Rev. 3.00 Jan 25, 2006 page xiv of lii
Item
Page
Revision (See Manual for Details)
17.7 Usage Notes
550,
551
16. Notes on Arbitration Lost
The I
2
C bus interface recognizes the data in transmit/receive
frame as an address when arbitration is lost in master mode
and a transition to slave receive mode is automatically carried
out.
When arbitration is lost not in the first frame but in the second
frame or subsequent frame, transmit/receive data that is not an
address is compared with the value set in the SAR or SARX
register as an address. If the receive data matches with the
address in the SAR or SARX register, the I
2
C bus interface
erroneously recognizes that the address call has occurred. (See
figure 17.29.)
In multi-master mode, a bus conflict could happen. When The
I
2
C bus interface is operated in master mode, check the state of
the AL bit in the ICSR register every time after one frame of
data has been transmitted or received.
When arbitration is lost during transmitting the second frame or
subsequent frame, take avoidance measures.
S
SLA
R/
W
S
SLA
R/
W
A
DATA2
S
SLA
R/
W
A
SLA
R/
W
A
DATA3
A
DATA4
DATA1
I
2
C bus interface
(Master transmit mode)
Transmit data match
Transmit timing match
• Receive address is ignored
• Automatically transferred to slave
receive mode
• Receive data is recognized as
an address
• When the receive data matches to
the address set in the SAR or SARX
register, the I
2
C bus interface operates
as a slave device
• Arbitration is lost
• The AL flag in ICSR is set to 1
Transmit data does not match
Other device
(Master transmit mode)
I
2
C bus interface
(Slave receive mode)
Data contention
A
A
A
Figure 17.29 Diagram of Erroneous Operation when
Arbitration is Lost
Though it is prohibited in the normal I
2
C protocol, the same
problem may occur when the MST bit is erroneously set to 1
and a transition to master mode is occurred during data
transmission or reception in slave mode. In multi-master mode,
pay attention to the setting of the MST bit when a bus conflict
may occur. In this case, the MST bit in the ICCR register should
be set to 1 according to the order below.
(a) Make sure that the BBSY flag in the ICCR register is 0 and
the bus is free before setting the MST bit.
Summary of Contents for H8S/2158
Page 10: ...Rev 3 00 Jan 25 2006 page viii of lii...
Page 36: ...Rev 3 00 Jan 25 2006 page xxxiv of lii B Product Lineup 863 C Package Dimensions 864 Index 865...
Page 47: ...Rev 3 00 Jan 25 2006 page xlv of lii Appendix Figure C 1 Package Dimensions TBP 112A 864...
Page 54: ...Rev 3 00 Jan 25 2006 page lii of lii...
Page 70: ...Section 1 Overview Rev 3 00 Jan 25 2006 page 16 of 872 REJ09B0286 0300...
Page 118: ...Section 3 MCU Operating Modes Rev 3 00 Jan 25 2006 page 64 of 872 REJ09B0286 0300...
Page 126: ...Section 4 Exception Handling Rev 3 00 Jan 25 2006 page 72 of 872 REJ09B0286 0300...
Page 198: ...Section 6 Bus Controller Rev 3 00 Jan 25 2006 page 144 of 872 REJ09B0286 0300...
Page 326: ...Section 10 8 Bit PWM Timer PWM Rev 3 00 Jan 25 2006 page 272 of 872 REJ09B0286 0300...
Page 440: ...Section 15 Watchdog Timer WDT Rev 3 00 Jan 25 2006 page 386 of 872 REJ09B0286 0300...
Page 606: ...Section 17 I 2 C Bus Interface IIC Rev 3 00 Jan 25 2006 page 552 of 872 REJ09B0286 0300...
Page 742: ...Section 19 Multimedia Card Interface MCIF Rev 3 00 Jan 25 2006 page 688 of 872 REJ09B0286 0300...
Page 750: ...Section 21 D A Converter Rev 3 00 Jan 25 2006 page 696 of 872 REJ09B0286 0300...
Page 768: ...Section 22 A D Converter Rev 3 00 Jan 25 2006 page 714 of 872 REJ09B0286 0300...
Page 770: ...Section 23 RAM Rev 3 00 Jan 25 2006 page 716 of 872 REJ09B0286 0300...
Page 824: ...Section 26 Clock Pulse Generator Rev 3 00 Jan 25 2006 page 770 of 872 REJ09B0286 0300...
Page 844: ...Section 27 Power Down Modes Rev 3 00 Jan 25 2006 page 790 of 872 REJ09B0286 0300...
Page 878: ...Section 28 List of Registers Rev 3 00 Jan 25 2006 page 824 of 872 REJ09B0286 0300...
Page 926: ...Index Rev 3 00 Jan 25 2006 page 872 of 872 REJ09B0286 0300...