Diff: MAX30100_PulseOximeter.cpp

Revision:

0:010b908e2187

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MAX30100_PulseOximeter.cpp	Fri Nov 25 00:52:54 2016 +0000
@@ -0,0 +1,154 @@
+/*
+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/>.
+*/
+
+#include <mbed.h>
+#include "MAX30100_PulseOximeter.h"
+
+
+PulseOximeter::PulseOximeter() :
+    state(PULSEOXIMETER_STATE_INIT),
+//    tsFirstBeatDetected(0),
+//    tsLastBeatDetected(0),
+//    tsLastSample(0),
+//    tsLastBiasCheck(0),
+//    tsLastCurrentAdjustment(0),
+    redLedPower((uint8_t)RED_LED_CURRENT_START),
+    onBeatDetected(NULL)
+{
+}
+
+bool PulseOximeter::begin(PulseOximeterDebuggingMode debuggingMode_)
+{
+    debuggingMode = debuggingMode_;
+
+    if(!hrm.begin())
+        return false;
+    if(!hrm.setMode(MAX30100_MODE_SPO2_HR))
+        return false;
+    if(!hrm.setLedsCurrent(IR_LED_CURRENT, RED_LED_CURRENT_START))
+        return false;
+
+    irDCRemover = DCRemover(DC_REMOVER_ALPHA);
+    redDCRemover = DCRemover(DC_REMOVER_ALPHA);
+
+    state = PULSEOXIMETER_STATE_IDLE;
+    return true;
+}
+
+
+void PulseOximeter::update()
+{
+    checkSample();
+    checkCurrentBias();   
+}
+
+float PulseOximeter::getHeartRate()
+{
+    return beatDetector.getRate();
+}
+
+uint8_t PulseOximeter::getSpO2()
+{
+    return spO2calculator.getSpO2();
+}
+
+uint8_t PulseOximeter::getRedLedCurrentBias()
+{
+    return redLedPower;
+}
+
+void PulseOximeter::setOnBeatDetectedCallback(void (*cb)())
+{
+    onBeatDetected = cb;
+    t_Sample.start();
+    t_CurrentBias.start();
+}
+
+void PulseOximeter::checkSample()
+{
+    if (t_Sample.read_ms() > 1.0 / SAMPLING_FREQUENCY * 1000.0) {
+        t_Sample.reset();
+        if(hrm.update()){
+            
+            float irACValue = irDCRemover.step(hrm.rawIRValue);
+            float redACValue = redDCRemover.step(hrm.rawRedValue);
+    
+            // The signal fed to the beat detector is mirrored since the cleanest monotonic spike is below zero
+            float filteredPulseValue = lpf.step(-irACValue);
+            bool beatDetected = beatDetector.addSample(filteredPulseValue);
+    
+            if (beatDetector.getRate() > 0) {
+                state = PULSEOXIMETER_STATE_DETECTING;
+                spO2calculator.update(irACValue, redACValue, beatDetected);
+            } else if (state == PULSEOXIMETER_STATE_DETECTING) {
+                state = PULSEOXIMETER_STATE_IDLE;
+                spO2calculator.reset();
+            }
+            /*
+            switch (debuggingMode) {
+                case PULSEOXIMETER_DEBUGGINGMODE_RAW_VALUES:
+                    Serial.print("R:");
+                    Serial.print(hrm.rawIRValue);
+                    Serial.print(",");
+                    Serial.println(hrm.rawRedValue);
+                    break;
+    
+                case PULSEOXIMETER_DEBUGGINGMODE_AC_VALUES:
+                    Serial.print("R:");
+                    Serial.print(irACValue);
+                    Serial.print(",");
+                    Serial.println(redACValue);
+                    break;
+    
+                case PULSEOXIMETER_DEBUGGINGMODE_PULSEDETECT:
+                    Serial.print("R:");
+                    Serial.print(filteredPulseValue);
+                    Serial.print(",");
+                    Serial.println(beatDetector->getCurrentThreshold());
+                    break;
+    
+                default:
+                    break;
+            }
+            */
+            if (beatDetected && onBeatDetected) {
+                onBeatDetected();
+            }
+        }
+    }
+}
+
+void PulseOximeter::checkCurrentBias()
+{
+    // Follower that adjusts the red led current in order to have comparable DC baselines between
+    // red and IR leds. The numbers are really magic: the less possible to avoid oscillations
+    if (t_CurrentBias.read_ms() > CURRENT_ADJUSTMENT_PERIOD_MS) {
+        bool changed = false;
+        if (irDCRemover.getDCW() - redDCRemover.getDCW() > 70000 && redLedPower < MAX30100_LED_CURR_50MA) {
+            ++redLedPower;
+            changed = true;
+        } else if (redDCRemover.getDCW() - irDCRemover.getDCW() > 70000 && redLedPower > 0) {
+            --redLedPower;
+            changed = true;
+        }
+
+        if (changed) {
+            hrm.setLedsCurrent(IR_LED_CURRENT, (LEDCurrent)redLedPower);
+            //tsLastCurrentAdjustment = millis();
+        }
+
+        t_CurrentBias.reset();
+    }
+}