Loop Send 0x3D 0x06 Read all 6 bytes. However, a quick read of that article shows that the term degaussing also applies to the cancellation of the external fields resulting from magnetization of materials through the careful use of one or more coils excited by a DC current to “cancel” the field within some finite region. This function is enabled and the polarity is set by bits MS[n] in the configuration register A. Sign up using Facebook. This page was last edited on 6 November , at
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Sparkfun: HMCL Magnetometer –
Usually degaussing of macroscopic objects is done with an AC field that slowly decreases in amplitude. To check the HMCL for proper operation, a self test feature in incorporated in which the sensor is internally excited with a nominal magnetic field in either positive or negative bias configuration.
Thank you for taking the time to post this! Martin Bonfiore 86 1. I’d like to see a C code version working. 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.
If you don’t have an external event available to use as a warning sign of reduced performance, the common practice is to simply reset at regular intervals. Starting with the node.
The Other Things: HMCL magnetometer to Raspberry Pi connection notes
With power supply applied, the sensor converts any incident magnetic field in the sensitive axis directions to a differential voltage output. I’m asking specifically about 1 “Degaussing” and you’ve pasted a section on 2 “Self Test”.
If a constant or unequal external field is applied over time, eventually the “spring” will lose some restoring force tension. I assume it is the second kind that this function is designed for of course, not the first.
What I am now wondering how well the internal degauss function really works if the chip is exposed to very high fields and how long it takes how many read cycles to work assuming I correctly understand the operation. Else At least one axis did not pass positive self test. However, these straps are also said to work for degaussing, but I have still not found clear instructions how to use them to degauss the sensor.
Email Required, but never shown. Here is a related question I’ve also asked in Physics SE; What is actually happening when a magnetoresistive magnetometer degausses itself?
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. I have a hunch that the material used in the sensor is extremely susceptible to becoming magnetized.
Sparkfun: HMC5883L Magnetometer
Consider this magnet in a magnetic field: Here is an interesting clue! Thank you very much! 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 hmmc5883l is driving the control pins typ.
In the magneto-resistive device case, the equivalent is a shift in the lniux alignment vector. The procedures account for all 3 operations you mentioned. The amount of drift error that you consider tolerable is a function of your application how deep is your ADC noise floor, how error-tolerant are your algorithms, etc. The Beagle Bone can be connected to the magnetometer via the I2C bus.
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?
Hey this is great!! I think the manufacture should have chosen another term besides ‘degaussing’, which is misleading in this case.