NEC PD75402A - Manual (Page 134)

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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
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STATUS command
This command is used to read the status of the currently selected slave.
Fig. 5-57 STATUS Command Transfer Format
M S
STATUS ACK
Command
S S
Status ACK
Data
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
Status 7 6 5 4 3 2 1 0
MSB LSB
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.
All 0s