Inter-Integrated Circuit Controller
7-59
MPU Public Peripherals
7.8.1.3
I
2
C Bus Base Principal
The data on the SDA line must be stable during the high period of the clock.
The high and low states of the data line can only change when the clock signal
on the SCL line is low (see Figure 7–24).
Figure 7–24. Data Validity on the I
2
C Bus
SDA
SCL
Data line
stable,
data valid
Change
of data
allowed
The I
2
C module generates start and stop conditions when it is configured as
a master (see Figure 7–25):
-
Start condition is a high-to-low transition on the SDA line while SCL is high.
-
Stop condition is a low-to-high transition on the SDA line while SCL is high.
The bus is considered busy after the start condition (BB = 1) and free after the
stop condition (BB = 0).
Figure 7–25. Start and Stop Conditions
SDA
SCL
Start
condition (S)
Stop
condition (P)