FINALLY!!!!
the issue was:
inside the GY-87 the HMC is in a different I2C bus? which has to be enabled, otherwise, the MPU wont be able to read anything from it....
I added this code to my 'void setup' being accelgyro the MPU object:
accelgyro.setI2CBypassEnabled(true);
After this, I don't get a very real value of the heading, but.... at least I get something: ACCESS TO THE HMC5883L!!!!!!
I'll continue posting with the solution to a correct heading indication.... some math to do....
cheers!!!
