MSM82C55A-2VJS View Datasheet(PDF) - Oki Electric Industry

Part Name

Description

MFG CO.

MSM82C55A-2VJS

CMOS programmable peripheral interface

Oki Electric Industry 

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¡ Semiconductor

MSM82C55A-2RS/GS/VJS

4. When Group A is Different in Mode from Group B

Group A and group B can be used by setting them in different modes each other at the same

time. When either group is set to mode 1 or mode 2, it is possible to set the one not defined

as a control pin in port C to both input and output as port which operates in mode 0 at the

3rd and 0th bits of the control word.

(Mode combinations that define no control bit at port C)

Port C

Group A Group B

PC7 PC6

PC5

PC4

PC3

PC2

PC1

PC0

1

Mode 1

input

Mode 0

I/O

I/O

IBFA

STBA INTRA

I/O

I/O

I/O

2

Mode 0

Output

Mode 0

OBFA

ACKA

I/O

3 Mode 0

Mode 1

Input

I/O

I/O

I/O

I/O

INTRA

I/O

I/O

I/O

I/O

I/O

STBB

IBFB INTRB

4 Mode 0 Mode 1

I/O

Output

I/O

I/O

I/O

I/O

ACKB OBFB INTRB

5 Mode 1 Mode 1

I/O

Input

Input

I/O

IBFA

STBA INTRA STBB

IBFB INTRB

6 Mode 1 Mode 1

I/O

I/O

Input

Output

7

Mode 1

Output

Mode 1

Input

OBFA

ACKA

IBFA

STBA INTRA ACKB

OBFB INTRB

I/O

I/O

INTRA STBB

IBFB INTRB

8

Mode 1

Output

Mode 1

Output

OBFA

ACKA

I/O

I/O

INTRA ACKB OBFB INTRB

9 Mode 2 Mode 0 OBFA ACKA

IBFA

STBA INTRA

I/O

I/O

I/O

Controlled at the 3rd bit (D3) of

the Control Word

Controlled at the 0th bit (D0) of

the Control Word

When the I/O bit is set to input in this case, it is possible to access data by the normal port

C read operation.

When set to output, PC7-PC4 bits can be accessed by the bit set/reset function only.

Meanwhile, 3 bits from PC2 to PC0 can be accessed by normal write operation.

The bit set/reset function can be used for all of PC3-PC0 bits. Note that the status of port C

varies according to the combination of modes like this.

19/26

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