Specifications

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communications at the same time, which would cause data collision and
corruption.
Figure 3.2.1-3 I²C Start and Stop Clock Conditions, reprinted with permission
from NXP Semiconductor
A valid session of data transfer is represented in Figure 3.2.1-4. In this session,
the master device creates a START condition, then transfers the first byte of
data, which is the address of the slave device the master would like to initiate
communications with. The next part of the transmission represents the direction
of communications, where a logical HIGH represents a read transaction and a
logical LOW represents a write transaction. After this initial message, the master
releases control of the SDA line, bringing it to a logical HIGH. If the slave device
is present on the bus, it will send an ACK message by pulling the SDA line to a
logical LOW. After the slave has sent the ACK message, the master begins to
send data one byte at a time, followed immediately by a START condition to
signal a continued data transaction, or a STOP condition to signal an end to the
data transaction.
Figure 3.2.1-4 Data transfer on the I²C bus, reprinted with permission from NXP
Semiconductor