I²C Start and Stop Conditions

Ordinarily, data on the I2C SDA line is only allowed to change states when the SCL (clock) line is low. This is because transitions on the SDA line while the SCL line is high have special meanings.

Start Condition

A start condition is defined as a transition from high to low on the SDA line while the SCL line is high.

Stop Condition

A stop condition is defined as a transition from low to high on the SDA line while the SCL line is high.

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