一、I2C的协议这里就不赘述了，随便搜一下就可以了解。
二、I2C的初始化
1.Enable I2C clock
configure the PSC register(if it is driven by PSC)PSC相关说明可以查看手册
2. Configure the PinMultiplexing registers
3. Place I2C in reset
set IRS =0 in ICMDR register
4.Configure the peripheral clock operation frequency(ICPSC)
NOTE:the frequency should be between 6.7 and 13.3MHz
5.Configure i2c master clock frequency:
configure ICCLKL , ICCLKH
7.Make sure the interrupt status register(ICSTR) is cleared:
Read ICSTR and write it back (write 1 to clear) ICSTR = ICSTR
Read ICIVR until it is 0.
8.Take i2c controller out of reset
set IRS=1 in ICMDR
三、I2C作为master发送数据的配置
1. Wait until bus bit is cleared (BB =0 in ICSTR)
2.Configure ICMDR register
- configure I2C as Master ( MST = 1 );
- indicate the i2c configuration to be used(if TRX = 0, device configured as Data Receiver);
- configure serial data formats( eg. XA = 0, 7-bit addressing format );
- set RM = 0 to disable repeat mode;
- set DLB = 0 to disable loopback mode;
- set FDF = 0 to disable free data format;
- optional:disable start byte mode if addressing a fully fledged i2c device (set STB = 0 );
- set number of bits to transfer to be 8 bits (BC = 0) ;
- 设置仿真器断点无响应，bus继续运行， ICMDR中 FREE=1
3.设置发送数据长度（字节）ICCNT
4.Configure Slave Address( ICSAR = 7bit address)
5.Generate a START event ,followed by Slave Address,etc.(set STT =1 in ICMDR)
6.循环发送数据，数据写入ICDXR，等待ICSTR中ICXRDY=1，表明数据搬运完成。并设置超时重新初始化init（我这设置的是while循环不超过500000）
7. End transfer/release bus when transfer is done. Generate a STOP event (set STP = 1 in ICMDR).
四、I2C作为master读取数据
1. Wait until bus bit is cleared (BB =0 in ICSTR)
2.Configure ICMDR register
- configure I2C as Master ( MST = 1 );
- indicate the i2c configuration to be used(if TRX = 0, device configured as Data Receiver);
- configure serial data formats( eg. XA = 0, 7-bit addressing format );
- set RM = 0 to disable repeat mode;
- set DLB = 0 to disable loopback mode;
- set FDF = 0 to disable free data format;
- optional:disable start byte mode if addressing a fully fledged i2c device (set STB = 0 );
- set number of bits to transfer to be 8 bits (BC = 0) ;
- 设置仿真器断点无响应，bus继续运行， ICMDR中 FREE=1
3.设置发送数据长度（字节）ICCNT
4.Configure Slave Address( ICSAR = 7bit address)
5.Generate a START event ,followed by Slave Address,etc.(set STT =1 in ICMDR)
6.循环接收数据
等待ICSTR中ICRRDY=1，为1时表明数据可以读取，并设置超时重新初始化init（我这设置的是while循环不超过500000），读取ICDRR中数据。当数据为最后一个字节时发送NACK（ICMDR中NACKMOD=1）