Magnetic sensor

[Rubycon]

On smart phones such as the Samsung Galaxy S3, etc. what kind of sensor do they use for sensing magnetic fields? I have a metal detector app that reads in micro Tesla (µT) and was wondering if there is any kind of linearity to it. Using a very small neo source it's easy to find the sensor location in the device.

 

[pm]

The iPhone 3GS/4/4S/5 and the Samsung S3 all use an Asahi Kasei Microsystems AK8973 or AK8975 which is a 3-axis hall effect sensor.
http://www.droid-developers.org/images/b/b2/AK8973.pdf

It looks like you can adjust the gain and the DAC offset - although there's a big warning at the top of section 9.1 telling you not to change the values... it's funny to see a big explanation at 9.2.2 on how to do a write, a few pages after a huge bold and underlined statement saying to never write anything. But it seems like you do a write to MS1 at register address E0 to set it to write access and then change the values in E1-E6 to adjust the gain and the offset. Using this, you should be able to calibrate it for whatever you want, and then just write the original values back when you are done and want to undo everything to make it a compass again.

 

[Rubycon]

Thanks for that link!
I figured it was a hall effect sensor.