EWA summarizer (in tests only).

dlyubimov · Jul 1, 2017 · 2a5cadd · 2a5cadd
1 parent c0a1696
commit 2a5cadd
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Showing 4 changed files with 79 additions and 5 deletions.
diff --git a/Hydra_EVSE/Hydra_EVSE.h b/Hydra_EVSE/Hydra_EVSE.h
@@ -34,7 +34,7 @@
 #define SW_VERSION "2.4.1-dev"
 
 // Define this for the basic unit tests run in a generica arduino uno board with a display shield.
-//#define UNIT_TESTS
+#define UNIT_TESTS
 
 #define UINT_BITS (sizeof(unsigned int) << 3)
 #define ULONG_BITS (sizeof(unsigned long) << 3)

diff --git a/Hydra_EVSE/Hydra_EVSE.ino b/Hydra_EVSE/Hydra_EVSE.ino
@@ -398,7 +398,7 @@ void displayStatus(unsigned int status)
   display.print(carLetter); // 1
   display.print(':');  // 2
 
-  logDebug(P("status: %x, CAR:%c, status bits: %x, status mask: %x."), status, carLetter, status & STATUS_MASK, STATUS_MASK);
+  logTrace(P("status: %x, CAR:%c, status bits: %x, status mask: %x."), status, carLetter, status & STATUS_MASK, STATUS_MASK);
 
   switch ( status & STATUS_MASK)   // 7
   {

diff --git a/Hydra_EVSE/onlineSum.h b/Hydra_EVSE/onlineSum.h
@@ -0,0 +1,44 @@
+
+// Exponentially Weighted Average summarizer
+// http://tdunning.blogspot.com/2011/03/exponentially-weighted-averaging-for.html
+// http://weatheringthrutechdays.blogspot.com/2011/04/follow-up-for-mean-summarizer-post.html
+
+// T is double or float
+template <class T>
+class EWASum {
+
+    T alpha;
+    T w, s, tn;
+
+  public:
+    // tHalfPeriod is amount of t after which the observation is exponentially weighed at 0.5 of the current observation.
+    EWASum(T tHalfPeriod) : alpha(-tHalfPeriod / log((T)0.5)) {
+      reset();
+    };
+
+    void reset() {
+      w = s = tn = 0;
+    }
+
+    void update(T x, T t);
+
+    // Evaluate EWA
+    T ewa();
+};
+
+template <class T>
+void EWASum<T>::update(T x, T t) {
+  T pi = exp(tn - t) / alpha;
+  s += pi * s + x;
+  w += pi * w + 1;
+  if (t > tn) tn = t;
+}
+
+template <class T>
+T EWASum<T>::ewa() {
+  return (w == 0) ? 0 : s / w;
+}
+
+// On arduino, double seems to be the same as float and take 4 bytes!
+typedef EWASum<double> EWASumD;
+typedef EWASum<float> EWASumF;
diff --git a/Hydra_EVSE/units.cpp b/Hydra_EVSE/units.cpp
@@ -21,6 +21,7 @@
 ///////////////////////////////////////////////////
 
 #include "Hydra_EVSE.h"
+#include "onlineSum.h"
 
 // If unit tests are declared, this is called the last thing from setup().
 
@@ -59,7 +60,7 @@ static void showDS(char* desc, unsigned int status) {
   display.clear();
   display.print (desc);
   displayStatus(status);
-  Delay(1000);
+  Delay(200);
 }
 
 void testDisplayStatus() {
@@ -95,8 +96,10 @@ void testDisplayStatus() {
   if ( cars[0].carLetter() != 'A' || cars[1].carLetter() != 'B' )
     logInfo(P("carLetter() UNIT FAIL"));
 
-  if ( cars[0].dispCol() != 0 || cars[1].dispCol() != 8 ) 
-    logInfo(P("dispCol() UNIT FAIL"));    
+  if ( cars[0].dispCol() != 0 || cars[1].dispCol() != 8 )
+    logInfo(P("dispCol() UNIT FAIL"));
+
+  logInfo (P("displayStatus DONE."));
 }
 
 
@@ -105,10 +108,37 @@ static void testMenuSetup() {
   doMenu(true);
 }
 
+static void testEWASumSetup() {
+  //  logInfo(P("sizeof(double)=%d"), sizeof(double));
+  //  logInfo(P("sizeof(float)=%d"), sizeof(float));
+
+  EWASumD sum(100);
+
+  boolean fail = false;
+  sum.update(5, 1000);
+  if ( abs(sum.ewa() - 5.0) > 1e-10) fail = true;
+
+    sum.update(10, 1100);
+  if ( abs(sum.ewa() - 7.5) > 1e-10) fail = true;
+
+  // update-in-the-past test.
+  sum.reset();
+
+  sum.update(10, 1100);
+  if ( abs(sum.ewa() - 10) > 1e-10) fail = true;
+
+  sum.update(5, 1000);
+  if ( abs(sum.ewa() - 7.5) > 1e-10) fail = true;
+
+  if ( fail) logInfo(P("EWASum UNIT FAIL"));
+  else logInfo(P("EWASum DONE."));
+}
+
 
 int unitsSetup() {
 
   testEepromSetup();
+  testEWASumSetup();
   testDisplayStatus();
   testMenuSetup();
   return false;