From c22e30a4a6ef014c7a5086ad47eaab7740a75ff2 Mon Sep 17 00:00:00 2001
From: Ceimour <113631258+Ceimour@users.noreply.github.com>
Date: Sun, 30 Apr 2023 08:50:18 -0500
Subject: Refactored Ppg for frequency based algorithm. (#1486)

New implementation of the heart rate sensor data processing using a frequency based PPG algorithm.
The HRS3300 settings are fine-tuned for better signal to noise at 10Hz.
The measurement delay is now set to 100ms.
Enable and use the ambient light sensor.
FFT implementation based on ArduinoFFT (https://github.com/kosme/arduinoFFT, GPLv3.0).
---
 .../arduinoFFT-develop/Examples/FFT_02/FFT_02.ino  | 125 +++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 src/libs/arduinoFFT-develop/Examples/FFT_02/FFT_02.ino

(limited to 'src/libs/arduinoFFT-develop/Examples/FFT_02')

diff --git a/src/libs/arduinoFFT-develop/Examples/FFT_02/FFT_02.ino b/src/libs/arduinoFFT-develop/Examples/FFT_02/FFT_02.ino
new file mode 100644
index 00000000..7164dab1
--- /dev/null
+++ b/src/libs/arduinoFFT-develop/Examples/FFT_02/FFT_02.ino
@@ -0,0 +1,125 @@
+/*
+
+	Example of use of the FFT libray to compute FFT for several signals over a range of frequencies.
+        The exponent is calculated once before the excecution since it is a constant.
+        This saves resources during the excecution of the sketch and reduces the compiled size.
+        The sketch shows the time that the computing is taking.
+        
+  Copyright (C) 2014 Enrique Condes
+  Copyright (C) 2020 Bim Overbohm (header-only, template, speed improvements)
+
+	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/>.
+
+*/
+
+#include "arduinoFFT.h"
+
+/*
+These values can be changed in order to evaluate the functions
+*/
+const uint16_t samples = 64;
+const double sampling = 40;
+const uint8_t amplitude = 4;
+const double startFrequency = 2;
+const double stopFrequency = 16.4;
+const double step_size = 0.1;
+
+/*
+These are the input and output vectors
+Input vectors receive computed results from FFT
+*/
+double vReal[samples];
+double vImag[samples];
+
+/* Create FFT object */
+ArduinoFFT<double> FFT = ArduinoFFT<double>(vReal, vImag, samples, sampling);
+
+unsigned long startTime;
+
+#define SCL_INDEX 0x00
+#define SCL_TIME 0x01
+#define SCL_FREQUENCY 0x02
+#define SCL_PLOT 0x03
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println("Ready");
+}
+
+void loop()
+{
+  Serial.println("Frequency\tDetected\ttakes (ms)");
+  Serial.println("=======================================\n");
+  for(double frequency = startFrequency; frequency<=stopFrequency; frequency+=step_size)
+  {
+    /* Build raw data */
+    double cycles = (((samples-1) * frequency) / sampling);
+    for (uint16_t i = 0; i < samples; i++)
+    {
+      vReal[i] = int8_t((amplitude * (sin((i * (TWO_PI * cycles)) / samples))) / 2.0);
+      vImag[i] = 0; //Reset the imaginary values vector for each new frequency
+    }
+    /*Serial.println("Data:");
+    PrintVector(vReal, samples, SCL_TIME);*/
+    startTime=millis();
+    FFT.windowing(FFTWindow::Hamming, FFTDirection::Forward);	/* Weigh data */
+    /*Serial.println("Weighed data:");
+    PrintVector(vReal, samples, SCL_TIME);*/
+    FFT.compute(FFTDirection::Forward); /* Compute FFT */
+    /*Serial.println("Computed Real values:");
+    PrintVector(vReal, samples, SCL_INDEX);
+    Serial.println("Computed Imaginary values:");
+    PrintVector(vImag, samples, SCL_INDEX);*/
+    FFT.complexToMagnitude(); /* Compute magnitudes */
+    /*Serial.println("Computed magnitudes:");
+    PrintVector(vReal, (samples >> 1), SCL_FREQUENCY);*/
+    double x = FFT.majorPeak();
+    Serial.print(frequency);
+    Serial.print(": \t\t");
+    Serial.print(x, 4);
+    Serial.print("\t\t");
+    Serial.print(millis()-startTime);
+    Serial.println(" ms");
+    // delay(2000); /* Repeat after delay */
+  }
+  while(1); /* Run Once */
+}
+
+void PrintVector(double *vData, uint16_t bufferSize, uint8_t scaleType)
+{
+  for (uint16_t i = 0; i < bufferSize; i++)
+  {
+    double abscissa;
+    /* Print abscissa value */
+    switch (scaleType)
+    {
+      case SCL_INDEX:
+        abscissa = (i * 1.0);
+	break;
+      case SCL_TIME:
+        abscissa = ((i * 1.0) / sampling);
+	break;
+      case SCL_FREQUENCY:
+        abscissa = ((i * 1.0 * sampling) / samples);
+	break;
+    }
+    Serial.print(abscissa, 6);
+    if(scaleType==SCL_FREQUENCY)
+      Serial.print("Hz");
+    Serial.print(" ");
+    Serial.println(vData[i], 4);
+  }
+  Serial.println();
+}
-- 
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