RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 768 of 1006
Feb 20, 2013
If the period measured with the TPU or TMR exceeds the total clock low-level extended period [master device] T
LOW:
MEXT
: 10 ms (max.) of the SMBus standard or the total of measured periods exceeds the clock low-level detection timeout
T
TIMEOUT
: 25 ms (min.) of the SMBus standard, the master device must stop the transaction by issuing a stop condition. In
master transmit mode, immediately stop the transmit operation (writing data to ICDRT).
S
1
1
P
9
9
8
R/W
7
7-bit slave address
2
9
7
Data
2
8
7
2
8
7
2
8
7
Data
2
8
1
Start
Stop
Clk
ACK
Measured with the TPU or TMR
T
LOW SEXT
Clk
ACK
T
LOW MEXT
T
LOW MEXT
Clk
ACK
T
LOW MEXT
TEND
TDRE
BBSY
RDRF
SCLn
SDAn
START
STOP
RDRFS
T
LOW MEXT
T
LOW SEXT
: Total clock low-level extended period (slave device)
T
LOW MEXT
: Total clock low-level extended period (master device)
SMBus standard
ACK
ACK
A/NA
Figure 22.40 SMBus Timeout Measurement
22.12.2 Packet Error Code (PEC)
The RX610 Group incorporates a CRC operation circuit. The CRC operation circuit enables transmission of a packet
error code (PEC) or checking the received data of the SMBus in data communication of the RIIC. For the CRC
generating polynomials of the CRC operation circuit, see section 21, CRC Operation Circuit (CRC).
The PEC data in master transmit mode (master transmitter) can be generated by writing all transmit data to the CRC data
input register (CRCDIR) in the CRC operation circuit.
The REC data in master receive mode (master receiver) can be checked by writing all receive data to CRCDIR in the
CRC operation circuit and comparing the obtained value in the CRC data output register (CRCDOR) with the received
PEC data.
To send ACK or NACK according to the match or mismatch result when the final byte is received as a result of the PEC
code check, set the RDRFS bit in ICMR3 to 1 before the rising edge of the eighth SMBCLK clock cycle during reception
of the final byte, and hold the SCLn line low at the falling edge of the eighth clock cycle.
Summary of Contents for RX600 Series
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