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¡ Semiconductor

MSM82C51A-2RS/GS/JS

Control Words

There are two types of control word.

1. Mode instruction (setting of function)

2. Command (setting of operation)

1) Mode Instruction

Mode instruction is used for setting the function of the MSM82C51A-2. Mode instruction

will be in “wait for write” at either internal reset or external reset. That is, the writing of a

control word after resetting will be recognized as a “mode instruction.”

Items set by mode instruction are as follows:

•

Synchronous/asynchronous mode

•

Stop bit length (asynchronous mode)

•

Character length

•

Parity bit

•

Baud rate factor (asynchronous mode)

•

Internal/external synchronization (synchronous mode)

•

Number of synchronous characters (Synchronous mode)

The bit configuration of mode instruction is shown in Figures 2 and 3. In the case of

synchronous mode, it is necessary to write one-or two byte sync characters.

If sync characters were written, a function will be set because the writing of sync characters

constitutes part of mode instruction.

EP

PEN

0

1

0

1

0

0

1

1

Refer to

Fig. 3

SYNC

1 ¥

16 ¥

64 ¥

Baud Rate Factor

0

1

0

0

0

1

5 bits

6 bits

7 bits

Charactor Length

1

1

8 bits

0

1

0

1

0

0

1

1

Disable

Odd

Parity

Disable

Even

Parity

Parity Check

0

1

0

0

0

1

Inhabit

1 bit

1.5 bits

Stop bit Length

1

1

2 bits

Fig. 2 Bit Configuration of Mode Instruction (Asynchronous)