Added comments to each section of code

I was finding it hard to understand the code, so I worked it out and added lots of comments that should make the process quicker for others.

Author: KevWal

examples/magnetometer.py

@@ -16,37 +16,61 @@
 Y = 1
 Z = 2
 
+# The two axes which relate to heading, depends on orientation of the sensor
+# Think Left & Right, Forwards and Back, ignoring Up and Down
 AXES = Y, Z
 
+# Initialise the imu
 imu = ICM20948()
 
+# Store an initial two readings from the Magnetometer
 amin = list(imu.read_magnetometer_data())
 amax = list(imu.read_magnetometer_data())
 
 while True:
+    # Read the current, uncalibrated, X, Y & Z magnetic values from the magnetometer and save as a list
     mag = list(imu.read_magnetometer_data())
+    
+    # Step through each uncalibrated X, Y & Z magnetic value and calibrate them the best we can
     for i in range(3):
         v = mag[i]
+        # If our current reading (mag) is less than our stored minimum reading (amin), then save a new minimum reading
+        # ie save a new lowest possible value for our calibration of this axis
         if v < amin[i]:
             amin[i] = v
+        # If our current reading (mag) is greater than our stored maximum reading (amax), then save a new maximum reading
+        # ie save a new highest possible value for our calibration of this axis
         if v > amax[i]:
             amax[i] = v
+        
+        # Calibrate value by removing any offset when compared to the lowest reading seen for this axes
         mag[i] -= amin[i]
+        
+        # Scale value based on the higest range of values seen for this axes
+        # Creates a calibrated value between 0 and 1 representing magnetic value
         try:
             mag[i] /= amax[i] - amin[i]
         except ZeroDivisionError:
             pass
+        # Shift magnetic values to between -0.5 and 0.5 to enable the trig to work
         mag[i] -= 0.5
 
+    # Convert from Gauss values in the appropriate 2 axis to a heading in Radians using trig
+    # Note this does not compensate for tilt
     heading = math.atan2(
             mag[AXES[0]],
             mag[AXES[1]])
 
+    # If heading is negative, convert to positive, 2 x pi is a full circle in Radians
     if heading < 0:
         heading += 2 * math.pi
+        
+    # Convert heading from Radians to Degrees
     heading = math.degrees(heading)
+    # Round heading to nearest full degree
     heading = round(heading)
 
+    # Note: Headings will not be correct until a full 360 deg calibration turn has been completed to generate amin and amax data
     print("Heading: {}".format(heading))
 
     time.sleep(0.1)