fix #26 DC measurements (#28)

* fix #26 midPoint data type
* fix incrMidpoint

.arduino-ci.yml

@@ -24,4 +24,5 @@ compile:
     - esp32
     - esp8266
     # - mega2560
-    - rpipico
+    - rpipico
+

ACS712.cpp

@@ -1,49 +1,9 @@
 //
 //    FILE: ACS712.cpp
 //  AUTHOR: Rob Tillaart, Pete Thompson
-// VERSION: 0.3.1
+// VERSION: 0.3.2
 //    DATE: 2020-08-02
 // PURPOSE: ACS712 library - current measurement
-//
-//  HISTORY:
-//  0.1.0  2020-03-17  initial version
-//  0.1.1  2020-03-18  first release version
-//  0.1.2  2020-03-21  automatic form factor test
-//  0.1.3  2020-05-27  fix library.json
-//  0.1.4  2020-08-02  Allow for faster processors
-//
-//  0.2.0  2020-08-02  Add autoMidPoint
-//  0.2.1  2020-12-06  Add Arduino-CI + readme + unit test + refactor
-//  0.2.2  2021-06-23  support for more frequencies.
-//  0.2.3  2021-10-15  changed frequencies to float, for optimal tuning.
-//                     updated build CI, readme.md
-//  0.2.4  2021-11-22  add experimental detectFrequency()
-//  0.2.5  2021-12-03  add timeout to detectFrequency()
-//  0.2.6  2021-12-09  update readme.md + license
-//  0.2.7  2022-08-10  change mVperAmp to float
-//                     add ACS712_FF_SAWTOOTH
-//                     update readme.md + unit test + minor edits
-//  0.2.8  2022-08-19  prepare for 0.3.0
-//                     Fix #21 FormFactor
-//                     add mA_AC_sampling() as method to determine
-//                     current when FormFactor is unknown.
-//                     added float _AmperePerStep cached value.
-//                     added getAmperePerStep();
-//                     moved several functions to .cpp
-//                     improve documentation
-//
-//  0.3.0  2022-09-01  return midPoint value in MP functions.
-//                     float return type for mA() functions
-//                     add float mA_peak2peak(freq, cycles)
-//                     add debug getMinimum(), getmaximum();
-//                     update Readme.md
-//  0.3.1  2022-09-xx  add float mVNoiseLevel(frequency, cycles)
-//                     add void suppressNoise(bool flag) 
-//                         experimental suppression by averaging two samples.
-//                     update readme.md
-//                     improve midPoint functions
-//                     add resetMidPoint()
-//                     add RP2040 pico in build-ci
 
 
 #include "ACS712.h"
@@ -184,6 +144,7 @@ float ACS712::mA_AC_sampling(float frequency, uint16_t cycles)
       }
       float current = value - _midPoint;
       sumSquared += (current * current);
+      // not adding noise squared might be more correct for small currents.
       // if (abs(current) > noiseLevel)
       // {
       //   sumSquared += (current * current);
@@ -223,7 +184,7 @@ float ACS712::mA_DC(uint16_t cycles)
 //  CALIBRATION MIDPOINT
 uint16_t ACS712::setMidPoint(uint16_t midPoint)
 {
-  if (midPoint <= _maxADC) _midPoint = midPoint;
+  if (midPoint <= _maxADC) _midPoint = (int) midPoint;
   return _midPoint;
 };
 
@@ -236,7 +197,7 @@ uint16_t ACS712::getMidPoint()
 
 uint16_t ACS712::incMidPoint()
 {
-  if (_midPoint < _maxADC) _midPoint += 1;
+  if (_midPoint < (int)(_maxADC)) _midPoint += 1;
   return _midPoint;
 };
 

ACS712.h

@@ -2,7 +2,7 @@
 //
 //    FILE: ACS712.h
 //  AUTHOR: Rob Tillaart, Pete Thompson
-// VERSION: 0.3.1
+// VERSION: 0.3.2
 //    DATE: 2020-08-02
 // PURPOSE: ACS712 library - current measurement
 //
@@ -12,7 +12,7 @@
 
 #include "Arduino.h"
 
-#define ACS712_LIB_VERSION        (F("0.3.1"))
+#define ACS712_LIB_VERSION        (F("0.3.2"))
 
 
 //  ACS712_FF_SINUS == 1.0/sqrt(2) == 0.5 * sqrt(2)
@@ -111,7 +111,7 @@ class ACS712
     float     _formFactor;    //  peak2peak -> RMS
     float     _mVperAmpere;
     float     _mAPerStep;
-    uint16_t  _midPoint;
+    int       _midPoint;
     uint8_t   _noisemV;
     float     _microsAdjust   = 1.0;  //  0.9986
     bool      _suppresNoise = false;

CHANGELOG.md

@@ -0,0 +1,88 @@
+# Change Log AD520X
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+
+## [0.3.2] - 2022-11-18
+- fix #26 revert data type \_midPoint to int
+- Add CHANGELOG.md
+
+## [0.3.1  2022-09-xx  
+- add float mVNoiseLevel(frequency, cycles)
+- add void suppressNoise(bool flag) - experimental suppression by averaging two samples.
+- update readme.md
+- improve midPoint functions
+- add resetMidPoint()
+- add RP2040 pico in build-ci
+
+## [0.3.0] - 2022-09-01
+- return midPoint value in MP functions.
+- float return type for mA() functions
+- add float mA_peak2peak(freq, cycles)
+- add debug getMinimum(), getmaximum();
+- update Readme.md
+
+----
+
+## [0.2.8] - 2022-08-19  prepare for 0.3.0
+- Fix #21 FormFactor
+- add mA_AC_sampling() as method to determine
+- current when FormFactor is unknown.
+- added float _AmperePerStep cached value.
+- added getAmperePerStep();
+- moved several functions to .cpp
+- improve documentation
+
+## [0.2.7] - 2022-08-10
+- change mVperAmp to float
+- add ACS712_FF_SAWTOOTH
+- update readme.md + unit test + minor edits
+
+## [0.2.6] - 2021-12-09
+- update readme.md
+- update license
+
+## [0.2.5] - 2021-12-03
+- add timeout to detectFrequency()
+
+## [0.2.4] - 2021-11-22
+- add experimental detectFrequency()
+
+## [0.2.3] - 2021-10-15
+- change frequencies to float, for optimal tuning.
+- update build CI
+- update readme.md
+
+## [0.2.2] - 2021-06-23
+- support for more frequencies
+
+## [0.2.1] - 2020-12-06
+- Add Arduino-CI + unit test
+- update readme 
+- refactor
+
+## [0.2.0] - 2020-08-02
+- Add autoMidPoint()
+
+----
+
+## [0.1.4] - 2020-08-02
+- Allow for faster processors
+
+## [0.1.3] - 2020-05-27
+- fix library.json
+
+## [0.1.2] - 2020-03-21
+- automatic form factor test
+
+## [0.1.1] - 2020-03-18
+- first release version
+
+## [0.1.0] - 2020-03-17
+- initial version
+
+
+

README.md

@@ -147,10 +147,10 @@ The midpoint is the (raw) zero-reference for all current measurements.
 It is defined in steps of the ADC and is typical around half the **maxADC** value defined 
 in the constructor. So for a 10 bit ADC a number between 500..525 is most likely.
 
-Since 0.3.0 all midpoint functions return actual midPoint.
+Since 0.3.0 all midpoint functions return the actual midPoint.
 
 - **uint16_t setMidPoint(uint16_t midPoint)** sets midpoint for the ADC conversion.
-Parameter must be between 0 and maxADC, otherwise midpoint is not changed.
+Parameter must be between 0 and maxADC/2, otherwise midpoint is not changed.
 - **uint16_t autoMidPoint(float frequency = 50, uint16_t cycles = 1)** Auto midPoint, 
 assuming zero DC current or any AC current. 
 The function takes the average of many measurements during one or more full cycles.
@@ -176,7 +176,7 @@ One can use the two debug functions.
 and take the average of these two values. In code:
 
 ```cpp
-uint16_t midpnt = ACS.setMidPoint((ACS.getMinimum(20) + ACS.getMaximum(20)) / 2);
+uint16_t midpoint = ACS.setMidPoint(ACS.getMinimum(20)/2 + ACS.getMaximum(20)/ 2);
 ```
 See - ACS712_20_AC_midPoint_compare.ino
 
@@ -343,7 +343,7 @@ The examples show the basic working of the functions.
 #### Should - 0.3.x
 
 - investigate noise suppression  #21 (0.3.1 and later)
-- external history file = changelog.md
+- add external history file = changelog.md
 
 
 #### Could

library.json

@@ -21,7 +21,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/ACS712.git"
   },
-  "version": "0.3.1",
+  "version": "0.3.2",
   "license": "MIT",
   "frameworks": "arduino",
   "platforms": "*",

library.properties

@@ -1,5 +1,5 @@
 name=ACS712
-version=0.3.1
+version=0.3.2
 author=Rob Tillaart <[email protected]>, Pete Thompson <[email protected]>
 maintainer=Rob Tillaart <[email protected]>
 sentence=ACS712 library for Arduino.

test/unit_test_001.cpp

@@ -123,6 +123,10 @@ unittest(test_midPoint)
   amp = ACS.getMidPoint();
   assertEqual(1000, amp);
 
+  ACS.decMidPoint();
+  amp = ACS.getMidPoint();
+  assertEqual(999, amp);
+
   ACS.resetMidPoint();
   amp = ACS.getMidPoint();
   assertEqual(511, amp);