K60 I2C Multiread

broccolee — Tue, 28 Jun 2016 04:27:56 GMT

I'm using the TWR-K60N512, with PK60DN512Z VMD10 chip to read an IMU: Pololu - MinIMU-9 Gyro, Accelerometer, and Compass (L3G4200D and LSM303DLM Carrier) via I2C.

I am able to perform single read operation with the example I2C driver for kinetis. I'm trying to take the advantage of the address auto-incrementing feature of the sensor, but I can't seem do a multiread operation. I based my code from these two sources: https://community.nxp.com/thread/337809#465606 , and this very useful application note http://cache.nxp.com/files/sensors/doc/app_note/AN4481.pdf, though I think it has errors too.

Here's my modification of the example code:

void LSM303DLM_A_MultiReadRegister(unsigned char u8RegisterAddress, int buffer, unsigned char *result)

{

int i = buffer, j;

/* Send Slave Address */ //SAD + W

IIC_StartTransmission(SlaveID_A,MWSR);

i2c_Wait(); // SAK

/* Write Register Address */ //SUB

I2C0_D = u8RegisterAddress;

i2c_Wait(); // SAK

/* Do a repeated start */ // SR

I2C0_C1 |= I2C_C1_RSTA_MASK;

/* Send Slave Address */ //SAD + R

I2C0_D = (ACCEL_ADDRESS << 1) | 0x01; //read address

i2c_Wait(); // SAK

/* Put in Rx Mode */

I2C0_C1 &= (~I2C_C1_TX_MASK);

//I2C0_C1 |= I2C_C1_TXAK_MASK; // Commented this out

// dummy read

*result = I2C0_D ;

for (j=0; j<5000; j++){};

i2c_Wait();

/************ MODIFICATION BEGINS HERE, EVERYTHING ELSE IS SAME AS EXAMPLE CODE *********/

while(buffer > 2)

{

*result = I2C0_D ;

i2c_Wait();

result++;

buffer--;

Pause();

}

I2C0_C1 |= I2C_C1_TXAK_MASK;

*result = I2C0_D ;

i2c_Wait();

result++;

i2c_Stop();

*(result) = I2C0_D ;

Pause();

}

It returns random values for the first accelerometer measurement and constants for the remaining measurements. Did I get the sequence wrong somewhere?

Thanks.

Re: K60 I2C Multiread

broccolee — Tue, 28 Jun 2016 20:44:36 GMT

Nevermind, it works now. I assumed the I2C_C1_TXAK bit was already cleared so I didn't clear that when switching the module to receiving mode. I cleared it, and it works.

topic K60 I2C Multiread in Kinetis Microcontrollers

K60 I2C Multiread

Re: K60 I2C Multiread