CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
440
(3) Master address field
The master address field is output by the master to inform a slave of the master’s address.
The configuration of the master address field is as shown in Figure 19-2.
If two or more units start transmitting the broadcasting bit at the same time, the master address field makes a
judgment of arbitration.
The master address field compares the data it outputs with the data on the bus each time it has output one
bit. If the master address output by the master address field is found to be different from the data on the bus
as a result of comparison, it is assumed that the master has lost in arbitration. As a result, the master stops
transmission and enters the reception status.
Because the IEBus is configured of wired AND, the unit having the minimum master address of the units
participating in arbitration (arbitration masters) wins in arbitration.
After a 12-bit master address has been output, only one unit remains in the transmission status as one
master unit.
Next, this master unit outputs a parity bit, determines the master address of other unit, and starts outputting a
slave address field.
If one unit occupies the bus as the master, the address set by the IEBus unit address register (UAR) is
output.
Figure 19-2. Master Address Field
Master address field
Master address (12 bits)
MSB
LSB
Parity
Содержание MPD703030A
Страница 2: ...User s Manual U13850EJ4V0UM 2 MEMO ...
Страница 514: ...User s Manual U13850EJ4V0UM 514 MEMO ...