BN-880 GPS/Compass Module With Arduino Uno - The Compass

So, I had a question posed to me: how accurate is the compass portion of the BN-880 module?
Answer: I don't know.
But let's try and find out.

Original post: https://rumble.com/vsxkbw-bn-880-gpscompass-module-with-arduino-uno.html

Blog (with wiring diagram) is here:

http://cat-walker.blogspot.com/2022/01/beitian-bn-880-gps-and-compass-module.html

Code is here:
https://cat-walker.blogspot.com/2023/05/bn-880-gpscompass-module-compass.html

Library for the Arduino is here:
https://github.com/sleemanj/HMC5883L_Simple

Adafruit HMC5883L Breakout Module:
https://www.adafruit.com/product/1746

HMC5883L Datasheet:
https://www.digikey.ca/en/htmldatasheets/production/786600/0/0/1/asd2613-r.html

Music by Axcel Shoo & The Garage Band Grease Nipples.