RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 750 of 1006
Feb 20, 2013
22.7.3
Device-ID Address Detection
The RIIC module has a facility for detecting device-ID addresses conformant with the I
2
C bus specification (Rev. 03).
When the RIIC receives 1111 100b as the first byte after a start condition or restart condition was issued with the DIDE
bit in ICSER set to 1, the RIIC recognizes the address as a device ID, sets the DID flag in ICSR1 to 1 on the rising edge
of the ninth SCL clock cycle when the following R/W# bit is 0, and then compares the second and subsequent bytes with
its own slave address. If the address matches the value in the slave address register, the RIIC sets the corresponding
AASy flag (y = 0 to 2) in ICSR1 to 1.
After that, when the first byte received after a restart condition is issued matches the device ID address (1111 100b) again
and the following R/W# bit is 1, the RIIC does not compare the second and subsequent bytes and sets the ICSR2.TDRE
flag to 1.
In the device-ID address detection function, the RIIC clears the DID flag to 0 if a match with the RIIC's own slave
address is not obtained or a match with the device ID address is not obtained after a match with the RIIC's own slave
address and the detection of a restart condition. If the first byte after detection of a start or restart condition matches the
device ID address (1111 100b) and the R/W# bit is 0, the RIIC sets the DID flag to 1 and compares the second and
subsequent bytes with the RIIC's slave address. If the R/W# bit is 1, the DID flag holds the previous value and the RIIC
does not compare the second and subsequent bytes. Therefore, the reception of a device-ID address can be checked by
reading the DID flag after confirming that TDRE = 1.
Furthermore, prepare the device-ID fields (three bytes: 12 bits indicating the manufa 9 bits identifying the part +
3 bits indicating the revision) that must be sent to the host after reception of a continuous device-ID field as normal data
for transmission. For details of the information that must be included in device-ID fields, contact NXP Semiconductors.