NEC PD75P402, PD75402A user manual ➂ Status command, 123, Msb Lsb

Models: PD75402A PD75P402

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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS

STATUS command

This command is used to read the status of the currently selected slave.

Fig. 5-57 STATUS Command Transfer Format

M

STATUS

Command

S

ACK

S

Status

Data

S

ACK

Remarks M : Output by master

S : Output by slave

The format of the status byte returned by the slave is shown below.

Fig. 5-58 STATUS Command Status Format

MSB

 

 

 

 

 

 

LSB

Status

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

All 0s

Bit indicating possibility of data transmission

0: No data for transmission

1: 1 or more bytes of send data ready Bit indicating possibility of data reception

0: No receive data storage area

1: 1 or more bytes of receive data storage area ready Bit indicating error occurrence

0: No error

1: Error occurred in previous transfer Bit indicatin possibility of change of master

0: Chang of master not possible

1: Change of mster possible

When the slave sends status data, it compares the SIO contents before and after transmission and if they do not match an error is generated and no ACK is returned.

123

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NEC PD75P402, PD75402A user manual ➂ Status command, 123, Msb Lsb