ad3bf49c7b
- Combine the reading of all `HRS3300` registers into one I2C read so data is not partial
- Downsizes both HRS and ALS to 16bit as the sensor does not generate larger than
16bit values in its current configuration
- Increasing the resolution by 1 bit doubles the sensor acquisition time,
since we are already at 10Hz we are never going to use a higher resolution
- The PPG algorithm buffers for ALS/HRS are already 16bit anyway
- Remove functions for setting gain / drive that are unused throughout the codebase
- Calculate constants with constexpr
81 lines
3.1 KiB
C++
81 lines
3.1 KiB
C++
#pragma once
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#include <array>
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#include <cstddef>
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#include <cstdint>
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// Note: Change internal define 'sqrt_internal sqrt' to
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// 'sqrt_internal sqrtf' to save ~3KB of flash.
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#define sqrt_internal sqrtf
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#define FFT_SPEED_OVER_PRECISION
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#include "libs/arduinoFFT/src/arduinoFFT.h"
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namespace Pinetime {
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namespace Controllers {
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class Ppg {
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public:
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Ppg();
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int8_t Preprocess(uint16_t hrs, uint16_t als);
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int HeartRate();
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void Reset(bool resetDaqBuffer);
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static constexpr int deltaTms = 100;
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// Daq dataLength: Must be power of 2
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static constexpr uint16_t dataLength = 64;
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static constexpr uint16_t spectrumLength = dataLength >> 1;
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private:
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// The sampling frequency (Hz) based on sampling time in milliseconds (DeltaTms)
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static constexpr float sampleFreq = 1000.0f / static_cast<float>(deltaTms);
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// The frequency resolution (Hz)
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static constexpr float freqResolution = sampleFreq / dataLength;
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// Number of samples before each analysis
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// 0.5 second update rate at 10Hz
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static constexpr uint16_t overlapWindow = 5;
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// Maximum number of spectrum running averages
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// Note: actual number of spectra averaged = spectralAvgMax + 1
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static constexpr uint16_t spectralAvgMax = 2;
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// Multiple Peaks above this threshold (% of max) are rejected
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static constexpr float peakDetectionThreshold = 0.6f;
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// Maximum peak width (bins) at threshold for valid peak.
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static constexpr float maxPeakWidth = 2.5f;
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// Metric for spectrum noise level.
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static constexpr float signalToNoiseThreshold = 3.0f;
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// Heart rate Region Of Interest begin (bins)
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static constexpr uint16_t hrROIbegin = static_cast<uint16_t>((30.0f / 60.0f) / freqResolution + 0.5f);
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// Heart rate Region Of Interest end (bins)
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static constexpr uint16_t hrROIend = static_cast<uint16_t>((240.0f / 60.0f) / freqResolution + 0.5f);
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// Minimum HR (Hz)
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static constexpr float minHR = 40.0f / 60.0f;
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// Maximum HR (Hz)
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static constexpr float maxHR = 230.0f / 60.0f;
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// Threshold for high DC level after filtering
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static constexpr float dcThreshold = 0.5f;
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// ALS detection factor
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static constexpr float alsFactor = 2.0f;
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// Raw ADC data
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std::array<uint16_t, dataLength> dataHRS;
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// Stores Real numbers from FFT
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std::array<float, dataLength> vReal;
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// Stores Imaginary numbers from FFT
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std::array<float, dataLength> vImag;
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// Stores power spectrum calculated from FFT real and imag values
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std::array<float, (spectrumLength)> spectrum;
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// Stores each new HR value (Hz). Non zero values are averaged for HR output
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std::array<float, 20> dataAverage;
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uint16_t avgIndex = 0;
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uint16_t spectralAvgCount = 0;
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float lastPeakLocation = 0.0f;
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uint16_t alsThreshold = UINT16_MAX;
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uint16_t alsValue = 0;
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uint16_t dataIndex = 0;
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float peakLocation;
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bool resetSpectralAvg = true;
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int ProcessHeartRate(bool init);
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float HeartRateAverage(float hr);
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void SpectrumAverage(const float* data, float* spectrum, int length, bool reset);
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};
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}
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}
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