CHAPTER 18 IEBus CONTROLLER (V850/SC2)
526
User’s Manual U15109EJ3V0UD
(a) Communication enable flag (ENIEBUS)...Bit 7
<Set/reset conditions>
Set:
By software
Reset: By software
Caution
Make both of the following settings before setting the ENIEBUS flag.
••••
Set the interrupt enable (EI) status and enable interrupt servicing 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 broadcast communication, always set the ALLRQ flag, then the MSTRQ
flag.