Diff: MAX30100_Filters.h

Revision:

0:010b908e2187

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MAX30100_Filters.h	Fri Nov 25 00:52:54 2016 +0000
@@ -0,0 +1,71 @@
+/*
+Arduino-MAX30100 oximetry / heart rate integrated sensor library
+Copyright (C) 2016  OXullo Intersecans <x@brainrapers.org>
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+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 <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef MAX30100_FILTERS_H
+#define MAX30100_FILTERS_H
+
+// http://www.schwietering.com/jayduino/filtuino/
+// Low pass butterworth filter order=1 alpha1=0.1
+// Fs=100Hz, Fc=6Hz
+class  FilterBuLp1
+{
+    public:
+        FilterBuLp1()
+        {
+            v[0]=0.0;
+        }
+    private:
+        float v[2];
+    public:
+        float step(float x) //class II
+        {
+            v[0] = v[1];
+            v[1] = (2.452372752527856026e-1 * x)
+                 + (0.50952544949442879485 * v[0]);
+            return
+                 (v[0] + v[1]);
+        }
+};
+
+// http://sam-koblenski.blogspot.de/2015/11/everyday-dsp-for-programmers-dc-and.html
+class DCRemover
+{
+public:
+    DCRemover() : alpha(0), dcw(0)
+    {
+    }
+    DCRemover(float alpha_) : alpha(alpha_), dcw(0)
+    {
+    }
+
+    float step(float x)
+    {
+        float olddcw = dcw;
+        dcw = (float)x + alpha * dcw;
+
+        return dcw - olddcw;
+    }
+
+    float getDCW()
+    {
+        return dcw;
+    }
+
+private:
+    float alpha;
+    float dcw;
+};
+
+#endif
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