1 files changed, 22 insertions, 0 deletions
diff --git a/src/components/heartrate/Biquad.h b/src/components/heartrate/Biquad.h
new file mode 100644
index 0000000..7c8ca58
--- /dev/null
+++ b/src/components/heartrate/Biquad.h
@@ -0,0 +1,22 @@
+#pragma once
+
+namespace Pinetime {
+  namespace Controllers {
+    /// Direct Form II Biquad Filter
+    class Biquad {
+    public:
+      Biquad(float b0, float b1, float b2, float a1, float a2);
+      float Step(float x);
+
+    private:
+      float b0;
+      float b1;
+      float b2;
+      float a1;
+      float a2;
+
+      float v1 = 0.0f;
+      float v2 = 0.0f;
+    };
+  }
+}