NEC Renesas V850/SC1 User Manual page 514

(5) Control field
The master outputs the operation it requires the slave to perform, by using this field.
The configuration of the control field is as shown in Figure 18-4.
If the parity following the control bit is even and if the slave unit can execute the function required by the
master unit, the slave unit outputs an acknowledge signal and starts outputting the telegraph length field. If the
slave unit cannot execute the function required by the master unit even if the parity is even, or if the parity is
odd, the slave unit does not output the acknowledge signal, and returns to the standby (monitor) status.
The master unit starts outputting the telegraph length field after confirming the acknowledge signal.
If the master cannot confirm the acknowledge signal, the master unit enters the standby status, and
communication ends.
acknowledge signal, and starts outputting the telegraph length field.
Table 18-2 shows the contents of the control bits.
Note 1
Bit 3 Bit 2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Notes 1. The telegraph length bit of the telegraph length field and data transfer direction of the data field
change as follows depending on the value of bit 3 (MSB).
If bit 3 is '1': Transfer from master unit to slave unit
If bit 3 is '0': Transfer from slave unit to master unit
2. This is a control bit that specifies locking or unlocking (refer to 18.1.7 (4) Locking and unlocking).
3. The lock address is transferred in 1-byte (8-bit) units and is configured as follows:
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CHAPTER 18 IEBus CONTROLLER (V850/SC2)
During broadcast communication, however, the master unit does not confirm the
Table 18-2. Contents of Control Bits
Bit 1 Bit 0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
MSB
Control bit: 4H
Control bit: 5H Undefined
User's Manual U15109EJ3V0UD
Function
Reads slave status
Undefined
Undefined
Note 2
Reads data and locks
Reads lock address (lower 8 bits)
Reads lock address (higher 4 bits)
Reads slave status and unlocks
Reads data
Undefined
Undefined
Note 2
Writes command and locks
Note 2
Writes data and locks
Undefined
Undefined
Writes command
Writes data
Lower 8 bits
Higher 4 bits
Note 3
Note 3
Note 2
LSB