CMPS10 heading changes when tilted

[eclipsh]

My CMPS10 was working fine for a while. When I was rewiring my system I accidentally wired the I2C pins to mode and factory use instead of the communication pins. Now the heading changes dramatically when the compass is tilted. The pitch and yaw functions still read out fine. Is the magnetometer damaged or did some software get scrambled? I tried resetting to factory specs but may have done it wrong. Here is the code I used:

void reset(){
Wire.beginTransmission(deviceId);
Wire.write(22);
delay(10);
Wire.write(0x20);
delay(100);
Wire.write(0x2A);
delay(100);
Wire.write(0x60);
Wire.endTransmission();
delay(100);

Serial.println("done");

}


This is running on an Arduino Mega with 5v power going to the compass. I've also got pull up resistors wired in to the I2C lines at the compass.

Thanks for any help you can provide.

[Gerry]

Your code to restore factory calibration is not correct. You MUST send the 3 bytes in 3 separate transaction, not all in the same tranaction as you are doing.

Try somethin like this:
Wire.beginTransmission(deviceId);
Wire.write(22);
Wire.write(0x20);
Wire.endTransmission();
delay(100);
Wire.beginTransmission(deviceId);
Wire.write(22);
Wire.write(0x2A);
Wire.endTransmission();
delay(100);
Wire.beginTransmission(deviceId);
Wire.write(22);
Wire.write(0x60);
Wire.endTransmission();

[eclipsh]

Thanks, I tried that code and I'm still getting major heading changes when the compass is tilted. The serial print below is heading, pitch then roll.

Data received, value is: 656, 255, 1
Data received, value is: 656, 255, 1
Data received, value is: 650, 254, 1
Data received, value is: 588, 253, 1
Data received, value is: 630, 254, 1
Data received, value is: 485, 249, 0
Data received, value is: 434, 246, 0
Data received, value is: 380, 242, 0
Data received, value is: 371, 241, 255
Data received, value is: 379, 242, 0
Data received, value is: 385, 242, 0
Data received, value is: 383, 242, 0
Data received, value is: 388, 242, 0
Data received, value is: 388, 243, 0
Data received, value is: 390, 243, 06
Data received, value is: 390, 243, 0

As you can see, a 12 degree tilt results in a 26 degree heading change. Any thoughts on how to fix this?

[Gerry]

What Firmware version do you have?
(read from register 0).

[eclipsh]

Thanks for the response. I'm very new to coding for communications so I may have done this wrong.

I put in this code:

void loop(){
Wire.beginTransmission(deviceId);
Wire.requestFrom(deviceId, 0);
delay(10);
int avail = Wire.available();
unsigned int value = ((unsigned int)Wire.read()) << 8;
value = value + ((unsigned int)Wire.read());

Serial.print("Data received, value is: ");
Serial.println(value);

delay(1000);
}


and get a response of 65279

Is that correct?

[Gerry]

Your code is not correct.

From our Arduino example, try something like:

int soft_ver()
{
int data; // Software version of CMPS10 is read into data and then returned

Wire.beginTransmission(ADDRESS);
Wire.send(0); // Sends the register we wish to start reading from
Wire.endTransmission();

Wire.requestFrom(ADDRESS, 1); // Request byte from CMPS10
while(Wire.available() < 1);
data = Wire.receive();

return(data);
}

[eclipsh]

Thanks again for the help. It looks like I'm running version 4. I had to change the return command to a Serial.println to get a print out. Hopefully that didn't screw anything up.

For what it is worth, writing to 0 doesn't work in Arduino 1.0 software. I had to go back to 0022 to check this. Hopefully they'll fix that but someone else might have the same problem before then.

[Gerry]

I'm running version 4.

Thanks, there was a calibration issue with V4 that may explain your results.
Please contact support11@robot-electronics.co.uk

[c1p81]

i have the exact same problem with version 7
in flat position the bearing is quite ok (difference < 5° from a magnetic geological compass)
but tilting the pcb the data changes as i modify the roll and the pitch of PCB

[c1p81]

i have the same problem with version 7

L

[c1p81]

i think i have found the solution for my problem
the pcb is mounted up-side down on my breadboard
the right way is put the pin on the top

Luca