CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
468
(b) Arbitration result flag (ARBIT)...Bit 5
A flag that indicates the result of arbitration.
<Set/reset conditions>
Set:
When the data output by the IEBus unit during the arbitration period does not match the bus
line data.
Reset: By the start bit timing.
Cautions 1. The timing at which the arbitration result flag (ARBIT) is reset differs depending on
whether the unit outputs a start bit.
•
If start bit is output: The flag is reset at the output start timing.
•
If start bit is not output: The flag is reset at the detection timing of the start bit (approx.
160
µ
s after output)
2. The flag is reset at the detection timing of the start bit if the other unit outputs the
start bit earlier and the unit does not output the start bit after the master request.
(c) Broadcasting communication flag (ALLTRNS)...Bit 4
A flag indicating whether the unit is performing broadcasting communication. The contents of the flag are
updated in the broadcast field of each frame.
Except for initialization (reset) by system reset, the set/reset conditions vary depending on the receive
data of the broadcast field bit.
<Set/reset conditions>
Set:
When “broadcasting” is received by the broadcast field
Reset: When “individual” is received by the broadcast field, or upon the input of a system reset.
Caution The broadcast flag is updated regardless of whether IEBus is the communication target or
not.
Figure 19-23. Example of Broadcasting Communication Flag Operation
Broadcasting
communication flag
Reset
Set
Not reset
by start bit
IEBus sequence
Start
M11
Broad-
casting
M10
M11
Individual
M10
Start
(d) ACK transmission flag (ACK)...Bit 3
A flag that indicates whether ACK has been transmitted in the ACK period of the ACK field when the
IEBus is a receiving unit. The contents of the flag are updated in the ACK period of each frame.
However, if the internal circuit is initialized by the occurrence of a parity error, etc., the contents are not
updated in the ACK period of that field.
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