Datasheet

Section 16 I
2
C Bus Interface [H8S/2138 Group Option]
Rev. 4.00 Jun 06, 2006 page 485 of 1004
REJ09B0301-0400
16.3 Operation
16.3.1 I
2
C Bus Data Format
The I
2
C bus interface has serial and I
2
C bus formats.
The I
2
C bus formats are addressing formats with an acknowledge bit. These are shown in (a) and
(b) in figure 16.3. The first frame following a start condition always consists of 8 bits.
IIC channel 0 only is capable of formatless operation, as shown in figure 16.4.
The serial format is a non-addressing format with no acknowledge bit. This is shown in figure
16.5.
Figure 16.6 shows the I
2
C bus timing.
The symbols used in figures 16.3 to 16.6 are explained in table 16.4.
S SLA R/W A DATA A A/A P
1111
n7
1 m
(a) I
2
C bus format (FS = 0 or FSX = 0)
(b) I
2
C bus format (start condition retransmission, FS = 0 or FSX = 0)
transfer bit count
(n = 1 to 8)
transfer frame count
(m ≥ 1)
S SLA R/W A DATA
111
n17
1 m1
S SLA R/W A DATA A/A P
111
n27
1 m2
111
A/A
transfer bit count (n1 and n2 = 1 to 8)
transfer frame count (m1 and m2 ≥ 1)
11
Figure 16.3 I
2
C Bus Data Formats (I
2
C Bus Formats)