CHAPTER 18 IEBus CONTROLLER (V850/SC2)
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User’s Manual U15109EJ3V0UD
(8) IEBus unit status register (USR)
After reset: 00H
R
Address: FFFFF3EEH
7
<6>
<5>
<4>
<3>
<2>
1
0
USR
0
SLVRQ
ARBIT
ALLTRNS
ACK
LOCK
0
0
SLVRQ
Slave request flag
0
No request from master to slave
1
Request from master to slave
ARBIT
Arbitration result flag
0
Arbitration win
1
Arbitration loss
ALLTRNS
Broadcast communication flag
0
Individual communication status
1
Broadcast communication status
ACK
ACK transmission flag
0
NACK transmitted
1
ACK transmitted
LOCK
Lock status flag
0
Unit unlocked
1
Unit locked
(a) Slave request flag (SLVRQ)...Bit 6
This flag indicates whether there was a slave request from the master.
<Set/reset conditions>
Set: When the IEBus unit has been sent a slave request (during individual communication
reception, when the received slave address and local UAR match; during broadcast reception,
when the higher 4 bits of the received slave address match, or the received slave address is
FFFH), the flag is set by hardware at the start of the acknowledge period for the slave address
field.
Reset: When the IEBUS unit is not sent a slave request, the flag is reset by hardware. The timing is
the same as for Set. However, if immediately following normal reception of a communication
(SLVRQ bit is set), the IEBus unit is sent a slave request and a parity error occurs in the slave
address field for that communication, the flag is not reset.