RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 738 of 1006
Feb 20, 2013
22.3.5
Slave Transmitter Operation
In slave transmitter operation, the master device outputs the SCL (clock) signal, the RIIC transmits data as a slave device,
and the master device returns acknowledgements.
Figure 22.14 shows an example of usage of slave transmission and figures 22.15 and 22.16 show the timing of operations
in slave transmission.
The following describes the procedure and operations for slave transmission.
1. Follow the procedure in figure 22.5 to make initial settings for the RIIC. This step is not necessary if initialization of
the RIIC has already been completed. After initial settings, the RIIC will stay in the standby state until it receives a
slave address that it matches.
2. After receiving a matching slave address, the RIIC sets one of the corresponding bits ICSR1.HOA, GCA, and AASy
(y = 0 to 2) to 1 on the rising edge of the ninth cycle of SCL clock (the clock signal) and outputs the value set in the
ICMR3.ACKBT bit to the acknowledge bit on the ninth cycle of SCL clock. If the value of the R/W# bit that was also
received at this time is 1, the RIIC automatically places itself in slave transmitter mode by setting both the TRS bit
and the TDRE flag in ICSR2 to 1.
3. After the ICSR2.TEND flag is confirmed to be 1, write the data for transmission to the ICDRT register. At this time,
if the RIIC receives no acknowledge from the master device (receives an NACK signal) while the ICFER.NACKE bit
is 1, the RIIC suspends transfer of the next data.
4. Wait unit the ICSR2.TEND flag is set to 1 while the ICSR2.TDRE flag is 1, after the ICSR2.NACKF flag is set to
1or the last byte for transmission is written to the ICDRT register. When the ICSR2.NACKF flag or the TEND flag is
1, the RIIC drives the SCLn line low on the ninth falling edge of SCL clock.
5. When the ICSR2.NACKF flag or the ICSR2.TEND flag is 1, dummy read ICDRR to complete the processing. This
releases the SCLn line.
6. Upon detecting the stop condition, the RIIC automatically clears bits ICSR1.HOA, GCA, and AASy (y = 0 to 2),
flags ICSR2.TDRE and TEND, and the ICCR2.TRS bit to 0, and enters slave receiver mode.
7. After checking that the ICSR2.STOP flag is 1, clear the ICSR2.NACKF and STOP flags to 0 for the next transfer
operation.