Added hacky heading function to magnetometer example, next version should be refactored and based on https://gist.github.com/CalebFenton/a97444750eb43e3354fd2d0196a2ebcf

Author: aiunderstand

boards/MicroBit_v2/src/full/microbit-accelerometer.adb

@@ -28,9 +28,9 @@
 --   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.   --
 --                                                                          --
 ------------------------------------------------------------------------------
-
 with MicroBit.I2C;
-
+with Ada.Numerics; use Ada.Numerics;
+with Ada.Numerics.Generic_Elementary_Functions;
 package body MicroBit.Accelerometer is
 
    Acc  : LSM303AGR.LSM303AGR_Accelerometer (MicroBit.I2C.Controller);
@@ -47,7 +47,7 @@ package body MicroBit.Accelerometer is
          MicroBit.I2C.Initialize;
       end if;
 
-      Acc.Configure (LSM303AGR.Freq_400, LSM303AGR.Freq_10, LSM303AGR.Continuous_Mode);
+      Acc.Configure (LSM303AGR.Freq_400, LSM303AGR.Freq_100, LSM303AGR.Continuous_Mode);
    end Initialize;
 
    ----------
@@ -63,6 +63,48 @@ package body MicroBit.Accelerometer is
    function MagData return LSM303AGR.All_Axes_Data
    is (Acc.Read_Magnetometer);
 
+   --Based on https://rosettacode.org/wiki/Map_range#Ada
+   function Map ( Value : Float;
+                  A1 : Float; -- Range Min (from)
+                  A2 : Float; -- Range Max (from)
+                  B1 : Float; -- Range Min (to)
+                  B2 : Float -- Range Max (to)
+                ) return Float is
+   begin
+      return B1 + (Value - A1) * (B2 - B1) / (A2 - A1);
+   end Map;
+
+   function Heading return LSM303AGR.Angle is
+      package test is new Generic_Elementary_Functions (Float_Type => Float);
+      Data : LSM303AGR.All_Axes_Data;
+      Result: Float;
+      X : Float;
+      Y : Float;
+      Z : Float;
+      Angle : Integer;
+   begin
+      --get raw sensor data
+      Data := MagData;
+      X := Float (Data.X);
+      Y := Float (Data.Y);
+      Z := Float (Data.Z);
+
+      --map to known ranges using calibrated values (or 0 for using factory default)
+      --it is up to the programmer to call calibrate first (although recommended)
+      X := Map(X, MagMinX, MagMaxX, -1023.0, 1023.0);
+      Y := Map(Y, MagMinY, MagMaxY, -1023.0, 1023.0);
+      Z := Map(Z, MagMinZ, MagMaxZ, 0.0, 1023.0);
+
+      --calc angle
+      Result := (Test.Arctan(Y, X) * 180.0) / Pi;
+      Result := Result + 90.0;
+
+      --normalize such we can cast to Angle.
+      Angle := Integer(Result) mod 360;
+
+      return LSM303AGR.Angle(Angle);
+   end Heading;
+
 begin
    Initialize;
 end MicroBit.Accelerometer;

boards/MicroBit_v2/src/full/microbit-accelerometer.ads

@@ -32,6 +32,13 @@
 with LSM303AGR;
 
 package MicroBit.Accelerometer is
+   MagMinX : Float := -1.0 ; -- -32767.0;
+   MagMinY : Float := -6.0 ; -- -32767.0;
+   MagMinZ : Float := -8.0;    --  -32767.0;
+
+   MagMaxX : Float :=  11.0 ; -- 32767.0;
+   MagMaxY : Float :=  7.0; -- 32767.0;
+   MagMaxZ : Float :=  4.0; -- 32767.0;
 
    function AccelDataRaw return LSM303AGR.All_Axes_Data_Raw;
 
@@ -41,4 +48,14 @@ package MicroBit.Accelerometer is
    function MagData return LSM303AGR.All_Axes_Data;
    --  Return the magneto value for each of the three axes (X, Y, Z)
 
+   function Map ( Value : Float;
+                  A1 : Float; -- Range Min (from)
+                  A2 : Float; -- Range Max (from)
+                  B1 : Float; -- Range Min (to)
+                  B2 : Float -- Range Max (to)
+                ) return Float;
+   -- Return mapped value
+
+   function Heading return LSM303AGR.Angle;
+   -- Return the heading based on the magnetometer
 end MicroBit.Accelerometer;

components/src/motion/lsm303agr/lsm303agr.ads

@@ -54,6 +54,7 @@ package LSM303AGR is
    type Axis_Data is range -2**9 .. 2**9 - 1 with Size => 10; -- we decimate from 16 (the output of the accel device) to 10 bits? Why?
                                                               -- Does this mean that the actual range is -512 .. 511?
 
+   type Angle is range 0 .. 360;
    type Axis_Data_Raw is record
       Low : UInt8;
       High : UInt8;

examples/MicroBit_v2/ravenscar/accelerometer/.vscode/settings.json

@@ -1,3 +1,4 @@
 {
     "cortex-debug.armToolchainPrefix": "arm-eabi"
+	"sarif-viewer.connectToGithubCodeScanning": "off"
 }

examples/MicroBit_v2/ravenscar/magnetometer/src/main.adb

@@ -5,14 +5,46 @@ use MicroBit;
 procedure Main is
 
     Data: All_Axes_Data;
+    Heading : Angle;
+    MinX, MinY, MinZ, MaxX, MaxY, MaxZ : Axis_Data := 0;
 begin
    loop
     Data := Accelerometer.MagData;
-    Put_Line ("MAG;" &
-                "X,"  & Data.X'Img & ";" &
-                "Y,"  & Data.Y'Img & ";" &
-                "Z,"  & Data.Z'Img);
 
+    if Data.X < MinX then
+      MinX := Data.X;
+    end if;
+
+    if Data.Y < MinY then
+      MinY := Data.Y;
+end if;
+
+    if Data.Z < MinZ then
+      MinZ := Data.Z;
+end if;
+
+   if Data.X > MaxX then
+      MaxX := Data.X;
+      end if;
+
+   if Data.Y > MaxY then
+      MaxY := Data.Y;
+      end if;
+
+   if Data.Z > MaxZ then
+      MaxZ := Data.Z;
+      end if;
+
+    Put_Line ("MIN X Y Z;" & MinX'Img & MinY'Img & MinZ'Img);
+    Put_Line ("MAX X Y Z;" & MaxX'Img & MaxY'Img & MaxZ'Img);
+
+   --   Put_Line ("MAG;" &
+   --               "X,"  & Data.X'Img & ";" &
+   --               "Y,"  & Data.Y'Img & ";" &
+   --               "Z,"  & Data.Z'Img);
+
+    Heading := AcceleroMeter.Heading;
+         Put_Line("Heading;" & Heading'Img);
     delay 0.5;
    end loop;
 end Main;