IIC Basics

Simply record IIC Related knowledge . Always forget .

First IIC It's two wires ,SDA and SCL,SDA For data transfer ,SCL It's a clock pulse .IIC It is a kind of half duplex communication .

• Hardware connection

By default SDA and SCL Both are in high level and idle state , So these two wires will be connected to Vcc

 

• IIC Several signal definitions of

• Idle signal

When SDA and SCL It's all high level , It is considered to be idle

• Start signal

SCL For the high ,SDA From high to low .

• Stop signal

SCL For the high ,SDA From low to high

• The data transfer

(1) Send the start signal

(2) Data transfer ：SCL For the high ,SDA Stable ( Always high or low )

(3) Data jump ：SCL For low ,SDA Allow jump

(3) Send a termination signal

notes ： During data transmission ,SDA Do not jump , Otherwise it will be considered as the beginning / Stop signal .

 

• Answer signal

This signal indicates , The receiving end receives successfully or unsuccessfully 8 Bytes . When the first 9 A byte high indicates ACK The signal , Indicates the positive response of the receiving end . When the first 9 A low byte indicates NACK The signal , Indicates the negative response of the receiving end .

(1) Start signal

(2) Data transfer (SCL high SDA Stable . SCL low SDA change , Until it was sent 8 position )

(3)SCL Low level ,SDA The signal changes （ The receiving end controls the high and low levels ）

(4)SCL The clock pulse becomes high ,SDA The signal is stable ( Receiving end control ）

(5) The sender detects at 9 individual SCL When the pulse is high SDA The signal

(6)SDA by 1 surface ACK,SDA by 0 surface NACK

 

• Bus President