R01UH0823EJ0100 Rev.1.00 Page 1169 of 1823
Jul 31, 2019
RX23W Group 35. I
2
C-bus Interface (RIICa)
35.7.4 Host Address Detection
The RIIC has a function to detect the host address while the SMBus is operating. When the ICSER.HOAE bit is set to 1
while the ICMR3.SMBS bit is 1, the RIIC can detect the host address (0001 000b) in slave receive mode (bits MST and
TRS in the ICCR2 register are 00b).
When the RIIC detects the host address, the ICSR1.HOA flag is set to 1 at the rising edge of the ninth SCL clock cycle,
and at the same time, the ICSR2.RDRF flag is set to 1 when the R/W# bit is 0 (Wr bit). This causes a receive data full
interrupt (RXI) to be generated. The HOA flag is used to recognize that the host address was sent from the smart battery
or other devices.
If the bit following the host address (0001 000b) is an Rd bit (R/W# bit is 1), the RIIC can also detect the host address.
After the host address is detected, the RIIC operates in the same manner as normal slave operation.
Figure 35.29 HOA Flag Set Timing during Reception of Host Address
Read ICDRR register
(Dummy read [7-bit address])
AAS2
AAS0
S
1
AAS1
9
ACK
BBSY
RDRF
234567
8 9
ACK
1
[Host address reception]
1
0
HOA
234567
001000
8
W
2345
Data (DATA 1) Data (DATA 2)
Read ICDRR register
(DATA 1)
Receive data (7-bit address) Receive data (DATA 1)
Host address match (0001 000b)
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