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CHAPTER 17
IEBus CONTROLLER (
PD178096A, 178098A, 178F098 ONLY)
User’s Manual U12790EJ2V0UD
(a) Acknowledge bit at end of slave address field
The acknowledge bit at the end of the slave address field serves as NACK in any of the following cases,
and transmission is stopped.
If the parity of the master address bit or slave address bit is incorrect
If a timing error (error in bit format) occurs
If a slave unit does not exist
(b) Acknowledge bit at end of control field
The acknowledge bit at the end of the control field serves as NACK in any of the following cases, and
transmission is stopped.
If the parity of the control bit is incorrect
If control bit 3 is ‘1’ (write operation) when the slave reception enable flag (ENSLVRX) is not set (1) (refer
to 17.4.2 (1) IEBus control register 0 (BCR0))
If the control bit indicates reading of data (3H or 7H) when the slave transmission enable flag (ENSLVTX)
is not set (1) (refer to 17.4.2 (1) IEBus control register 0 (BCR0))
If a unit other than the one that set locking requests control bits 3H, 6H, 7H, AH, BH, EH, or FH when
locking is set
If the control bit indicates reading of a lock address (4H or 5H) even when locking is not set
If a timing error occurs
If the control bit is undefined
Cautions 1. Even when the slave transmission enable flag (ENSLVTX) is not set (1), ACK may be
returned if control data is received (refer to Table 17-5).
2. Even when the slave reception enable flag (ENSLVRX) is not set (1), NACK is always
returned by the acknowledge bit in the control field if data/command writing control
data is acknowledged.
Slave reception can be disabled (communication stopped) by the ENSLVRX flag only
in the case of individual communication. In the case of broadcast communication,
communication is maintained and the data request interrupt (INTIE1) or IEBus end
interrupt (INTIE2) is generated.