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Section 17 I
2
C Bus Interface 3
Page 876 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
17.4.5 Slave Receive Operation
In slave receive mode, the master device outputs the transmit clock and transmit data, and the
slave device returns an acknowledge signal. For slave receive mode operation timing, refer to
figures 17.11 and 17.12. The reception procedure and operations in slave receive mode are
described below.
1. Set the ICE bit in ICCR1 to 1. Set bits CKS[3:0] in ICCR1. (Initial setting) Set the MST and
TRS bits in ICCR1 to select slave receive mode, and wait until the slave address matches.
2. When the slave address matches in the first frame following detection of the start condition,
the slave device outputs the level specified by ACKBT in ICIER to SDA, at the rise of the 9th
clock pulse. At the same time, RDRF in ICSR is set to read ICDRR (dummy read). (Since the
read data show the slave address and R/W, it is not used.)
3. Read ICDRR every time RDRF is set. If 8th receive clock pulse falls while RDRF is 1, SCL is
fixed low until ICDRR is read. The change of the acknowledge before reading ICDRR, to be
returned to the master device, is reflected to the next transmit frame.
4. The last byte data is read by reading ICDRR.
ICDRS
ICDRR
12 134567899
A
A
RDRF
Data 1
Data 2
Data 1
SCL
(Master output)
SDA
(Master output)
SDA
(Slave output)
SCL
(Slave output)
Bit 7 Bit 7Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
[2] Read ICDRR (dummy read)
[2] Read ICDRR
User
processing
Figure 17.11 Slave Receive Mode Operation Timing (1)