HMC5883L gibt falsche Werte aus

[Patrick B. (p51d)]

Hallo miteinander
Ich versuche gerade ein wenig mit dem HMC5883L zu spielen. Kommunikation 
läuft soweit, aber leider gibt er mir nicht die richtigen Werte aus. 
Wenn ich eine 180° Drehung mache, dann bekomme ich nur ein Winkel 
zwischen 240 und 300°.
Ich habe mich mitlerweile durch diverse Foren gewühlt, wo Anleitungen zu 
diesem Kompass sind, aber dabei komme ich immer auf den gleichen Wert.

Kann mir jemand sagen, was ich übersehen habe?

void HMC5883L_init(void)
{
    // write CONFIG_A register
    uint8_t tmp = (HMC5883L_AVERAGING_8 << (HMC5883L_CRA_AVERAGE_BIT - HMC5883L_CRA_AVERAGE_LENGTH + 1)) |
                  (HMC5883L_RATE_15 << (HMC5883L_CRA_RATE_BIT - HMC5883L_CRA_RATE_LENGTH + 1)) |
                  (HMC5883L_BIAS_NORMAL << (HMC5883L_CRA_BIAS_BIT - HMC5883L_CRA_BIAS_LENGTH + 1)) ;

    /*ENABLE*/
    I2C_Cmd(HMC5883L_I2C, ENABLE);

    HMC5883L_I2C_ByteWrite(HMC5883L_DEFAULT_ADDRESS, &tmp ,HMC5883L_RA_CONFIG_A);

    // write CONFIG_B register
    HMC5883L_SetGain(HMC5883L_GAIN_1090);

    // write MODE register
    HMC5883L_SetMode(HMC5883L_MODE_SINGLE);
}

void HMC5883L_GetHeading(int16_t* Mag)
{
  uint8_t tmpbuff[6]={0};
  int i = 0;
  HMC5883L_I2C_BufferRead(HMC5883L_DEFAULT_ADDRESS, tmpbuff, HMC5883L_RA_DATAX_H, 6);

  uint8_t tmp = HMC5883L_MODE_SINGLE << (HMC5883L_MODEREG_BIT - HMC5883L_MODEREG_LENGTH + 1);

  if (HMC5883Lmode == HMC5883L_MODE_SINGLE)
    HMC5883L_I2C_ByteWrite(HMC5883L_DEFAULT_ADDRESS, &tmp ,HMC5883L_RA_MODE);
  for(i=0; i<3; i++)
    Mag[i]=((int16_t)((uint16_t)tmpbuff[2*i] << 8) + tmpbuff[2*i+1]);
}
  
systick_ticks = 0;
HMC5883L_GetHeading(MagneticHeading);
Heading = atan2(MagneticHeading[1], MagneticHeading[0]);
declinationAngle = 25.02  / 1000.0;                // Your mrad result / 1000.00 (to turn it into radians).
Heading += declinationAngle;                  // If you have an EAST declination, use += declinationAngle, if you have a WEST declination, use -= declinationAngle
if(Heading < 0)      Heading += 2 * M_PI;          // Correct for when signs are reversed.
if(Heading > (2* M_PI))  Heading -= 2 * M_PI;          // Check for wrap due to addition of declination.
Heading = Heading * (180 / M_PI);                // Convert radians to degrees for readability.
sprintf((char *)buf, "\r\nX: %d\t\tY: %d\t\tZ: %d\t\tHeading: %3.2f",
  (int)MagneticHeading[0], (int)MagneticHeading[1], (int)MagneticHeading[2], Heading);
VCP_send_str(&buf[0]);

Besten Dank für die Antowrt
MFG
Patrick

[Joachim .. (joachim_01)]

Hmmm, weiß jetzt nicht ob dir das weiterhilft... vielleicht ist der 
Kompass falsch parametriert? Sparkfun löst es so:

C-Code

void HMC5843(void)
{    
  uint8_t xh, xl, yh, yl, zh, zl;
  long xo, yo, zo;
  
  i2cSendStart();
  i2cWaitForComplete();
  i2cSendByte(0x3C);    //write to HMC
  i2cWaitForComplete();
  i2cSendByte(0x02);    //mode register
  i2cWaitForComplete();
  i2cSendByte(0x00);    //continuous measurement mode
  i2cWaitForComplete();
  i2cSendStop();
  
  //must read all six registers plus one to move the pointer back to 0x03
  i2cSendStart();
  i2cWaitForComplete();
  i2cSendByte(0x3D);          //read from HMC
  i2cWaitForComplete();
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  xh = i2cGetReceivedByte();  //x high byte
  i2cWaitForComplete();
  //printf(" %d", xh);
  
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  xl = i2cGetReceivedByte();  //x low byte
  i2cWaitForComplete();
  xo = xl|(xh << 8);
  printf("x=%4ld, ", xo);
  
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  yh = i2cGetReceivedByte();  //y high byte
  i2cWaitForComplete();
  //printf(" %d ", yh);
  
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  yl = i2cGetReceivedByte();  //y low byte
  i2cWaitForComplete();
  yo = yl|(yh << 8);
  printf("y=%4ld, ", yo);
  
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  zh = i2cGetReceivedByte();  
  i2cWaitForComplete();      //z high byte
  //printf(" %d ", zh);
  
  i2cReceiveByte(TRUE);
  i2cWaitForComplete();
  zl = i2cGetReceivedByte();  //z low byte
  i2cWaitForComplete();
  zo = zl|(zh << 8);
  printf("z=%ld \r\n", zo);
  
  i2cSendByte(0x3D);         //must reach 0x09 to go back to 0x03
  i2cWaitForComplete();
  
  i2cSendStop();  
}