https://github.com/JChristensen/movingAvg
README file
Jack Christensen
Mar 2012
Arduino movingAvg Library Copyright (C) 2018 Jack Christensen GNU GPL v3.0
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License v3.0 as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/gpl.html
movingAvg is a simple Arduino library for calculating moving averages. It is useful for smoothing sensor readings, etc. For efficiency, the library operates in the integer domain. This means that the calculated moving averages are mathematically approximate. Both data input to the library and the returned moving averages are 16-bit signed integers.
The user specifies the interval (number of data points) for the moving average in the constructor. When the begin() function is called, an array is dynamically allocated to hold the number of data points in the interval. This array is never deallocated, and the user should call begin() only once (for a given movingAvg instance) in setup or other initialization code. Dynamic allocation is used strictly with the intent of creating the proper size array for the user's purposes, and not to free up the memory at a later point. It is strongly recommended that movingAvg objects remain allocated as long as the code is running. Failure to observe these guidelines can result in heap fragmentation, crashes and other undesired behavior.
Defines a movingAvg object where the average is calculated using interval data points.
movingAvg(interval);
interval: The number of data points to use when calculating the moving average. (int)
avoidDivByZero: Optional parameter that causes getAvg() (see caution below) to return zero if called before any readings are recorded. (bool, defaults to false if not given)
None.
movingAvg mySensor(10); // use 10 data points for the moving averageInitializes a movingAvg object. Call begin() once and only once for any given movingAvg instance. See comments in the Description section above.
begin();
None.
None.
movingAvg mySensor(10); // use 10 data points for the moving average
mySensor.begin();Adds a new data point to the moving average. Returns the new moving average value. Until the interval array is filled, the average is calculated from those data points already added, i.e. a fewer number of points than defined by the constructor - thanks to Tom H. (Duckie) for this idea!
reading(dataPoint);
dataPoint: The new data point to be added to the moving average. (int)
The new moving average value. (int)
int sensorData = analogRead(SENSOR_PIN);
int sensorMovingAvg = mySensor.reading(sensorData);Returns the current moving average value without adding a new reading.
Caution: If getAvg() is called before any data points (readings) are recorded, a divide-by-zero situation will occur, likely with unpredictable/undesirable results. To instead have getAvg() return a value of zero in this case, set the optional avoidDivByZero parameter in the constructor to true. Note that this may require the caller to implement additional logic to differentiate between a "no data" situation and one where the average is actually zero.
getAvg();
None.
The moving average value. (int)
int sensorMovingAvg = mySensor.getAvg();Like getAvg() except only uses the most recent nPoints data points to calculate the average. This allows calculation of shorter term and longer term averages. If nPoints is less than one, or larger than the number of points given in the constructor, or larger than the number of data points so far accumulated, then zero is returned.
getAvg(nPoints);
nPoints: The number of points to use to calculate a shorter-term average. (int)
The moving average value. (int)
int sensorMovingAvg = mySensor.getAvg(4);Returns the number of data points collected for the moving average, a number between zero and interval. This function can be used to determine if a valid moving average exists. This may be useful, for example, to avoid calling getAvg() before any data points have been added to the moving average. Calling getAvg() before any data points are added causes a divide by zero which will result in invalid data and/or undefined/undesired behavior.
getCount();
None.
The number of data points. (int)
int n = mySensor.getCount();Restarts the moving average. Zeros the interval array and associated data.
reset();
None.
None.
mySensor.reset();Returns a pointer to the integer array containing the collected data points.
getReadings();
None.
Pointer to an integer array. (int*)
movingAvg foo(6);
...
int* myData;
myData = foo.getReadings();
Serial.println(myData[0]); // first data point
Serial.println(myData[1]); // second data point
// etc.