We are working on a wireless device for parking detection using MAG3110. We are now in communication with manufacturers to plan for mass manufacturing our product. We have some concerns regarding test and calibration process which need to be done at our manufacturer's facility.
1) PCBA Testing
When we are doing small scale testing with MAG3110, we realized multiple magnetometer faults (many of this are due to soldering process)
Some of the faults are:
- MAG3110 make i2c bus hanged. (SDA or SCL stays at HIGH sometime)
- MAG3110 does not provide measurement after triggered. We used a one-shot trigger method with polling for DR_STATUS register.
- Leak current (some can go up to 100uA during idle)
- Some sensors report much higher raw x, y, z than the rest (i.e 10000 units). The gain of these sensors are not as good as other normal unit (x,y,z < 3000 units). FYI, we are located in Singapore.
We would like to get some advice on some technique to test MAG3110 after PCB Assembly. This will be very crucial for feasibility of using MAG3110 in production.
2) Calibration Process
2.1) We realized each of MAG3110 have a different offset value. When we assembled multiple PCBs and put at same location with minor change from environment, each sensor report different x, y, z value raw (no user offset). Usually what we do is to do a 3D rotation to all different possible orientation and get the centroid of the ellipsoid as our offset value. After offsetting that value, all our sensors report same x,y,z.
Is this behavior expected or is it due to our soldering fault?
2.2) We use changes in magnetic field for our detection. Hence, gain of x,y,z axis is very critical to us. Would there be a consistent way to test this after PCBA?
3) How do you guys test MAG3110 from the factory to ensure they are functional? It would be great if you can share a little more on that so we can try to do some similar test after our PCBA