NEC PD750008 - Manual (Page 197)

177
CHAPTER 5 PERIPHERAL HARDWARE FUNCTIONS
<3> STATUS command
The STATUS command reads the status of the current slave.
Figure 5-75. Transfer Format of the STATUS Command
Remark M: Output by the master
S: Output by the slave
The slave returns the status in the format shown in Figure 5-78.
Figure 5-76. Status Format of the STATUS Command
When the master receives a status, it returns ACK to the current slave.
STATUS
M
ACK
S
Data
Status
S
ACK
S
Command
7 6 5 4 3 2 1 0 Status
MSB LSB
All 0s
Bit indicating whether there is data ready for transmission
0 : No transmit data
1 : Transmit data of one byte or more
Bit indicating whether the device is ready for data reception
0 : No receive data storage area
1 : Receive data storage area not smaller than one byte is present.
Bit indicating whether an error occurred
0 : No error
1 : Error occurred during previous transfer.
Bit indicating whether master can be changed or not
0 : Master cannot be changed.
1 : Master can be changed.