lambda conversion

firmware/lambda_conversion.cpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "sampling.h"
+
+static float GetPhi(float pumpCurrent)
+{
+    // This estimation is accurate within 0.5% from 0.8 to 1.0, and 0.01% from 1 to 1.2 lambda when compared to the lookup table in the Bosch datasheet
+    float gain = pumpCurrent > 0 ? -0.28299f : -0.44817f;
+
+    return gain * pumpCurrent + 0.99559f;
+}
+
+float GetLambda()
+{
+    float pumpCurrent = GetPumpNominalCurrent();
+
+    // Lambda is reciprocal of phi
+    return 1 / GetPhi(pumpCurrent);
+}