kriswiner/MPU9250

Sensitivity Adjustment

Overff opened this issue · 3 comments

Overff commented

Hi. First of all I would like to say thank you for the project!
Could you explain your way to calculate the sensitivity adjustment for magnetometer (AK8963)?
MPU-9250 Register Map and Descriptions Revision: 1.6 says how to do it (see the attache)
1_1
It looks like you ignored to do (ASA-128). Why?

I guess it should be

uint8_t ASAX_magXAdjust, ASAY_magYAdjust, ASAZ_magZAdjust;
...
Wire.beginTransmission(0x0C);
  Wire.write(0x10);
  Wire.endTransmission();
  Wire.requestFrom(0x0C, 3); 
  /*
   * The AK8963 has a read-only Fuse ROM Access mode that allows the access to the Fuse ROM data. 
   * The Fuse ROM contains the sensitivity adjustment data for each axis.
   */
  ASAX_magXAdjust = Wire.read();  // ASAX X-axis sensitivity adjustment 
  ASAY_magYAdjust = Wire.read();  // ASAY Y-axis sensitivity adjustment 
  ASAZ_magZAdjust = Wire.read();  // ASAZ Z-axis sensitivity adjustment 
...

  magCalibration[0]= (float)rawData[0] * ((((float)**ASAX_magXAdjust** - 128)/256)+1);
  magCalibration[1] = (float)rawData[1] * ((((float)**ASAY_magYAdjust** - 128)/256)+1);
  magCalibration[2] = (float)rawData[2] * ((((float)**ASAZ_magZAdjust** - 128)/256)+1);

This is your code

void MPU9250::initAK8963(uint8_t Mscale, uint8_t Mmode, float * magCalibration)
{
  // First extract the factory calibration for each magnetometer axis
  uint8_t rawData[3];  // x/y/z gyro calibration data stored here
  writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer  
  delay(10);
  writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode
  delay(10);
  readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]);  // Read the x-, y-, and z-axis calibration values
  magCalibration[0] =  (float)(**rawData[0] - 128**)/256.0f + 1.0f;   // Return x-axis sensitivity adjustment values, etc.
  magCalibration[1] =  (float)(**rawData[1] - 128**)/256.0f + 1.0f;  
  magCalibration[2] =  (float)(**rawData[2] - 128**)/256.0f + 1.0f; 
  _magCalibration[0] = magCalibration[0];
  _magCalibration[1] = magCalibration[1];
  _magCalibration[2] = magCalibration[2];
  _Mmode = Mmode;
  writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer  
  delay(10);
  // Configure the magnetometer for continuous read and highest resolution
  // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register,
  // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates
  writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR
  delay(10);
}
kriswiner commented
Overff commented

So what is your question?

Where in your code are ASAX, ASAY, ASAZ?

kriswiner commented