Support for I2C device HMC5883L (3-axis magnetic sensor)

[AndreasAchtzehn]

Description:

Support for HMC5883L 3-axis magnetic sensor.
Tested with GY-271.

Configuration:
Sensor101 GAIN,x // sensor gain
Sensor101 RATE,x // data acquisition rate for continuous mode, activate continuous mode by manually setting HMC5883L->mode = HMC5883L_MODE_CONT in xsns_101_hmc5883l.ino
Sensor101 AVG,x // 2^X number of samples to average over
Sensor101 MMODE,x // measurement mode (normal, positive, negative bias)

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.5
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[barbudor]

Isn't it possible to merge with QMC5883 driver ?
https://github.com/arendst/Tasmota/blob/development/tasmota/tasmota_xsns_sensor/xsns_33_qmc5883l.ino

Or may be the chips are too different despite the naming ?

[AndreasAchtzehn]

I was originally hoping to use/slightly adapt the QMC5883L driver for my HMC5883L device (GY-271). After review of the data sheets and tinkering with the original driver I ended up in doing the new implementation. The devices differ in such subtle points as the LSB/MSB register order, HMC5883L further lacks the temperature support, but ultimately they feature a largely different configuration register organization. So, unfortunately no, there is no easy way to use the same driver for both devices.

[sugus6]

Thank you for the HMC5883L support. I got my pcb running.
Is it possible to add the "Compass Heading" to the Tasmota UI?