pin

0–D7

D
E0, E1

Open or connect to V
Set the output latch to “1” and open, or

connect to V
E2
G0–G3

Open or connect to V

Set the output latch to “1” and open, or

connect to V

Notes 1: Ports D4–D7: Set the bit 2 (PU02) of the pull-down control register PU1 to “0” by software and turn the pull-down transistor

OFF.

2: Set the corresponding bits of the pull-down control register PU0 to “0” by software and turn the pull-down transistor OFF.

(Note in order to set the output latch to “1” to make pins open)

• After system is released from reset, a port is in a high-impedance state until the output latch of the port is set to “1” by software.
Accordingly, the voltage level of pins is undefined and the excess of the supply current may occur.

• To set the output latch periodically is recommended because the value of output latch may change by noise or a program run away
(caused by noise).

Connection

DD pin (Note 1).

DD pin (Note 2).

SS pin.

DD pin (Note 2).

(Note when connecting to V

SS and VDD)

• Connect the unused pins to V

PORT FUNCTION

Port

Port D

Port E

Port G

Port CARR

0–D3

D

D4–D7

E0
E1

E2

G0–G3

CARR

Pin

SS or VDD at the shortest distance and use the thick wire against noise.

Input/
Output
Output

(4)

Output structure

P-channel open-drain

Control

bits

1 bit

Control
instructions
SD
RD

Control

registers

CLD

I/O
(4)

SD
RD

PU1

CLD
SZD

I/O

P-channel open-drain

(2)

Output:

2 bits

OEA
IAE

PU0

Input:

Input

3 bits

IAE

(1)
I/O
(4)

Output

(1)

P-channel open-drain

CMOS

4 bits

1 bit

OGA
IAG

SCAR
RCAR

PU0

Remark

Pull-down function and
key-on wakeup function
(programmable)

Pull-down function and
key-on wakeup function
(programmable)

Pull-down function and
key-on wakeup function
(programmable)

DEFINITION OF CLOCK AND CYCLE

• System clock (STCK)
The system clock is the source clock for controlling this product.
It can be selected as shown below whether to use the CCK
instruction.

CCK instruction
When not using
When using

4

System clock

f(X

IN)/8

IN)

f(X

Instruction clock

IN)/32

f(X

IN)/4

f(X

• Instruction clock (INSTCK)
The instruction clock is a signal derived by dividing the system
clock by 4, and is the basic clock for controlling CPU. The one
instruction clock cycle is equivalent to one machine cycle.

• Machine cycle
The machine cycle is the cycle required to execute the
instruction.

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PORT BLOCK DIAGRAMS

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4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

SD instruction
RD instruction

SD instruction
RD instruction

Skip decision (SZD instruction)

Register A

A

(Note 3)

A

Key-on wakeup input

Register A

A

(Note 3)

Key-on wakeup input

Register Y

CLD instruction

DecoderRegister Y

CLD instruction

Key-on wakeup

j

OEA

instruction

j

Register A

Key-on wakeup input

j

OGA

instruction

A

j

D
T

A

2

D
T

Decoder

Q

IAE instruction

Q

IAG instruction

S

Q

R

(Note 2)

(Note 3)

IAE instruction

PU1

PU0

PU0

S

Q

R

i

j

2

(Note 1)

(Note 1)

Pull-down transistor

(Note 1)

Pull-down
transistor

Pull-down
transistor

Pull-down transistor

(Note 1)

(Note 1)

Ports D0–D3

Ports D4–D7 (Note 5)

Ports E0, E1 (Note 5)

Port E2 (Note 5)

Ports G0, G1 (Note 5)

Register A

k

A

(Note 4)

instruction

A

k

Key-on wakeup input

SCAR instruction

RCAR instruction

(from timer 2)

Timer 1 underflow signal

OGA

CARRYD

Q

D
T

CAR flag

V1

IAG instruction

SRQ

2

(Note 1)

Ports G2, G3 (Note 5)

Pull-down transistor

PU0

3

CARRY

(to timer 1)

(Note 1)

Port CARR

Q

D

V1

R

T

Carrier wave output control signal

0

Notes 1:

This symbol represents a parasitic diode.

2: i represents bits 0 to 3.
3: j represents bits 0, 1.
4: k represents bits 2, 3.
5: Applied voltage must be less than VDD.

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5

FUNCTION BLOCK OPERATIONS
CPU

(1) Arithmetic logic unit (ALU)

The arithmetic logic unit ALU performs 4-bit arithmetic such
as 4-bit data addition, comparison, and bit manipulation.

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

<Carry>

(CY)

(M(DP))

Addition

ALU

(2) Register A and carry flag

Register A is a 4-bit register used for arithmetic, transfer,
exchange, and I/O operation.
Carry flag CY is a 1-bit flag that is set to “1” when there is a
carry with the AMC instruction (Figure 1).
It is unchanged with both A n instruction and AM instruction.
The value of A
instruction (Figure 2).
Carry flag CY can be set to “1” with the SC instruction and
cleared to “0” with the RC instruction.

(3) Registers B and E

Register B is a 4-bit register used for temporary storage of 4­bit data, and for 8-bit data transfer together with register A.
Register E is an 8-bit register. It can be used for 8-bit data
transfer with register B used as the high-order 4 bits and
register A as the low-order 4 bits (Figure 3).

(4) Register D

Register D is a 3-bit register.
It is used to store a 7-bit ROM address together with register
A and is used as a pointer within the specified page when the
TABP p, BLA p, or BMLA p instruction is executed (Figure 4).

0 is stored in carry flag CY with the RAR

(A)

<Result>

Fig. 1 AMC instruction execution example

<Set>

SC instruction

<Clear>

RC instruction

CY A3A2A1A

<Rotation>

RAR instruction

A

0

CY A3A2A

Fig. 2 RAR instruction execution example

Register B Register A

B3B2B1B

TAB instruction

0

A3A2A1A

TEAB instruction

Register E

ER7ER6ER5ER4ER3ER2ER1ER

0

1

0

0

TABP p instruction

Specifying address

PC

H

p3p2p1p

Immediate field

value p

Fig. 4 TABP p instruction execution example

0

DR2DR1DR

The contents

of register D

PC

A3A2A1A

0

The contents

of register A

TABE instruction

B3B2B1B

Register B Register A

Fig. 3 Registers A, B and register E

0

A3A2A1A

TBA instruction

0

ROM

8

40

Low-order 4 bits

L

0

Middle-order 4 bits

Register A (4)

Register B (4)

Most significant 1 bit

Carry flag CY (1)

URS flag (1)

URSC instruction

6

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(5) Most significant ROM code reference enable flag (URS)

URS flag controls whether to refer to the contents of the most
significant 1 bit (bit 8) of ROM code when executing the TABP
p instruction. If URS flag is “0,” the contents of the most
significant 1 bit of ROM code is not referred even when
executing the TABP p instruction. However, if URS flag is “1,”
the contents of the most significant 1 bit of ROM code is set to
flag CY when executing the TABP p instruction (Figure 4).
URS flag is “0” after system is released from reset and returned
from RAM back-up mode. It can be set to “1” with the URSC
instruction, but cannot be cleared to “0.”

(6) Stack registers (SKs) and stack pointer (SP)

Stack registers (SKs) are used to temporarily store the contents
of program counter (PC) just before branching until returning
to the original routine when;

• performing a subroutine call, or

• executing the table reference instruction (TABP p).

Stack registers (SKs) are four identical registers, so that
subroutines can be nested up to 4 levels. However, one of
stack registers is used when executing a table reference
instruction. Accordingly, be careful not to over the stack. The
contents of registers SKs are destroyed when 4 levels are
exceeded.
The register SK nesting level is pointed automatically by 2-bit
stack pointer (SP).
Figure 5 shows the stack registers (SKs) structure.
Figure 6 shows the example of operation at subroutine call.

(7) Skip flag

Skip flag controls skip decision for the conditional skip
instructions and continuous described skip instructions.
Note : The 4282 Group just invalidates the next instruction

when a skip is performed. The contents of program
counter is not increased by 2. Accordingly, the number
of cycles does not change even if skip is not performed.
However, the cycle count becomes “1” if the TABP p,
RT, or RTS instruction is skipped.

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4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Program counter (PC)

SK
SK
SK

SK

0
1
2

3

(SP) ← 0
(SK
(PC) ← SUB1

Executing RT

instruction

0

is destroyed.

0

) ← 0001

16

(PC) ← (SK0)
(SP) ← 3

(SP) = 0
(SP) = 1
(SP) = 2

(SP) = 3

Subroutine

SUB1 :

Executing BM

instruction

Stack pointer (SP) points “3” at reset or
returning from RAM back-up mode. It points “0”
by executing the first BM instruction, and the
contents of program counter is stored in SK
When the BM instruction is executed after four
stack registers are used ((SP) = 3), (SP) = 0
and the contents of SK

Fig. 5 Stack registers (SKs) structure

Main program

Address
0000

16

NOP

16

BM SUB1

0001
000216 NOP

NOP

RT

0

.

·

·

·

Returning to the BM instruction execution

Note:

address with the RT instruction, and the BM
instruction is equivalent to the NOP instruction.

Fig. 6 Example of operation at subroutine call

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4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

(8) Program counter (PC)

Program counter (PC) is used to specify a ROM address (page
and address). It determines a sequence in which instructions
stored in ROM are read. It is a binary counter that increments
the number of instruction bytes each time an instruction is
executed. However, the value changes to a specified address
when branch instructions, subroutine call instructions, return
instructions, or the table reference instruction (TABP p) is
executed.
Program counter consists of PC
which specifies to a ROM page and PC

H (most significant bit to bit 7)

L (bits 6 to 0) which

specifies an address within a page. After it reaches the last
address (address 127) of a page, it specifies address 0 of the
next page (Figure 7).
Make sure that the PC

H does not exceed after the last page of

the built-in ROM.

(9) Data pointer (DP)

Data pointer (DP) is used to specify a RAM address and
consists of registers X and Y. Register X specifies a file and
register Y specifies a RAM digit (Figure 8).
Register Y is also used to specify the port D bit position.
When using port D, set the port D bit position to register Y
certainly and execute the SD, RD, or SZD instruction (Figure

9).

Program counter (PC)

p3p2p1p0a6a5a4a3a2a1a

PC

H

Specifying

PC

L

Specifying address

page

Fig. 7 Program counter (PC) structure

Data pointer (DP)

X1X0Y3Y2Y1Y

Register Y (4)

Register X (2)

0

Specifying RAM file

0

Specifying
RAM digit

Fig. 8 Data pointer (DP) structure

Specifying bit position

Set

D

5

7

1

Port D output latch

1

01

0

Register Y (4)

D

Fig. 9 SD instruction execution example

D

0

8

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PROGRAM MEMORY (ROM)

The program memory is a mask ROM. 1 word of ROM is
composed of 9 bits. ROM is separated every 128 words by the
unit of page (addresses 0 to 127).

Table 1 ROM size and pages

Product

M34282M2/E2

M34282M1

ROM size (✕ 9 bits)

2048 words
1024 words

Pages

16 (0 to 15)

8 (0 to 7)

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

087654321

16

0000

F

16

007
008016

00

FF

16

010016
017

F

16

018016

Subroutine special page

Page 0
Page 1
Page 2
Page 3

Page 2 (addresses 0100
subroutine calls. Subroutines written in this page can be called
from any page with the 1-word instruction (BM). Subroutines
extending from page 2 to another page can also be called with
the BM instruction when it starts on page 2.
ROM pattern of all addresses can be used as data areas with
the TABP p instruction.

16 to 017F16) is the special page for

DATA MEMORY (RAM)

1 word of RAM is composed of 4 bits, but 1-bit manipulation
(with the SB j, RB j, and SZB j instructions) is enabled for the
entire memory area. A RAM address is specified by a data
pointer. The data pointer consists of registers X and Y. Set a
value to the data pointer certainly when executing an instruction
to access RAM.
Table 2 shows the RAM size. Figure 11 shows the RAM map.

Table 2 RAM size

Product

M34282M2/E2

M34282M1

64 words ✕ 4 bits (256 bits)
48 words ✕ 4 bits (192 bits)

RAM size

07

FF

16

Fig. 10 ROM map of M34282M2/E2

RAM 64 words ✕ 4 bits (256 bits)

Register X

0

1

0
1
2
3
4
5
6
7
8

Register Y

9
10
11
12
13
14
15

Page 15

23

48 words
M34282M1

Fig. 11 RAM map

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64 words

M34282M2/E2

9

TIMERS

The 4282 Group has the programmable timer.

• Programmable timer
The programmable timer has a reload register and enables
the frequency dividing ratio to be set. It is decremented from a
setting value n. When it underflows (count to n + 1), a timer 1
underflow flag is set to “1,” new data is loaded from the reload
register, and count continues (auto-reload function).

FF

16

n: Counter initial value

Count starts

n

1st underflow 2nd underflow

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4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Reload Reload

The contents of counter

00

16

n+1 count n+1 count

Timer 1 underflow flag

“1”
“0”

Fig. 12 Auto-reload function

The 4282 Group timer consists of the following circuit.

• Timer 1 : 8-bit programmable timer

• Timer 2 : 8-bit programmable timer

These timers can be controlled with the timer control registers
V1 and V2.
Each timer function is described below.

Table 3 Function related timer

Circuit

Timer 1

Timer 2

14-bit timer

Structure

8-bit programmable
binary down counter
8-bit programmable
binary down counter
14-bit fixed frequency

Count source

• Carrier wave output (CARRY)

• Bit 5 of watchdog timer

IN)

• f(X

IN)/2

• f(X

• Instruction clock

Frequency

dividing ratio

1 to 256

1 to 256

16384

A skip instruction is executed

Use of output signal

• Carrier wave output control

• Carrier wave output

• Watchdog timer

• Timer 1 count source

Time

Control
register

V1

V2

10

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MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

CARRY

V1

X

IN

V1

0

1

0
1

0
1

(TAB1)

1/2

SCAR instruction

RCAR instruction

(Note 1)

Reload register R1 (8)

(T1AB)

Register B Register A

V2

0 (Note 1)

V2

1

0

0

1

1

(TAB2)

CAR flag

SQ
R

Timer 1 (8)

(Note 2)

Register B

Reload register R2H (8)

3

V2

(T2R2L)

(Note 3)

(T2AB)

Reload register R2L (8)

Register B

(T2HAB)

Timer 2(8)

(T2AB)

(TAB1)

Register A

Reload control circuit

Register A

CARRY
(to timer 1)

SNZT1 instruction

T1F

Timer 1 underflow signal
(to port CARR)

T

R

V2

2

(TAB2)

Q

SNZT2
instruction

T2F

T2F

Port CARR

CARRYD
(to port CARR)

Timer 1 underflow signal

X

IN

CCK instruction

Initializing signal

(Note 3)

INSTCK

Fig. 13 Timers structure

V1

2

Frequency divider
(divided by 8)

Synchronous

QS

circuit

R

Initializing signal

14-bit timer (WDT)

WRST instruction

Initializing signal

(Note 4)

DTQ

V1

R

(Note 4)

5

130

WDF1 WDF2

Carrier wave output control signal

0

STCK (System clock)

Frequency divider
(divided by 4)

Notes 1: Counting is stopped by clearing to “0.”

2: When the T1AB instruction is executed after V1

writing is performed only to reload register R1.

3: The data of reload register R2L set with the T2AB instruction

can be also written to timer 2 with the T2R2L instruction.

4: The initializing signal is output at reset or RAM back-up mode.

INSTCK
(Instruction clock)

System reset

0

is set to “1,”

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11

Table 4 Control registers related to timer

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Timer control register V1

2

V1

V11

V10

V13

V12

V11

V10

Note: “W” represents write enabled.

(1) Control registers related to timer

• Timer control register V1

• Timer control register V2

Carrier wave output auto-control bit

Timer 1 count source selection bit

Timer 1 control bit

Timer control register V1

Carrier wave “H” interval expansion bit

Carrier wave generation function control bit

Timer 2 count source selection bit

Timer 2 control bit

Register V1 controls the timer 1 count source and auto­control function of carrier wave output from port CARR by
timer 1. Set the contents of this register through register A
with the TV1A instruction.

Register V2 controls the timer 2 count source and the carrier
wave generation function by timer. Set the contents of this
register through register A with the TV2A instruction.

at reset : 0002 Wat RAM back-up : 0002

Auto-control output by timer 1 is invalid

0

Auto-control output by timer 1 is valid

1

Carrier wave output (CARRY)

0

Bit 5 of watchdog timer (WDT)

1

Stop (Timer 1 state retained)

0

Operating

1

at reset : 00002 Wat RAM back-up : 00002

To expand “H” interval is invalid

0

To expand “H” interval is valid (when V2

1

Carrier wave generation function invalid

0

Carrier wave generation function valid

1

IN)

f(X

0

IN)/2

f(X

1

Stop (Timer 2 state retained)

0

Operating

1

2=1 selected)

(2) Precautions

Note the following for the use of timers.

• Count source

Stop timer 1 or timer 2 counting to change its count source.

• Watchdog timer

Be sure that the timing to execute the WRST instruction in
order to operate WDT efficiently.

• Writing to reload register R1

When writing data to reload register R1 while timer 1 is
operating, avoid a timing when timer 1 underflows.

• Timer 1 count operation

When the bit 5 of the watchdog timer (WDT) is selected as
the timer 1 count source, the error of maximum ± 256 µs
(at the minimum instruction execution time : 8 µs) is
generated from timer 1 start until timer 1 underflow. When
programming, be careful about this error.

• Stop of timer 2

Avoid a timing when timer 2 underflows to stop timer 2.

• Writing to reload register R2H

When writing data to reload register R2H while timer 2 is
operating, avoid a timing when timer underflows.

• Timer 2 carrier wave output function

When to expand “H” interval of carrier wave is valid, set “1”
or more to reload register R2H.

12

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SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

(3) Timer 1

Timer 1 is an 8-bit binary down counter with the timer 1 reload
register (R1).
When timer is stopped, data can be set simultaneously in timer
1 and the reload register (R1) with the T1AB instruction.
When timer is operating, data can be set to only reload register
R1 with the T1AB instruction.
When setting the next count data to reload register R1 at
operating, set data before timer 1 underflows.
Timer 1 starts counting after the following process;

➀ set data in timer 1,
➁ select the count source with the bit 1 of register V1, and
➂ set the bit 0 of register V1 to “1.”

Once count is started, when timer 1 underflows (the next count
pulse is input after the contents of timer 1 becomes “0”), the
timer 1 underflow flag (T1F) is set to “1,” new data is loaded
from reload register R1, and count continues (auto-reload
function).
When a value set in reload register R1 is n, timer 1 divides the
count source signal by n + 1 (n = 0 to 255).
When the bit 2 of register V1 is set to “1,” the carrier wave
output enable/disable interval of port CARR is alternately
generated each timer 1 underflows (Figure 14).
Data can be read from timer 1 to registers A and B. When
reading the data, stop the counter and then execute the TAB1
instruction.

(4) Timer 2

Timer 2 is an 8-bit binary down counter with the timer 2 reload
registers (R2H and R2L).
Data can be set simultaneously in timer 2 and the reload
register (R2L) with the T2AB instruction.
The contents of reload register (R2L) set with the T2AB
instruction can be set again to timer 2 with the T2R2L
instruction. Data can be set to reload register (R2H) with the
T2HAB instruction.
Timer 2 starts counting after the following process;

➀ set data in timer 2,
➁ select the count source with the bit 1 of register V2, and
➂ select the valid/invalid of the carrier wave generation

function by bit 2 of register V1 (when this function is valid,
select the valid/invalid of the carrier wave “H” interval

expansion by bit 3), and
➃ set the bit 0 of register V1 to “1.”
When the carrier wave generation function is invalid (V2
the following operation is performed;
Once count is started, when timer 2 underflows (the next count
pulse is input after the contents of timer 2 becomes “0”), the
timer 2 underflow flag (T2F) is set to “1,” new data is loaded
from reload register R2L, and count continues (auto-reload
function).
When a value set in reload register R2L is n, timer 2 divides
the count source signal by n + 1 (n = 0 to 255).
When the carrier wave generation function is valid (V2
the carrier wave which has the “L” interval set to the reload
register R2L and “H” interval set to the reload register R2H
can be output (Figure 15).
After the count of the “L” interval of carrier wave is started,
timer 2 underflows and the timer 2 underflow flag (T2F) is set

2=“0”),

2=“1”),

to “1”. Then, the “H” interval data of carrier wave is reloaded
from the reload register R2H, and count continues.
When timer underflows again after auto-reload, the T2F flag
is set to “1”. And then, the “L” interval data of carrier wave is
reloaded from the reload register R2L, and count continues.
After that, each timer underflows, data is reloaded from reload
register R2H and R2L alternately.
When a value set in reload register R2H is n, “H” interval of
carrier wave is as follows;
➀ When to expand “H” interval is invalid (V2

Count source ✕ (n+1), n = 0 to 255

➁ When to expand “H” interval is valid (V2

Count source ✕ (n+1.5), n = 1 to 255
When a value set in reload register R2L is m, “L” interval of
carrier wave is as follows;

Count source ✕ (m+1), m = 0 to 255
Data can be read from timer 2 to registers A and B. When
reading the data, stop the counter and then execute the TAB2
instruction.

(5) Timer underflow flags (T1F, T2F)

Timer 1 underflow flag or timer 2 underflow flag is set to “1”
when the timer 1 or timer 2 underflows. The state of flags T1F
and T2F can be examined with the skip instruction (SNZT1,
SNZT2).
Flags T1F and T2F are cleared to “0” when the next instruction
is skipped with a skip instruction.

3 = “0”),

3 = “1”),

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13

T i m e r 1 u n d e r f l o w

Port CARR output

S e t t h e i n t e r v a l “ a ” t o t i m e r 1 .

C o u n t s o u r c e C A R R Y s e l e c t e d

T i m e r 1 u n d e r f l o w

C A R R Y

Port CARR output

R e g i s t e r V 1

T i m e r 1 s t a r t s

“1”
“0”

“ H ”

“L”

▲▲ ▲ ▲

( V 11)←0

A u t o - c o n t r o l v a l i d

( V 12)←1

“ 1 ”
“ 0 ”

“H”

“ L ”

“H”

“ L ”
“ 1 ”

2

“ 0 ”

C a r r i e r w a v e o u t p u t s t a r t

(V10)←1

a b c

S e t t h e i n t e r v a l “ b ”
t o r e l o a d r e g i s t e r R 1 .

Carrier wave output start

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Set the interval “c”
to reload register R1.

A u t o - c o n t r o l i n v a l i dAuto-control invalid

MITSUBISHI MICROCOMPUTERS

4282 Group

d

Set the interval “d”
to reload register R1.

T i m e r 1 s t o p

( V 10)←0

( N o t e )

Carrier wave output stop

N o t e : W h e n t i m e r 1 i s s t o p p e d , t h e p o r t C A R R o u t p u t a u t o - c o n t r o l i s t e r m i n a t e d r e g a r d l e s s o f b i t 2 ( V 12) o f r e g i s t e r V 1 .

Fig. 14 Port CARR output control by timer 1

● I n t h i s c a s e , t h e f o l l o w i n g i s s e t ;

• T i m e r 2 c a r r i e r w a v e g e n e r a t i o n f u n c t i o n i s v a l i d ( V 2

• “ L ” i n t e r v a l ( 0 3

• “ H ” i n t e r v a l ( 0 2

T o e x p a n d “ H ” i n t e r v a l o f c a r r i e r w a v e i s i n v a l i d ( V 23= “ 0 ” )
[ C o u n t s o u r c e : 4 . 0 M H z , R e s o l u t i o n : 2 5 0 n s ]

T i m e r 2 c o u n t s o u r c e

T i m e r 2 c o u n t v a l u e
(Reload register)

T i m e r 2 u n d e r f l o w s i g n a l

T o e x p a n d “ H ” i n t e r v a l o f c a r r i e r w a v e i s v a l i d ( V 23= “ 1 ” )
(W h e n c o u n t s o u r c e i s 4 . 0 M H z , c a r r i e r w a v e i s e x p a n d e d f o r 1 2 5 n s ]

T i m e r 2 c o u n t s o u r c e

T i m e r 2 c o u n t v a l u e
( R e l o a d r e g i s t e r )

T i m e r 2 u n d e r f l o w s i g n a l

C A R R Y D

1 6

) o f c a r r i e r w a v e i s s e t t o r e l o a d r e g i s t e r R 2 L

1 6

) o f c a r r i e r w a v e i s s e t t o r e l o a d r e g i s t e r R 2 H

0 2

1 6

0 1

0 3

1 6

(R2L)

T i m e r 2 s t a r t s

0 3

1 6

(R2L)

1 6

0 2

1 6

0 1

1 60016

2

= “ 1 ” ) ,

0 2

1 60116

0 0

03

0 0

1 6

0 2

1 6

0 1

1 6

( R 2 H ) (R2L) (R2H) (R2L) ( R 2 H )

3 c l o c k s

i n t e r v a l

C a r r i e r w a v e p e r i o d :

0 2

1 6

0 1

( R 2 H )

16

0 0

1 6

7 c l o c k s

02160 1

0 3

1 6

1 6

0 0

1 6

( R 2 L ) (R2H) ( R 2 L ) ( R 2 H )

1 6

1 60016

021601160 0

3 clocks

interval

C a r r i e r w a v e p e r i o d :

02160 1

03

1 6

7 c l o c k s

1 6

0 0

16

1 6

02160 1

03

16

1 6

0 2

1 6

0 0

1 6

02160 1

1 6

0 1

1 6

0 0

1 6

0 2

1 6

C A R R Y D

T i m e r 2 s t a r t s

N o t e : W h e n t o e x p a n d “ H ” i n t e r v a l o f t h e c a r r i e r w a v e i s v a l i d , s e t “ 0 1

Fig. 15 Carrier wave generation example by timer 2

14

3 . 5 c l o c k s

i n t e r v a l

C a r r i e r w a v e p e r i o d :

7 . 5 c l o c k s

1 6

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ELECTRIC

3 . 5 c l o c k s

i n t e r v a l

C a r r i e r w a v e p e r i o d :

” o r m o r e t o r e l o a d r e g i s t e r R 2 H .

7 . 5 c l o c k s

● In this case, the following is set;

• To expand “H” interval of carrier wave is invalid (V2

• Timer 2 carrier wave generation function is valid (V2

• Count source X

• “L” interval (03

• “H” interval (02

IN

/2 selected (V21=“1”),

16

) of carrier wave is set to reload register R2L

16

) of carrier wave is set to reload register R2H

Timer 2 count start timing

3

= “0”),

2

=“1”),

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Machine cycle

Instruction clock

(Count source selected)

Timer 2 count value

(Reload register)

Timer 2 underflow signal

IN

=f(X

XIN/2

Register V2

CARRYD

Timer 2 count stop timing

Machine cycle

Instruction clock

=f(X

(Count source selected)

Timer 2 count value
(Reload register)

Timer 2 underflow signal

XIN/2

Register V2

Mi Mi + 1 Mi + 2

TV2A instruction execution cycle (V20) ←1

)/8

X

IN

0

03

(R2L)

16

0216011600

0216011600

16

(R2H) (R2L)

Timer 2 count start timing

Mi Mi + 1 Mi + 2

TV2A instruction execution cycle (V20)←0

IN

)/8

X

IN

0

02

00

02160116001602160116001603

16

03

16

(R2H)(R2L)

0216011600

16

16

16

(R2H)(R2L)

16

02

16

03

16

CARRYD

Notes 1: When the carrier wave generation function is vaild (V2

when timer 2 underflows to stop timer 2. When the timer 2 count stop occurs
at the same timing with the timer 2 underflows, hazard may occur in the carrier
wave output waveform.

2: When the timer 2 is stopped during “H” output of carrier wave while the carrier

wave generation function is valid, it is stopped after the “H” interval set by
reload register R2H is output.

Fig. 16 Timer 2 count start/stop timing

Timer 2 count stop timing

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(Note 1)

2

=“1”), avoid a timing

15

WATCHDOG TIMER

S

Sof

S

Watchdog timer provides a method to reset and restart the system
when a program runs wild. Watchdog timer consists of 14-bit
timer (WDT) and watchdog timer flags (WDF1, WDF2).
Watchdog timer downcounts the instruction clock (INSTCK) as
the count source immediately after system is released from reset.
When the timer WDT count value becomes 0000
occurs, the WDF1 flag is set to “1.” Then, when the WRST
instruction is not executed before the timer WDT counts 16383,
WDF2 flag is set to “1” and internal reset signal is generated and
system reset is performed.
Execute the WRST instruction at period of 16383 machine cycle
or less to keep the microcomputer operation normal.
Timer WDT is also used for generation of oscillation stabilization
time. When system is returned from reset and from RAM back­up mode by key-input, software starts after the stabilization
oscillation time until timer WDT downcounts to 3E00

16 and underflow

16 elapses.

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3 F F F

3 E 0 0

1 6
1 6

o f t w a r e s t a r

t

tware start

Value of timer WDT

0 0 0 0

1 6

W D F 1 f l a g

WDF2 flag

“1”

“ 0 ”

“ 1 ”

“0”

I n t e r n a l r e s e t s i g n a l

“H”

“L”

POF

instruction

execution

S y s t e m

Return

r e s e t

Fig. 17 Watchdog timer function

LOGIC OPERATION FUNCTION

The 4282 Group has the 4-bit logic operation function. The logic
operation between the contents of register A and the low-order
4 bits of register E is performed and its result is stored in register
A.

Table 5 Logic operation selection register LO

WRST

instruction

o f t w a r e s t a r

S y s t e m
r e s e t

t

execution

Each logic operation can be selected by setting logic operation
selection register LO.
Set the contents of this register through register A with the TLOA
instruction. The logic operation selected by register LO is
executed with the LGOP instruction.
Table 5 shows the logic operation selection register LO.

Logic operation selection register LO

LO1

Logic operation selection bits

LO0

Note: “W” represents write enabled.

16

at reset : 002

LO1

0

LO

0

0

0

1

1

0

1

1

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at RAM back-up : 002

Logic operation function
Exclusive logic OR operation (XOR)
OR operation (OR)
AND operation (AND)
Not available

W

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SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

RESET FUNCTION

The 4282 Group has the power-on reset circuit, though it does
not have RESET pin. System reset is performed automatically
at power-on, and software starts program from address 0 in page

0.

f(XIN)

Internal reset signal

Fig. 18 Reset release timing

“H”
“L”

f(XIN) 16384 pulses

Internal reset signal

In order to make the built-in power-on reset circuit operate
efficiently, set the voltage rising time until V
obtained at power-on 1ms or less.

Software operation starts
(address 0 in page 0)

V

DD

Power-on reset circuit
output voltage

DD= 0 to 2.2 V is

Fig. 19 Power-on reset circuit example

Power-on reset circuit

Voltage drop detection circuit

Watchdog timer output

Reset state

Internal reset signal

Reset released

Power-on

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17

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SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

(1) Internal state at reset

Table 6 shows port state at reset, and Figure 20 shows internal
state at reset (they are retained after system is released from
reset).

• Program counter (PC) ..............................................................

Address 0 in page 0 is set to program counter.

• Power down flag (P).................................................................

• Timer 1 underflow flag (T1F) ...................................................

• Timer 2 underflow flag (T2F) ...................................................

• Timer control register V1..........................................................

• Timer control register V2..........................................................

• Port CARR output flag (CAR) ..................................................

• Pull-down control register PU0 ................................................

• Pull-down control register PU1 ................................................

• Logic operation selection register LO ......................................

• Most significant ROM code reference enable flag (URS)

• Carry flag (CY) .........................................................................

• Register A.................................................................................

• Register B.................................................................................

• Register X.................................................................................

• Register Y.................................................................................

• Stack pointer (SP) ....................................................................

The contents of timers, registers, flags and RAM except shown
in Figure 20 are undefined, so set the initial value to them.

00000000000

0
0
0
000
0000
0
0000
0000
00
0
0
1111
1111
00
0000
11

Fig. 20 Internal state at reset
Table 6 Port state at reset

Name

High impedance state

0–D3

D
D4–D7
G0–G3
E0, E1
CARR

Note: The contents of all output latch is initialized to “0.”

High impedance state (Pull-down transistor OFF)
High impedance state (Pull-down transistor OFF)
High impedance state (Pull-down transistor OFF)
“L” output

State at reset

VOLTAGE DROP DETECTION CIRCUIT

The built-in voltage drop detection circuit is designed to detect a
drop in voltage at operating and to reset the microcomputer if
the supply voltage drops below the specified value (Typ. 1.50 V)
or less.

VDD

Reset voltage

TYP 1.5V

Internal reset signal

The voltage drop detection circuit is stopped and power
dissipation is reduced in the RAM back-up mode with the
initialized CPU stopped.

(Note)

Microcomputer starts operation
after f(X

IN

) is counted to 16384 times.

Note: The voltage drop detection circuit does not have

the hysteresis characteristics in the detected voltage.

Fig. 21 Voltage drop detection circuit operation waveform

18

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SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

RAM BACK-UP MODE

The 4282 Group has the RAM back-up mode.
When the POF instruction is executed, system enters the RAM
back-up state.
As oscillation stops retaining RAM, the functions and states of
reset circuit at RAM back-up mode, power dissipation can be
reduced without losing the contents of RAM. Table 7 shows the
function and states retained at RAM back-up. Figure 22 shows
the state transition.

(1) Warm start condition

When the external wakeup signal is input after the system
enters the RAM back-up state by executing the POF
instruction, the CPU starts executing the software from address
0 in page 0. In this case, the P flag is “1.”

(2) Cold start condition

The CPU starts executing the software from address 0 in page
0 when any of the following conditions is satisfied .

• reset by power-on reset circuit is performed

• reset by watchdog timer is performed

• reset by voltage drop detection circuit is performed
In this case, the P flag is “0.”

(3) Identification of the start condition

Warm start (return from the RAM back-up state) or cold start
(return from the normal reset state) can be identified by
examining the state of the power down flag (P) with the SNZP
instruction.

Table 7 Functions and states retained at RAM back-up

Function
Program counter (PC), registers A, B,
carry flag (CY), stack pointer (SP) (Note 2)
Contents of RAM
Port CARR

0–D7

Ports D
Ports E0, E1
Port G
Timer control registers V1, V2
Pull-down control registers PU0, PU1
Logic operation selection register LO
Timer 1 function, Timer 2 function
Timer underflow flags (T1F, T2F)
Watchdog timer (WDT)
Watchdog timer flags (WDF1, WDF2)
Most significant ROM code reference enable flag (URS)

Notes 1: “O” represents that the function can be retained, and

“✕” represents that the function is initialized.
Registers and flags other than the above are undefined
at RAM back-up, and set an initial value after returning.

2:The stack pointer (SP) points the level of the stack

register and is initialized to “11

RAM back-up

✕

O

✕

O
O
O

✕

O

✕
✕
✕
✕
✕
✕

2” at RAM back-up.

Reset

(Stabilizing time a )

Stabilizing time a

Fig. 22 State transition

: Microcomputer starts its operation after f(XIN) is counted to16384 times.

Power down flag P

POF instruction

SRQ

Reset input

● Set source POF instruction is executed

● Clear source Reset input

Fig. 23 Set source and clear source of the P flag

A

f(XIN) oscillation

POF instruction

B

is executed

IN

) stop

f(X

Return input

(Stabilizing time a )

(RAM back-up
mode)

Software start

P = “1”

?

Yes

No

Cold start

Fig. 24 Start condition identified example using the SNZP

instruction

Warm start

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19

(4) Return signal

An external wakeup signal is used to return from the RAM
back-up mode. Table 8 shows the return condition for each
return source.

Table 8 Return source and return condition

Return source

4–D7

Ports D

Return by an external “H” level

Return condition

input.

Ports E0, E1, G

Return by an external “H” level
input.

2

Ports E

Return by an external “H” level
input.

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SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

Remarks
Only key-on wakeup function of the port whose pull-down transistor is
turned ON by register PU1 is valid.
Only key-on wakeup function of the port whose pull-down transistor is
turned ON by register PU0 is valid.
Key-on wakeup function is always valid.

(5) Pull-down control register

Registers PU0 and PU1 are 4-bit registers and control the
ON/OFF of pull-down transistor and key-on wakeup function
for ports E

0, E1, G and ports D4–D7.

Table 9 Pull-down control registers

Pull-down control register PU0

2, G3 pull-down transistor control

PU03

PU02

PU01

PU00

Ports G
bit

0, G1 pull-down transistor control

Ports G
bit

1 pull-down transistor control bit

Port E

0 pull-down transistor control bit

Port E

Pull-down control register PU1

PU13

PU12

PU11

PU10

7 pull-down transistor control bit

Port D

6 pull-down transistor control bit

Port D

5 pull-down transistor control bit

Port D

4 pull-down transistor control bit

Port D

Note: “W” represents write enabled.

Set the contents of register PU0 or PU1 through register A
with the TPU0A or TPU1A instruction, respectively.

at reset : 0000

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

at reset : 0000

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

Pull-down transistor OFF, key-on wakeup invalid

0

Pull-down transistor ON, key-on wakeup valid

1

2 at RAM back-up : state retained W

2 at RAM back-up : state retained W

20

MITSUBISHI
ELECTRIC

CLOCK CONTROL

The clock control circuit consists of the following circuits.

• System clock generating circuit

• Control circuit to stop the clock oscillation

• Control circuit to return from the RAM back-up state

MITSUBISHI MICROCOMPUTERS

4282 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

C C K i n s t r u c t i o n

X

I N

X

OUT

POF instruction

Fig. 25 Clock control circuit structure

System clock signal f(X
ceramic resonator. Connect this external circuit to pins X
X

OUT at the shortest distance as shown Figure 26.

A feedback resistor is built-in between X

IN) is obtained by externally connecting a

O S C

R

Q

S

F r e q u e n c y
d i v i d e r
( d i v i d e d b y 8 )

IN and

IN pin and XOUT pin.

ROM ORDERING METHOD

Please submit the information described below when ordering
Mask ROM.
(1) Mask ROM Order Confirmation Form
(2) Mark Specification Form
(3) Data to be written to ROM, in EPROM form (three identical

copies) or one floppy disk.

*

M u l t i ­p l e x e r

I n t e r n a l c l o c k
g e n e r a t i o n c i r c u i t
( d i v i d e d b y 4 )

STCK

I n t e r n a l p o w e r - o n r e s e t c i r c u i t

P u l l - d o w n c o n t r o l
r e g i s t e r P U 0

Pull-down control
register 1

4282

X

IN

45

C

IN

X

P o r t s E0, E1, G0– G

Ports D4–D

P o r t E

OUT

C

OUT

INSTCK

3

7

2

Use the resonator
manufacturer’s
recommended value
because constants
such as capacitance
depend on the
resonator.

* For the mask ROM confirmation, refer to the “Mitsubishi MCU

Technical Information” Homepage (http://
www.infomicom.maec.co.jp/indexe.htm).

MITSUBISHI
ELECTRIC

Fig. 26 Ceramic resonator external circuit

21