CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
461
Figure 19-15. IEBus Control Data Register (CDR) Format
After reset: 01H
R/W
Address: FFFFF3E8H
7
6
5
4
3
2
1
0
CDR
0
0
0
0
MOD
SELCL2
SELCL1
SELCL0
MOD
SELCL2
SELCL1
SELCL0
Function
0
0
0
0
Reads slave status
0
0
0
1
Undefined
0
0
1
0
Undefined
0
0
1
1
Reads data and locks
0
1
0
0
Reads lock address (lower 8 bits)
0
1
0
1
Reads lock address (lower 4 bits)
0
1
1
0
Reads slave status and unlocks
0
1
1
1
Reads data
1
0
0
0
Undefined
1
0
0
1
Undefined
1
0
1
0
Writes command and locks
1
0
1
1
Writes data and locks
1
1
0
0
Undefined
1
1
0
1
Undefined
1
1
1
0
Writes command
1
1
1
1
Writes data
Cautions 1. Because the slave unit must judge whether the received data is a “command” or “data”, it
must read the value of this register after completing communication.
2. If the master unit sets an undefined value, NACK is returned from the slave unit, and
communication is aborted. During broadcasting communication, however, the master unit
continues communication without recognizing ACK/NACK; therefore, make sure not to set
an undefined value to this register during broadcasting communication.
3. In the case of defeat in a bus conflict and a slave status request is received from the unit
that won, the telegraph length register (DLR) is fixed to “01H”. Therefore, when a re-request
of the master follows, the appointed telegraph length must be set to DLR.
