CHAPTER 18 IEBus CONTROLLER (V850/SC2)
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User’s Manual U15109EJ3V0UD
(e) Lock status flag (LOCK)...Bit 2
A flag that indicates whether the unit is locked.
<Set/reset conditions>
Set:
When the communication end flag goes low level and the frame end flag goes high level after
receipt of a lock specification (3H, 6H, AH, BH) in the control field.
Reset: When the communication enable flag is cleared.
When the communication end flag is set after receipt of a lock release (3H, 6H, AH, BH) in the
control field.
Caution
Lock specification/release is not possible in broadcast communication. Also, in locked
status, individual communication from a unit other than the unit which has requested to
be locked is not acknowledged. However, even communication from a unit which has
not requested to be locked can be acknowledged as long as the communication is a
slave status request.
(9) IEBus interrupt status register (ISR)
This register indicates the status when the IEBus issues an interrupt. The ISR is read to generate an interrupt,
after which the specified interrupt servicing is carried out.
Reset the ISR register after reading it. Until it is reset, the INTIE2 interrupt signal is not generated (nor held
pending).
To reset the ISR register, reset each flag, satisfying the reset conditions in Table 18-8.
Table 18-8. Reset Conditions of Flags in ISR Register
Flag Name
Reset Condition
Processing Example
IEERR, STARTF, STATUSF
Byte write operation of ISR register. Any value
can be written.
ISR = 00H, etc.
ENDTRNS, ENDFRAM
Set MSTRQ, ENSLVTX, or ENSLVRX flag.
BCR register = 88H or ENSLVTX
= 1, etc.
Caution
Even if 0 is written to the ENDTRNS or ENDFRAM flag by accessing the ISR register, these
flags are not reset. Reset them as described above.
Remark
MSTRQ:
Bit 6 of the IEBus control register (BCR)
ENSLVTX:
Bit 4 of the IEBus control register (BCR)
ENSLVRX: Bit 3 of the IEBus control register (BCR)