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libraries/ACS712/examples/estimateMidPointAC/estimateMidPointAC.ino

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+//    FILE: estimateMidPointAC.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: experimental 
+//     URL: https://github.com/RobTillaart/ACS712/issues/37
+//
+//  Estimates the midpoint by taking many (short-blocking) samples
+//  instead of many samples in a long blocking period.
+//  The function adjusts the confidence (or quality) of the midpoint 
+//  depending on the value read.
+//  This code is experimental and meant to investigate a non-blocking
+//  way to find the midPoint for the ACS712 when measuring AC currents.
+//
+//  It will not be included in the library
+//
+//  Use with care.
+
+
+#include "Arduino.h"
+
+
+uint32_t start, stop;
+int _pin = A0;
+uint32_t count = 0;
+volatile uint16_t mp;
+float conf = 0;
+
+
+uint16_t estimateMidPointAC(float &confidence, bool reset = false)
+{
+  static bool _firstCall = true;
+  static float _minimum, _maximum, _confidence;
+
+  int value = analogRead(_pin);
+  if (_firstCall || reset)
+  {
+    _firstCall = false;
+    _minimum = _maximum = value;
+    _confidence = 0;
+    confidence = _confidence;
+    return _minimum;
+  }
+  if (value > _maximum)
+  {
+    _maximum = value;
+    _confidence /= 2;
+  }
+  else if (value < _minimum)
+  {
+    _minimum = value;
+    _confidence /= 2;
+  }
+  else if (_confidence < 100)
+  {
+    _confidence += 1;
+  }
+  confidence = _confidence;
+  return (_minimum + _maximum) / 2;
+}
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial);
+  Serial.println(__FILE__);
+}
+
+
+void loop()
+{
+  count++;
+  start = micros();
+  mp = estimateMidPointAC(conf, true);
+  stop = micros();
+  Serial.print(millis());
+  Serial.print("\t");
+  Serial.print(count);
+  Serial.print("\t");
+  Serial.print(conf);
+  Serial.print("\t");
+  Serial.print(mp);
+  Serial.print("\t");
+  Serial.print(stop - start);
+  Serial.println();
+  delay(random(100));
+}
+
+
+//  -- END OF FILE --