CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
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(a) Communication enable flag (ENIEBUS)...Bit 7
<Set/reset conditions>
Set:
By software
Reset: By software
Caution Before setting the ENIBUS flag, make the following setting:
•
Set the interrupt enabled (EI) status and enable the interrupt processing of INTIE2
(IEBMK = 2).
••••
Set the IEBus unit address register (UAR)
(b) Master request flag (MSTRQ)...Bit 6
<Set/reset conditions>
Set:
By software
Reset: By hardware, at the end of the arbitration period. Because the reset signal is generated in the
ACK period of the slave address field, if a MSTRQ flag setting instruction is sent in this period,
it will be invalid.
Cautions 1. The master request should be resent by software following a loss in arbitration.
When resending the master request in this case, set (1) the MSTRQ flag after securing
the required wait period. This flag is unable to be set (1) before the end of this wait
period.
INTIE2 interrupt signal
Start interrupt generation
Forcible reset period
Wait period (61.7 s MAX)
µ
MSTRQ flag
reset signal
2. When a master request has been sent and bus mastership acquired, do not set the
MSTRQ, ENSLVTX, or ENSLVRX flag until the end of communication (i.e. the ISR
register’s communication end/frame end flag is set (1)) as setting these flags disables
interrupt request generation. However, these flags can be set if communication has
been aborted.
(c) Broadcast request flag (ALLRQ)...Bit 5
<Set/reset conditions>
Set:
By software
Reset: By software
Caution When requesting broadcasting communication, always set the ALLRQ flag, then the
MSTRQ flag.