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Section 21 IEBus
TM
Controller
R01UH0134EJ0400 Rev. 4.00 Page 1095 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
(b) Acknowledge bit at the End of the Control Field
The acknowledge bit at the end of the control field becomes NAK in the following cases and
transfer is stopped.
When the parity of the control bits is incorrect
When the bit 3 of the control bits is 1 (data write) although the slave receive buffer* is not
empty
When the control bits are set to data read (H'3, H'7) although the slave transmit buffer* is
empty
When another unit which locked the slave unit requests H'3, H'6, H'7, H'A, H'B, H'E, or H'F in
the control bits although the slave unit has been locked
When the control bits are the locked address read (H'4, H'5) although the unit is not locked
When a timing error occurs
When the control bits are undefined
Note: See section 21.1.3 (1), Slave Status Read (Control Bits: H'0, H'6).
(c) Acknowledge Bit at the End of the Message Length Field
The acknowledge bit at the end of the message length field becomes NAK in the following cases
and transfer is stopped.
When the parity of the message length bits is incorrect
When a timing error occurs
(d) Acknowledge Bit at the End of the Data Field
The acknowledge bit at the end of the data field becomes NAK in the following cases and transfer
is stopped.
When the parity of the data bits is incorrect*
When a timing error occurs after the previous transfer of the acknowledge bit
When the receive buffer becomes full and cannot accept further data*
Note: * In this case, the data field is transferred repeatedly until the number of data reaches the
maximum number of transfer bytes if the number of data does not exceed the
maximum number of transfer bytes in one frame.