Frank Cerasoli

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10 years, 8 months ago.

AUX i2c Connection with the MPU-3050

Hey everyone,

I am using this accelerometer with an MPU-3050 and trying to get the external connection to work.

http://www.seeedstudio.com/depot/Grove-3Axis-Digital-Accelerometer400g-p-1897.html

It seems like I am able to read and write to/from the registers based on the output I'm getting, but the acceleration values make no sense.

Assume that includes and initializations have been made. & paddr = (0x18 << 1) 

void InitializeAccelerometer() {
  char value[5];
  value[0] = 0x7F;
  I2C_Write(paddr, H3LIS331DL_CTRL_REG1, value[0], 1);

  #ifdef OUTPUT_SERIAL
  I2C_Read(paddr, H3LIS331DL_CTRL_REG1, data, 1);
  sc.printf("Written Result: %i\nTemperature: %i\n\n\n", data[0], data[1]);
  #endif

  data[0] = data[1] = 0;

  #ifdef OUTPUT_SERIAL 
  I2C_Read(paddr, H3LIS331DL_WHO_AM_I, data, 1);
  sc.printf("Peripheral Accelerometer Who Am I Test\nI Am: %x\n", data[0]);
  #endif 
}

void SetupAccelerometer ( ) { 
  char value[6];
  value[0] = 0x7F;
  I2C_Write(paddr, H3LIS331DL_CTRL_REG1, value[0], 1);
  #ifdef OUTPUT_SERIAL
  I2C_Read(paddr, H3LIS331DL_CTRL_REG1, value+1, 1);
  sc.printf("Accel CTRL Register: %x\n\n", value[1]);
  #endif

    while (1) {
      I2C_Read(paddr, H3LIS331DL_OUT_X_L, value, 1);
      I2C_Read(paddr, H3LIS331DL_OUT_Y_L, value+1, 1);
      I2C_Read(paddr, H3LIS331DL_OUT_Z_L, value+2, 1);
      #ifdef OUTPUT_SERIAL
      sc.printf("X_L: %i\nY_L: %i\nZ_L: %i\n\n", value[0], value[1], value[2]);
      #endif
      wait(3);
    } 
  }

void I2C_Write ( int addr, char cmd, char value, int length ) {

  i2c.start();
  i2c.write(addr);
  i2c.write(cmd);
  i2c.write(value);
  i2c.stop();

}

void I2C_Read ( int addr, char cmd, char *data, int length ) {
  int result;
  result = i2c.write(addr, &cmd, length, true); 

  #ifdef OUTPUT_READ
  sc.printf("I2C Write Result: %i\n", result);
  #endif

  result = i2c.read(addr, data, length);

  #ifdef OUTPUT_READ
  sc.printf("I2C Read Result: %i\n", result);
  sc.printf("Test: %i\n\r", data[0]);
  #endif
}

The output reads like....

..
Who Am I?

I2C Write Result: 0
I2C Read Result: 0
Test: 105

...... Temperature .......

I2C Write Result: 0
I2C Read Result: 0
Test: 188

MPU Initialized
I2C Write Result: 0
I2C Read Result: 0
Test: 127

Written Result: 127
Temperature: 188


I2C Write Result: 0
I2C Read Result: 0
Test: 50

Peripheral Accelerometer Who Am I Test
I Am: 32
I2C Write Result: 0
I2C Read Result: 0
Test: 255

Accel CTRL Register: ff

Starting Read Routine
I2C Write Result: 0
I2C Read Result: 0
Test: 176

I2C Write Result: 0
I2C Read Result: 0
Test: 160

I2C Write Result: 0
I2C Read Result: 0
Test: 96

X_L: 176
Y_L: 160
Z_L: 96

The X_L, Y_L & Z_L seem to just be gibberish, though.

Please help!

Thanks in advance, Frank

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