Host Address Detection - Renesas RX100 Series User Manual

RX13T Group
24.7.4

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.
[Host address reception]
S 1 2
SCL0
SDA0
0 0
BBSY
AAS0
AAS1
AAS2
HOA
RDRF
Figure 24.29 HOA Flag Set Timing during Reception of Host Address
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
3 4 5 6 7 8
0 1 0 0 0 W ACK
Receive data (7-bit address)
Read ICDRR register
(Dummy read [7-bit address])
9 1 2 3 4 5
Data (DATA 1)
Host address match (0001 000b)
2
24. I C-bus Interface (RIICa)
6 7 8 9 1 2
ACK
Receive data (DATA 1)
Read ICDRR register
(DATA 1)
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3 4 5
Data (DATA 2)