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The rate at which the sensor drifts loses sensitivity or adds offset is a function of the environment how strong and unbalanced are the external fields. This is quoted directly from the datasheet you posted. Then point you web browser to bone: Datasheets don’t include answers to these questions because they are application-specific. To fix this, degaussing coils are present to provide a strong local impulse momentary force to remove any of these external influences and reset liunx magnetic domain to its original alignment, thus recalibrating the transducer.
A change in the measurement before and during this field offset can be used to confirm that umc5883l device is functional, as a manufacturing test. If it is meant to somehow cancel or ilnux for another arbitrary field, the current would have to be continuously variable and include both signs, and I don’t see that here. In the magneto-resistive device case, the equivalent is a shift in the magnetic alignment vector.
It’s either on or off. It is not related to demagnetization in any way.
CONFIG_SENSORS_HMC5843_I2C: Honeywell HMC5843/5883/5883L 3-Axis Magnetometer (I2C)
Are there actually coils inside the chip that are intended to carry DC currents to cancel some fields? It also appears though less clear from the data sheet that the sensor is “pulsed” then read and then “reset pulsed” and read again and the two reads are subtracted to account for residual magnetism and temperature drift.
I’m asking specifically about 1 “Degaussing” and you’ve pasted a section on 2 “Self Test”. I’m asking about something that is not explained in the PDF. Takes one measurement M1 3. That is a nice big color vote-attracting picture though: Automatic and manual degaussing magnetic heads on tape recorders and magnetic shielding on CRTs are some examples. This page was last edited on 6 Novemberat To implement self test, the least significant bits MS1 and MS0 of configuration register A are changed from 00 to 01 positive bias or 10 negetive bias.
That is why you could not find a section on “Degaussing”, as it is part of these calibration procedures.
I think spending the first two paragraphs explaining this in the question anticipating this confusion and then patiently reiterating this several times in the comments is very nice of me. Send 0x3C 0x03 point to first data register 03 Wait about 67 ms if 15 Hz rate or monitor status register or DRDY hardware interrupt pin.
There is often an internal amplifier in the part between the control pin s and the actual coil s so that the inputs may safely remain high impedance and not pull too much current from whatever is driving the control pins typ. I think it makes it a good question. Starting with the node.
The degaussing maybe nothing more than an offset null for the internal ADC, or bias currents for the sensor cell. I didn’t ask what is degaussing or why is it necessary, I asked specifically ” How is the degaussing feature in the HMCL 3-Axis Digital Compass chip correctly used? I think you are asking about the first kind. This current is sourced from an external capacitor nominally 0. However, like the mechanical spring, the long term consistent exposure results in a gradual realignment of the origin domain and sensor stops being able to detect the external field as being different from it’s reference “original” one.
Degauss operations have a high energy and interference EMC cost.
The Other Things: HMCL magnetometer to Raspberry Pi connection notes
Self Test To check the HMCL for proper operation, a self test feature in incorporated in which the sensor is internally excited with a nominal magnetic liinux in either positive or negative bias configuration. Email Required, but never shown.
I think a few more people will up-vote as well, bringing you to reputation so you can start leaving comments. Your answer might also be helpful there, but I’m looking for specifics!