Add: Filter for ECG

examples/Example2-ECG-Stream-Arduino-Plotter/Example2-ECG-Stream-Arduino-Plotter.ino

@@ -29,35 +29,82 @@
 
 #include <Wire.h>
 #include "max86150.h"
+#include <FIR.h>
 
 MAX86150 max86150Sensor;
 
-#define debug Serial      //Uncomment this line if you're using an Uno or ESP
+#define debug Serial // Uncomment this line if you're using an Uno or ESP
 //#define debug SerialUSB //Uncomment this line if you're using a SAMD21
 
 int16_t ecgsigned16;
 int16_t redunsigned16;
 
+FIR<long, 13> fir;
+
+/*
+
+FIR filter designed with
+ http://t-filter.appspot.com
+
+sampling frequency: 200 Hz
+
+fixed point precision: 16 bits
+
+* 0 Hz - 1 Hz
+  gain = 0
+  desired attenuation = -40 dB
+  actual attenuation = n/a
+
+* 2 Hz - 25 Hz
+  gain = 1
+  desired ripple = 10 dB
+  actual ripple = n/a
+
+* 26 Hz - 100 Hz
+  gain = 0
+  desired attenuation = -40 dB
+  actual attenuation = n/a
+
+*/
+long coef[13] = {
+	-364,
+	-103,
+	-42,
+	60,
+	173,
+	262,
+	295,
+	262,
+	173,
+	60,
+	-42,
+	-103,
+	-364};
+
 void setup()
 {
-    debug.begin(57600);
-    debug.println("MAX86150 Basic Readings Example");
+	debug.begin(57600);
+	debug.println("MAX86150 Basic Readings Example");
+
+	// Set the coefficients
+  fir.setFilterCoeffs(coef);
 
-    // Initialize sensor
-    if (max86150Sensor.begin(Wire, I2C_SPEED_FAST) == false)
-    {
-        debug.println("MAX86150 was not found. Please check wiring/power. ");
-        while (1);
-    }
+	// Initialize sensor
+	if (max86150Sensor.begin(Wire, I2C_SPEED_FAST) == false)
+	{
+		debug.println("MAX86150 was not found. Please check wiring/power. ");
+		while (1)
+			;
+	}
 
-    max86150Sensor.setup(); //Configure sensor
+	max86150Sensor.setup(); // Configure sensor
 }
 
 void loop()
 {
-    if(max86150Sensor.check()>0)
-    {
-        ecgsigned16 = (int16_t) (max86150Sensor.getFIFOECG()>>2);
-        debug.println(ecgsigned16);
-    }
+	if (max86150Sensor.check() > 0)
+	{
+		ecgsigned16 = (int16_t)(max86150Sensor.getECG() >> 2);
+		debug.println(fir.processReading(ecgsigned16));
+	}
 }

library.properties

@@ -1,9 +1,10 @@
 name=ProtoCentral MAX86150 PPG and ECG IC library
-version=1.0.0
+version=1.0.1
 author=ProtoCentral Electronics <support@protocentral.com>
 maintainer=ProtoCentral Electronics <protocentral.com>
 sentence=Library for the MAX86150 PPG and ECG sensor module breakout board
 paragraph=Arduino library for the MAX86150 PPG and ECG sensor module
 category=Sensors
 url=https://github.com/Protocentral/protocentral_max86150_ecg_ppg
 architectures=*
+depends=FIR filter

src/max86150.cpp

@@ -388,8 +388,9 @@ void MAX86150::setup(byte powerLevel, byte sampleAverage, byte ledMode, int samp
 
 		writeRegister8(_i2caddr,MAX86150_SYSCONTROL,0x04);//start FIFO
 
-		writeRegister8(_i2caddr,MAX86150_ECG_CONFIG1,0b00000011);
-		writeRegister8(_i2caddr,MAX86150_ECG_CONFIG3,0b00001101);
+		writeRegister8(_i2caddr,MAX86150_ECG_CONFIG1,0b00000011);///0b00000011); // SR: 200
+
+    writeRegister8(_i2caddr,MAX86150_ECG_CONFIG3,0b00001101); // IA Gain: 9.5 / PGA Gain: 8
 
 		setPulseAmplitudeRed(0xFF);
 		setPulseAmplitudeIR(0xFF);
@@ -640,4 +641,4 @@ void MAX86150::writeRegister8(uint8_t address, uint8_t reg, uint8_t value) {
   _i2cPort->write(reg);
   _i2cPort->write(value);
   _i2cPort->endTransmission();
-}
+}