CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
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If the control bit received from the master unit is not as shown in Table 19-3, the unit locked by the master
unit rejects acknowledging the control bit, and does not output the acknowledge bit.
Table 19-3. Control Field for Locked Slave Unit
Bit 3
Note
1
Bit 2
Bit 1
Bit 0
Function
0
0
0
0
Reads slave status
0
1
0
0
Reads lock address (lower 8 bits)
0
0
0
1
Reads lock address (higher 4 bits)
Moreover, units for which lock is not set by the master unit reject acknowledgement and do not output an
acknowledge bit when the control data shown in Table 19-4 is acknowledged.
Table 19-4. Control Field for Unlocked Slave Unit
Bit 3
Bit 2
Bit 1
Bit 0
Function
0
1
0
0
Lock address read (lower 8 bits)
0
1
0
1
Lock address read (higher 4 bits)
If one unit occupies the bus as the master, the value set to the IEBus control register (CDR) is output.
Figure 19-4. Control Field
MSB
LSB
ACK
Parity
Control bit (4 bits)
Control field
