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CHAPTER 18 IEBus CONTROLLER (V850/SC2)
User’s Manual U15109EJ3V0UD
521
(c) Lock setting conditions
Broadcast Communication
Individual Communication
Control Data
Communication End
Frame End
Communication End
Frame End
3H, 6H
Note
Cannot be locked
Lock set
AH, BH
Cannot be locked
Cannot be locked
Cannot be locked
Lock set
0H, 4H, 5H, EH, FH
Cannot be locked
Cannot be locked
Cannot be locked
Cannot be locked
(d) Lock release conditions (while locked)
Broadcast Communication from
Lock Request Unit
Individual Communication from
Lock Request Unit
Control Data
Communication End
Frame End
Communication End
Frame End
3H, 6H
Note
Unlocked
Remains locked
AH, BH
Unlocked
Unlocked
Unlocked
Remains locked
0H, 4H, 5H, EH, FH
Remains locked
Remains locked
Remains locked
Remains locked
Note
The frame end of control data 6H (slave status read/unlock) occurs when the parity in the data field
is odd, and when the acknowledge signal from the IEBus unit is repeated up to the maximum
number of transfer bytes without being output.
18.1.8 Bit format
The format of the bits constituting the communication frame of the IEBus is shown below.
Figure 18-9. Bit Format of IEBus
Logic “1”
Logic “0”
Preparation
period
Synchronization
period
Data period
Stop period
Preparation period:
First low-level (logic “1”) period
Synchronization period: Next high-level (logic “0”) period
Data period:
Period indicating value of bit
Stop period:
Last low-level (logic “1”) period
The synchronization period and data period are almost equal to each other in length.
The IEBus synchronizes each bit. The specifications on the time of the entire bit and the time related to the period
allocated to that bit differ depending on the type of the transmit bit, or whether the unit is the master unit or a slave
unit. During communication, the master and slave units detect whether each period (preparation period,
synchronization period, data period, and stop period) is output for the specified time. If not, the master and slave units
regard it as a timing error, and immediately stop communication and return to the wait status.