User’s Manual U13850EJ4V0UM
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CHAPTER 19 IEBus CONTROLLER (V850/SB2)
IEBus (Inter Equipment Bus) is a small-scale digital data transfer system that transfers data between units. To
implement IEBus with the V850/SB2, an external IEBus driver and receiver are necessary because they are not
provided.
The internal IEBus controller of the V850/SB2 is of negative logic.
19.1 IEBus Controller Function
19.1.1 Communication protocol of IEBus
The communication protocol of the IEBus is as follows:
(1) Multi-task mode
All the units connected to the IEBus can transfer data to the other units.
(2) Broadcasting communication function
Communication between one unit and plural units can be performed as follows:
•
Group-unit broadcasting communication: Broadcasting communication to group units
•
All-unit broadcasting communication:
Broadcasting communication to all units.
(3) Effective transfer rate
The effective transfer rate is in mode 1 (the V850/SB2 does not support modes 0 and 2 for the effective
transfer rate).
•
Mode 1: Approx. 17 Kbps
Caution Different modes must not be mixed on one IEBus.
(4) Communication mode
Data transfer is executed in half-duplex asynchronous communication mode.
(5) Access control: CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
The priority of the IEBus is as follows:
<1> Broadcasting communication takes precedence over individual communication (communication from
one unit to another).
<2> The lower master address takes precedence.
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