怎么从I2C总线读数据_百度知道
怎么从I2C总线读数据
怎么从I2C总线读数据
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i2c有其协议的,我当时从不会到掌握其协议用了一阵子,就是狂读协议和例程我把当时用非斯卡尔单片机读i2c mems传感器的历程写在下面#include &hidef.h& #include &derivative.h&#define IIC_SDA_CTL PTCDD_PTCDD1#define IIC_SDA_DAT PTCD_PTCD1#define IIC_SCL_CTL PTCDD_PTCDD0#define IIC_SCL_DAT PTCD_PTCD0#define IIC_MST_HI 0#define IIC_MST_LO 1void IIC_Start(void);void IIC_Restart(void);void IIC_Stop(void);byte IIC_SendByte(byte);byte IIC_Read(byte *, byte);byte IIC_Write(byte *, byte);void IIC_Delay(void);void IIC_Delay(void){for (i=0;i&8;i++) {}}//==============================================================// Master generates a START condition on IIC bus//==============================================================void IIC_Start(void){IIC_SDA_CTL = IIC_MST_HI;IIC_SCL_CTL = IIC_MST_HI;IIC_Delay();IIC_SDA_CTL = IIC_MST_LO;IIC_SDA_DAT = 0;IIC_Delay();IIC_SCL_CTL = IIC_MST_LO;IIC_SCL_DAT = 0;IIC_Delay();}//==============================================================// Master generates a RESTART condition on IIC bus//==============================================================void IIC_Restart(void){IIC_SDA_CTL = IIC_MST_HI; //SDA back to high while SCL remain in lowIIC_Delay();IIC_SCL_CTL = IIC_MST_HI; //SCL back to high, bus idle nowIIC_Delay();IIC_SDA_CTL = IIC_MST_LO; //RESTART condition occurIIC_Delay();IIC_SCL_CTL = IIC_MST_LO; //SCL to low for standbyIIC_Delay();}//==============================================================// Master generates a STOP condition on IIC bus//==============================================================void IIC_Stop(void){IIC_SDA_CTL = IIC_MST_LO; //make sure SDA is lowIIC_Delay();IIC_SCL_CTL = IIC_MST_HI; //I2C_SCL_CTL go to high firstIIC_Delay();IIC_SDA_CTL = IIC_MST_HI; //I2C_SDA_CTL have low-high transition while SCL is highIIC_Delay();}//==============================================================// Master send out a byte of data and return with ACK/NACK// return with 0x00 if ACK received// return with 0xff if NACK received//==============================================================byte IIC_SendByte(byte outDat){//send out 8-bit datafor (bit=0;bit&8;bit++) {if (outDat&0x80)IIC_SDA_CTL = IIC_MST_HI;elseIIC_SDA_CTL = IIC_MST_LO;IIC_Delay();IIC_SCL_CTL = IIC_MST_HI;IIC_Delay();IIC_SCL_CTL = IIC_MST_LO;outDat &&= 1;}//check for the ACK/NACKIIC_SDA_CTL = IIC_MST_HI; //master release SDAIIC_Delay();IIC_SCL_CTL = IIC_MST_HI; //master send a clockIIC_Delay();if (IIC_SDA_DAT) bit = 0 //NACKelse bit = 0; //ACKIIC_SCL_CTL = IIC_MST_LO;IIC_Delay();return(bit);}//==============================================================// Master write a string of bytes through IIC us// Return with 0x00 if successful// Return with 0xff if failed//==============================================================byte IIC_Write(byte *buff, byte total){while (total) {if (IIC_SendByte(*buff++)) //get NACK after data byte outreturn(0xff); //aborttotal--;//__RESET_WATCHDOG(); //needed only for EEPROM byte-program}return(0);}//==============================================================// Master read a byte of data and set ACK/NACK// return with data read//==============================================================byte IIC_ReadByte(byte ackFlag){byte bit,IIC_SDA_CTL = IIC_MST_HI; //make sure master release SDA//read 8 bits sof datafor (bit=0;bit&8;bit++) {dat &&= 1;IIC_SCL_CTL = IIC_MST_HI;IIC_Delay();if (IIC_SDA_DAT) //read back datadat |= 0x01;IIC_SCL_CTL = IIC_MST_LO;IIC_Delay();}//echo with ACK/NACKif (ackFlag==0) IIC_SDA_CTL = IIC_MST_LO; //echo back ACKelseIIC_SDA_CTL = IIC_MST_HI; //echo back NACKIIC_Delay();IIC_SCL_CTL = IIC_MST_HI;IIC_Delay();IIC_SCL_CTL = IIC_MST_LO;IIC_Delay();return(dat);}//==============================================================// Master read a string of data bytes through IIC us//==============================================================byte IIC_Read(byte *buff, byte total){if (total==0) return(0);if (total==1) { //read one byte onlybuff[0] = IIC_ReadByte(1); //NACK after readreturn(1);}else { //read more than one bytescount = 0;while(total&1) {IIC_Delay();buff[count++] = IIC_ReadByte(0); //ACK after readtotal--;__RESET_WATCHDOG();}IIC_Delay();buff[count++] = IIC_ReadByte(1);return(count);}}然后你去网上搜索iic总线协议,把协议多读几遍慢慢就会了~~要不你把邮箱给我我发给你.总之很简单的
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