Fixed some math bugs in the compass calcs, needle is now more accurate.

independent_logic/src/heading_drawing.rs

@@ -1,19 +1,22 @@
 use libm::{cosf, roundf, sinf};
 
 use crate::line_drawing::{draw_line, FourQuadrantMatrix, Line, Point};
+use crate::tilt_compensation::Heading;
 
-fn heading_to_line(heading: f32, square_size: usize) -> Line {
+fn heading_to_line(heading: Heading, square_size: usize) -> Line {
     Line(
         Point { x: 0, y: 0 },
         Point {
-            x: roundf((square_size as f32) * sinf(heading)) as isize,
-            y: roundf((square_size as f32) * cosf(heading)) as isize,
+            x: roundf((square_size as f32) * sinf(heading.0)) as isize,
+            y: roundf((square_size as f32) * cosf(heading.0)) as isize,
         },
     )
 }
 
-pub fn draw_heading<const X: usize, const Y: usize>(
-    heading: f32,
+// given the compass heading that the board '0' is facing,
+// draws a line always pointing towards heading 0
+pub fn draw_constant_heading<const X: usize, const Y: usize>(
+    heading: Heading,
     matrix: &mut FourQuadrantMatrix<{ X }, { Y }, u8>,
 ) {
     draw_line::<X, Y>(&heading_to_line(heading, X.min(Y)), matrix);

independent_logic/src/tilt_compensation.rs

@@ -18,6 +18,7 @@ pub struct Heading(pub f32);
 
 pub fn calc_attitude(measurement: &NedMeasurement) -> Attitude {
     //based off of: https://www.nxp.com/docs/en/application-note/AN4248.pdf
+    //Gp{xyz} is the acellerometer measurements.
     let roll = atan2f(measurement.y, measurement.z);
     let pitch = atanf(-measurement.x / (measurement.y * sinf(roll) + measurement.z * cosf(roll)));
     Attitude { pitch, roll }
@@ -28,23 +29,30 @@ pub fn calc_tilt_calibrated_measurement(
     attitde: &Attitude,
 ) -> NedMeasurement {
     //based off of: https://www.nxp.com/docs/en/application-note/AN4248.pdf
-
-    let corrected_mag_y =
-        mag_measurement.z * sinf(attitde.roll) - mag_measurement.y * cosf(attitde.roll);
+    // ø=roll,
+    // θ=pitch,
+    // Bp{xyz} is magnometer readings,
+    // V{xyz} is the magnometers constant hard-iron compnent, (currently taken care by micro:bits
+    // library)
 
     let corrected_mag_x = mag_measurement.x * cosf(attitde.pitch)
         + mag_measurement.y * sinf(attitde.pitch) * sinf(attitde.roll)
         + mag_measurement.z * sinf(attitde.pitch) * cosf(attitde.roll);
+    let corrected_mag_y =
+        mag_measurement.y * cosf(attitde.roll) - mag_measurement.z * sinf(attitde.roll);
+    let corrected_mag_z = -mag_measurement.x * sinf(attitde.pitch)
+        + mag_measurement.y * cosf(attitde.pitch) * sinf(attitde.roll)
+        + mag_measurement.z * cosf(attitde.pitch) * cosf(attitde.roll);
 
     NedMeasurement {
         x: corrected_mag_x,
         y: corrected_mag_y,
-        z: 0.0,
+        z: corrected_mag_z,
     }
 }
 
 //0 is the top sector and positive is clockwise, negative is counterclockwise.
-pub fn heading_from_measurement(measurement: NedMeasurement) -> Heading {
+pub fn heading_from_measurement(measurement: &NedMeasurement) -> Heading {
     Heading(atan2f(-measurement.y, measurement.x))
 }