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NEC PD75402A User Manual

Page 89

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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS

(2)

Serial bus interface control register (SBIC)

The format of the serial bus interface control register (SBIC) is shown in Fig. 5-26.

SBIC is an 8-bit register composed of bits which control the serial bus and flags which indicate various statuses

of the input data from the serial bus, and is mainly used in the SBI mode.

SBIC is manipulated by bit-manipulation instructions; it cannot be manipulated by 4-bit or 8-bit memory

manipulation instructions.

Read/write capability differs from bit to bit (see Fig. 5-26).

Reset input clears this register to 00H.

Note

In the 3-wire serial I/O mode, only the following bits can be used:

• Bus release trigger bit (RELT) … SO latch setting

• Command trigger bit (CMDT) … SO latch clearing

Fig. 5-26 Serial Bus Interface Control Register (SBIC) Format (1/3)

Address

7

6

5

4

3

2

1

0

Symbol

FE2H

BSYE

ACKD

ACKE

ACKT

CMDD

RELD

CMDT

RELT

SBIC

Bus Release Trigger Bit (W)

Command Trigger Bit (W)

Bus Release Datection Flag (R)

Command Detection Flag (R)

Acknowledge Trigger Bit (W)

Acknowledge Enable Bit (R/W)

Acknowledge Detection Flag (R)

Busy Enable Bit (R/W)

Remarks

(R)

Read only

(W)

Write only

(R/W) Read/write enabled

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