I2C模块应用篇（查询法）

wu68aq · 发表于 2016-6-28 15:05

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F282xx/F283xx自身带有I2C模块，但受限于TI的官方例程中使用了fifo,其深度为4，在写EEPROM时，读写地址16位，占了2个字节，最多只留下2个字节存储数据，使用很不方便、实用性也极差。有不少网友在这一块碰壁，甚至逼的没办法使用IO口模拟I2C，放弃使用I2C模块。最近一直在测试28027的I2C模块有所获，可突破发送/接收长度限制（非fifo模式，当然这个长度也要和I2C器件匹）。本查介绍查询方式下的I2C模块使。
1、宏定义I2C模块操作参数
#define I2C_SLAVE_ADDR       0x50 //器件地址不含读写位。以24Cxx系列为例，器件地址应为：(0xA0>>1)，即0x50
#define I2C_NUMBYTES       10       //发送/接收数据长度
#define I2C_EEPROM_HIGH_ADDR  0x00
#define I2C_EEPROM_LOW_ADDR 0x00

2、设置相应GPIO引脚用作I2C引脚。修改F2802x_I2C.c文件中的void InitI2CGpio()函数。
3、初始化I2C模块。
void I2CA_Init(void)
{
// Initialize I2C
I2caRegs.I2CSAR = 0x0050;       // Slave address - EEPROM control code

// I2CCLK = SYSCLK/(I2CPSC+1)
#if (CPU_FRQ_40MHZ||CPU_FRQ_50MHZ)
   I2caRegs.I2CPSC.all = 4;    // Prescaler - need 7-12 Mhz on module clk
#endif

#if (CPU_FRQ_60MHZ)
   I2caRegs.I2CPSC.all = 6;    // Prescaler - need 7-12 Mhz on module clk
#endif
I2caRegs.I2CCLKL = 10;          // NOTE: must be non zero
I2caRegs.I2CCLKH = 5;          // NOTE: must be non zero
I2caRegs.I2CIER.all = 0x00;    // Enable SCD & ARDY interrupts

I2caRegs.I2CMDR.all = 0x0020; // Take I2C out of reset
                                 // Stop I2C when suspended

I2caRegs.I2CFFTX.all = 0x0000; // Enable FIFO mode and TXFIFO
I2caRegs.I2CFFRX.all = 0x0000; // Enable RXFIFO, clear RXFFINT,

return;
}
4、执行I2C模块接收或者发送。
//I2C模块发送数据到I2C器件。
void  I2CA_SendData(void)
{
         Uint16 i;
         I2caRegs.I2CSAR = I2C_SLAVE_ADDR;                      //Set slave address
         I2caRegs.I2CCNT = I2C_NUMBYTES + 2;                      //Set count to 5 characters plus 2 address bytes
         I2caRegs.I2CDXR = I2C_EEPROM_HIGH_ADDR;                      //Send eeprom high address
         I2caRegs.I2CMDR.bit.TRX = 1;                               //Set to Transmit mode
         I2caRegs.I2CMDR.bit.MST = 1;                               //Set to Master mode
         I2caRegs.I2CMDR.bit.FREE = 1;                               //Run in FREE mode
         I2caRegs.I2CMDR.bit.STP = 1;                               //Stop when internal counter becomes 0
         I2caRegs.I2CMDR.bit.STT = 1;                               //Send the start bit, transmission will follow
         while(I2caRegs.I2CSTR.bit.XRDY == 0){};                //Do nothing till data is shifted out
         I2caRegs.I2CDXR = I2C_EEPROM_LOW_ADDR;                         //Send eeprom low address

         for(i = 0; i < I2C_NUMBYTES; i++){
               while(I2caRegs.I2CSTR.bit.XRDY == 0){};       //Do nothing till data is shifted out
               I2caRegs.I2CDXR = TxdData;                                        //Send out the message
         }
}
//I2C模块从I2C器件接收数据。
void  I2CA_ReceiveData(void)
{
         Uint16 i;
         I2caRegs.I2CSAR = I2C_SLAVE_ADDR;                      //Set slave address
         I2caRegs.I2CCNT = 2;                                              //Set count to 2 address bytes
         I2caRegs.I2CDXR = I2C_EEPROM_HIGH_ADDR;                      //Send eeprom high address
         I2caRegs.I2CMDR.bit.TRX = 1;                               //Set to Transmit mode
         I2caRegs.I2CMDR.bit.MST = 1;                               //Set to Master mode
         I2caRegs.I2CMDR.bit.FREE = 1;                               //Run in FREE mode
         I2caRegs.I2CMDR.bit.STP = 0;                               //Dont release the bus after Tx
         I2caRegs.I2CMDR.bit.STT = 1;                               //Send the start bit, transmission will follow

         while(I2caRegs.I2CSTR.bit.XRDY == 0){};                //Do nothing till data is shifted out
         I2caRegs.I2CDXR = I2C_EEPROM_LOW_ADDR;                      //Send eeprom low address
         I2caRegs.I2CCNT = I2C_NUMBYTES;                               //read 5 bytes from eeprom
         I2caRegs.I2CMDR.bit.TRX = 0;                               //Set to Recieve mode
         I2caRegs.I2CMDR.bit.MST = 1;                               //Set to Master mode
         I2caRegs.I2CMDR.bit.FREE = 1;                               //Run in FREE mode
         I2caRegs.I2CMDR.bit.STP = 1;                               //Stop when internal counter becomes 0
         I2caRegs.I2CMDR.bit.STT = 1; //Repeated start, Reception will follow
         for(i = 0; i < I2C_NUMBYTES; i++){
               while(I2caRegs.I2CSTR.bit.RRDY == 0){};       //I2CDRR not ready to read?
               RxdData = I2caRegs.I2CDRR;
         }
}

Titianyeer · 发表于 2016-6-29 10:11

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I2C模块应用篇（查询法）

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