Does anyone know if you can back bias the hall sensor particularly in the Z axis. There is an example in the Technical documentation that isn’t very good. I experimented on my own with a magnet and didn’t get any iron sensing result.
I have some generic advice that I found:
Magnet Placement
- Obtain a small, strong permanent magnet (e.g., a neodymium magnet).
- Position the magnet directly behind the TMAG5273 sensor chip, opposite the sensing side
Datasheet (refer to this several times for specs, figures, etc). The magnet should be aligned with the Z-axis of the sensor. - Ensure the magnet is fixed in a stationary position relative to the sensor…this creates the back-bias configuration.
Sensor Configuration
- Configure the TMAG5273 to use its Z-axis channel for sensing.
- Adjust the sensitivity range of the Z-axis channel to accommodate the magnetic field strength of your back-bias magnet. The TMAG5273 offers multiple sensitivity ranges
(https://www.ti.com/lit/ds/symlink/tmag5273.pdf) - Program the sensor’s settings, including the Z-axis configuration and sensitivity.
The TMAG5273 has built-in offset cancellation features. You’ll need to configure these to work with your back bias setup:
a. Use the Z_THR register (address 0x0F) to set the threshold for z-axis measurements.
b. Adjust the CONV_AVG register (address 0x09) to set the number of samples for averaging, which can help stabilize readings with the back bias applied.
Calibrate
- Perform a brief calibration routine to measure peak output values from the Z-axis
- Calculate the offset to subtract from each measurement using the formula:
Offset = (Outmax + Outmin) / 2 - Normalize the amplitude by dividing each output by the total amplitude
And that should get ya goin