topic Re: i2c0 reading wrong data in Kinetis Design Studio

i2c0 reading wrong data

bharadwaaj — Sat, 17 Oct 2015 06:07:36 GMT

Hi i am trying to interface KEA128 with accelerometer(MMA8451) or magneto meter (MAG3310) am having trouble reading who am i register getting wrong values have attached the project below using code warrior.

Original Attachment has been moved to: file.zip

Re: i2c0 reading wrong data

Alice_Yang — Mon, 19 Oct 2015 02:04:02 GMT

Hello Bharadwaaj,

Could you pleas describe the the problem In detail , that can find the problem faster .

Alice

Re: i2c0 reading wrong data

bharadwaaj — Wed, 21 Oct 2015 06:40:08 GMT

Hi with the below code we are trying to read the Who am i register of MAG3310(slave address is: 0x0e) I am trying to read the who am i register (reg address is: 0x07).

I am supposed to read 0xC4 but am getting 0x1D.

uint8_t I2C_MasterRegisterReadWait(I2C_Type *pI2Cx,uint8_t u8SlaveAddress, uint8_t u8RegisterAddress,uint8_t *pRdBuff)

{

uint8_t u8ErrorStatus=0;

/* send start signals to bus */

u8ErrorStatus = I2C_Start(pI2Cx);

/* send device address to slave */

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8SlaveAddress<<1) | I2C_WRITE);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8RegisterAddress) );

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_RepeatStart(pI2Cx);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8SlaveAddress<<1) | I2C_READ);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

/* if no error occur, received the correct ack from slave

continue to send data to slave

/* dummy read one byte to switch to Rx mode */

I2C_ReadOneByte(pI2Cx,&pRdBuff[0],I2C_SEND_NACK);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

/* send stop signals to bus */

u8ErrorStatus = I2C_Stop(pI2Cx);

return u8ErrorStatus;

}

Re: i2c0 reading wrong data

Alice_Yang — Wed, 21 Oct 2015 12:42:22 GMT

Hello

I have check the datasheet of MAG3310 , the data of 0X1D is the read address , so are you sue you checked the data is the register of "Who am i" ?

And i fund in you IIC file , there is a function of " I2C_MasterReadWait()" , if use this function , what about the result ?

Alice

Re: i2c0 reading wrong data

bharadwaaj — Thu, 22 Oct 2015 07:12:59 GMT

Hi i forgot to add the dummy read thats why it was giving random values if we read from the bus now i have changed my code in order to make dummy read and then read now it works fine.... This above code is not from iic driver file. I have written this register read functionality in order to read from register....

uint8_t I2C_MasterRegisterReadWait(I2C_Type *pI2Cx,uint8_t u8SlaveAddress, uint8_t u8RegisterAddress,uint8_t *pRdBuff)

{

uint8_t u8ErrorStatus=0;

/* send start signals to bus */

u8ErrorStatus = I2C_Start(pI2Cx);

/* send device address to slave */

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8SlaveAddress<<1) | I2C_WRITE);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8RegisterAddress) );

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_RepeatStart(pI2Cx);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_WriteOneByte(pI2Cx,((uint8_t)u8SlaveAddress<<1) | I2C_READ);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

/* if no error occur, received the correct ack from slave

continue to send data to slave

/* dummy read one byte to switch to Rx mode */

u8ErrorStatus = I2C_ReadOneByte(pI2Cx,&pRdBuff[0],I2C_SEND_NACK);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

u8ErrorStatus = I2C_ReadOneByte(pI2Cx,&pRdBuff[0],I2C_SEND_NACK);

if( u8ErrorStatus != I2C_ERROR_NULL )

{

return u8ErrorStatus;

}

/* send stop signals to bus */

u8ErrorStatus = I2C_Stop(pI2Cx);

return u8ErrorStatus;

}