Getting extreme readings

[mikevanis]

Hi @sparkfun,

I'm using this module with an ESP-12 and I'm just running the Basic example. I'm getting very unusual readings. Here is a typical sample:

X: 64895, Y: 425, Z: 64768

What could this be? Have I got a damaged MAG3110? Is there a weird scale value register set somewhere? Any clues would be much appreciated.

EDIT: Upon further investigation - the MAG3110 has two 8-bit registers for each axis. In this library, they're joined and packaged into an int. Shouldn't they be packed into a uint16_t or an unsigned int? Surely there's no sign in the values the magnetometer will spit out. Could I be getting these values due to an overflow?

[ejosh]

After digging slightly more into the solution for your issue submitted on this other repo, this should definitely use the signed int16_t, the sensor datasheet at one point refers to returning values from -30,000 to +30,000 for each axis. (Section 5.1.2, p.17)

[sanyi]

Here we can only cast x = (int) values[0]; if we are sure int has the same bite size as (in our specific case) 16. Obviously this is not the case so the sign bit is misinterpreted as 2^15. However being explicit x = (int16_t) values[0]; does the trick.

[DiscoMan18]

This library perfectly works on ESP32 devices. I checked it. Just change int to int16_t everywhere in the code.