Diff: max30101_algo.cpp

Revision:

1:efe9cad8942f

Child:

12:1300cb0f6274

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/max30101_algo.cpp	Tue Mar 13 14:52:59 2018 +0300
@@ -0,0 +1,579 @@
+/*******************************************************************************
+* Copyright (C) 2018 Maxim Integrated Products, Inc., All Rights Reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining a
+* copy of this software and associated documentation files (the "Software"),
+* to deal in the Software without restriction, including without limitation
+* the rights to use, copy, modify, merge, publish, distribute, sublicense,
+* and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*
+* Except as contained in this notice, the name of Maxim Integrated
+* Products, Inc. shall not be used except as stated in the Maxim Integrated
+* Products, Inc. Branding Policy.
+*
+* The mere transfer of this software does not imply any licenses
+* of trade secrets, proprietary technology, copyrights, patents,
+* trademarks, maskwork rights, or any other form of intellectual
+* property whatsoever. Maxim Integrated Products, Inc. retains all
+* ownership rights.
+*******************************************************************************
+*/
+
+#include "max30101_algo.h"
+
+//helper functions for the heart rate and SpO2 function
+uint16_t avg_dc_est(int32_t *p, uint16_t x);
+
+void lp_dfir_flt(int16_t din0, int16_t din1, int16_t din2, int16_t *dout0, int16_t *dout1, int16_t *dout2) ;
+int32_t mul16(int16_t x, int16_t y);
+
+//
+//  Heart Rate/SpO2 Monitor function takes sample input 'dinIR' and dinRed.
+//  Other inputs:
+//      ns -> Sample Counter, increments with each sample input.
+//      SampRate -> Input data real-time sample rate.
+//      dinLShft -> Number of left shifts for data to be 16 bit wide.
+//      compSpO2 -> If '1' compute SpO2 value,else compute HR only.
+
+//
+//  Outputs:
+//      ir_ac_comp  -> AC component of the IR signal.
+//      red_ac_comp -> AC component of the Red signal.
+//      ir_ac_mag   -> Peak to Peak magnitude of the IR signal.
+//      red_ac_mag  -> Peak to Peak magnitude of the Red signal.
+//      HRbpm       -> Heart Rate in beats per minute.
+//      SpO2        -> SpO2 value as %saturation.
+//      DRdy        -> '1' when new data is available.
+//
+
+void HRSpO2Func(uint32_t dinIR, uint32_t dinRed, uint32_t dinGreen, uint32_t ns, uint16_t SampRate, uint16_t compSpO2,
+	int16_t *ir_ac_comp, int16_t *red_ac_comp, int16_t *green_ac_comp, int16_t *ir_ac_mag, int16_t *red_ac_mag,
+	int16_t *green_ac_mag,    uint16_t *HRbpm2, uint16_t *SpO2B, uint16_t *DRdy)
+{
+	static int32_t ir_avg_reg = 0;
+	static int32_t red_avg_reg = 0;
+	static int32_t green_avg_reg = 0;
+
+	static int16_t ir_ac_sig_cur = 0;
+	static int16_t ir_ac_sig_pre;
+	static int16_t ir_ac_sig_min = 0;
+	static int16_t ir_ac_sig_max = 0;
+	static int16_t ir_avg_est;
+
+	static int16_t ir_pedge = 0, ir_nedge = 0;
+	static int16_t ir_pzxic, ir_pzxip;
+	static int16_t ir_nzxic;
+
+	static int16_t red_ac_sig_cur = 0;
+	static int16_t red_ac_sig_min = 0;
+	static int16_t red_ac_sig_max = 0;
+	static int16_t red_avg_est;
+
+	static int16_t green_avg_est;
+	static int16_t green_ac_sig_cur = 0;
+	//static int16_t green_ac_sig_cur=0;
+	static int16_t green_ac_sig_pre;
+	static int16_t green_ac_sig_max ;
+	static int16_t  green_ac_sig_min;
+	static int16_t green_mac_FIFO[5];
+	int16_t meanGreenMagFIFO;
+	int16_t minAmpForHeartBeat ;
+
+	uint32_t  IRData, RedData, greenData, rnum, rden, rdens;
+	uint16_t  zeros_in_HrQue = 0, posCount = 0;
+	static uint32_t prevPeakLoc = 0;
+	static int16_t IrFIFO[100];
+	static int16_t HrQue[10], lastKnownGoodHr[10];
+	static int16_t SPO2Que[5];
+	int16_t SPO2score[5];
+	static uint16_t HrQindex = 0, lengthOfposCountExceeding = 0;
+	static uint16_t initHrQueCounter = 0, fingerOff = 0;
+
+	static int16_t HrQueSmoothing[3];
+	static int16_t SPO2QueSmoothing[3];
+
+	int16_t  k, j;
+	uint32_t peakLoc ;
+	int16_t bufferIdx1,  bufferIdx2;
+	int16_t maxFIFO, IdxMaxFIFO ;
+	int16_t HRperiod2, HRComp2, deltaHR;
+	int16_t cSpO2, SpO2;
+
+	int16_t HrCount = 0, HrSum = 0, meanGreenMagFIFOcounter = 0;
+	int16_t SPO2D, meanHrQ;
+	int16_t dx[99], cumsumX[99];
+	static int16_t SPO2QueCounter = 0 ; //, lastDisplayedHrValue;
+
+	int16_t validSPO2Count = 0;
+	int16_t validSPO2Sum = 0;
+	int16_t SPO2scoreAverage =  0;
+	int16_t SPO2scoreSum = 0 ;
+	// int16_t deltaMeanLastKnownGoodHr = 0, meanLastKnownGoodHr = 0;
+	// int16_t counterMeanLastKnownGoodHr = 0;
+
+
+	/* clear some vars if fresh new start */
+	if ((ns == 0) || (fingerOff > 300)) {
+		ir_avg_reg = 0;
+		red_avg_reg = 0;
+		green_avg_reg = 0;
+
+		ir_ac_sig_cur = 0;
+		ir_ac_sig_pre = 0;
+		ir_ac_sig_min = 0;
+		ir_ac_sig_max = 0;
+
+		ir_avg_est = 0;
+		green_avg_est = 0;
+		red_avg_est = 0 ;
+
+		ir_pedge = 0;
+		ir_nedge = 0;
+		ir_pzxic = 0;
+		ir_pzxip = 0;
+		ir_nzxic = 0 ;
+		//ir_nzxip = 0;
+		red_ac_sig_cur = 0;
+		red_ac_sig_min = 0;
+		red_ac_sig_max = 0;
+
+		prevPeakLoc = 0 ;
+		bufferIdx1 = 0 ;
+		bufferIdx2 = 0;
+		HrQindex = 0;
+		initHrQueCounter = 0;
+		lengthOfposCountExceeding = 0 ;
+		fingerOff = 0;
+		HRComp2 = 0;
+
+		for (k = 0 ; k < 100 ; k++) {
+			IrFIFO[k] = 0;
+		}
+
+		for (k = 0 ; k < 10 ; k++) {
+			HrQue[k] = 0;
+			lastKnownGoodHr[k] = 0;
+		}
+
+		for (k = 0 ; k < 3 ; k++) {
+			HrQueSmoothing[k] = 70;
+			SPO2QueSmoothing[k] = 97;
+		}
+
+		for (k = 0 ; k < 5 ; k++) {
+			SPO2Que[k] = 97;
+			SPO2score[k] = 0;
+			green_mac_FIFO[k] = 0;
+		}
+
+		SPO2QueCounter = 0;
+		*SpO2B = 97;
+		*HRbpm2 = 0;
+		*DRdy = 0 ;
+	}
+
+
+	/* Save current state */
+	green_ac_sig_pre = green_ac_sig_cur;
+
+	/* Process next data sample */
+	minAmpForHeartBeat = 0;
+	IRData  = dinIR;
+	RedData = dinRed;
+	greenData = dinGreen ;
+
+	ir_avg_est  = avg_dc_est(&ir_avg_reg, IRData);
+	red_avg_est = avg_dc_est(&red_avg_reg, RedData);
+	green_avg_est = avg_dc_est(&green_avg_reg, greenData);
+
+	lp_dfir_flt((uint16_t)(IRData - ir_avg_est), (uint16_t)(RedData - red_avg_est),
+		(uint16_t)(greenData - green_avg_est),  &ir_ac_sig_cur, &red_ac_sig_cur, &green_ac_sig_cur);
+
+	*ir_ac_comp = ir_ac_sig_cur;
+	*red_ac_comp = red_ac_sig_cur;
+	*green_ac_comp = green_ac_sig_cur;
+
+	/* save to FIFO */
+	for (k = 1 ; k < 100 ; k++) {
+		IrFIFO[100 - k] = IrFIFO[99 - k];
+	}
+	IrFIFO[0] =  green_ac_sig_cur ; // invert
+	for (k = 0 ; k < 97 ; k++) {
+		dx[k] = IrFIFO[k + 2] - IrFIFO[k] ;
+	}
+	dx[97] = dx[96];
+	dx[98] = dx[96];
+
+	for (k = 0 ; k < 99 ; k++) {
+		if (dx[k] > 0) {
+			dx[k] = 1;
+		} else {
+			dx[k] = 0;
+		}
+	}
+
+	cumsumX[0] = 0;
+	for (k = 1; k < 99 ; k++) {
+		if (dx[k] > 0) {
+			cumsumX[k] =  cumsumX[k - 1] + dx[k] ;
+		} else {
+			cumsumX[k] =  0;
+		}
+	}
+
+	/* determine noise
+	 * ignore less than 3 consecutive non-zeros's
+	 * detect # of sign change
+	 */
+	posCount = 0;
+	for (k = 1; k < 99 ; k++) {
+		if (cumsumX[k] > 0) {
+			posCount ++ ;
+		} else if (cumsumX[k] == 0) {
+			if (posCount < 4  && k >= 4) {
+				for (j = k - 1; j > k - posCount - 1; j--) {
+					cumsumX[j] = 0 ;
+				}
+			}
+			posCount = 0;
+		}
+	}
+
+	/* ignore less than 3 consecutive zeros's */
+	posCount = 0;
+	for (k = 1; k < 99 ; k++) {
+		if (cumsumX[k] == 0) {
+			posCount ++ ;
+		} else if (cumsumX[k] > 0) {
+			if (posCount < 4  && k >= 4) {
+				for (j = k - 1; j > k - posCount - 1; j--) {
+					cumsumX[j] = 100 ;
+				}
+			}
+			posCount = 0;
+		}
+	}
+
+	/* detect # of sign change */
+	posCount = 0; /* sign change counter */
+	for (k = 0; k < 98 ; k++) {
+		if (cumsumX[k] == 0  && cumsumX[k + 1] > 0) {
+			posCount ++;
+		}
+	}
+	if (posCount >= 4) {
+		lengthOfposCountExceeding ++ ;
+	} else {
+		lengthOfposCountExceeding = 0 ;
+	}
+
+	/*  Detect IR channel positive zero crossing (rising edge) */
+	if ((green_ac_sig_pre < 0) && (green_ac_sig_cur >= 0) && fingerOff == 0) {
+		*ir_ac_mag = ir_ac_sig_max - ir_ac_sig_min;
+		*red_ac_mag = red_ac_sig_max - red_ac_sig_min;
+		*green_ac_mag = green_ac_sig_max - green_ac_sig_min;
+		if (*green_ac_mag > 0) {
+			for (k = 0; k < 4 ; k++) {
+				green_mac_FIFO[k] = green_mac_FIFO[k + 1];
+			}
+			green_mac_FIFO[4] = *green_ac_mag ;
+			if (green_mac_FIFO[4] > 1000) {
+				green_mac_FIFO[4] = 1000;
+			}
+		}
+		meanGreenMagFIFO = 0;
+		meanGreenMagFIFOcounter = 0;
+		for (k = 0; k < 5 ; k++) {
+			if (green_mac_FIFO[k] > 0) {
+				meanGreenMagFIFO = meanGreenMagFIFO + green_mac_FIFO[k] ;
+				meanGreenMagFIFOcounter++;
+			}
+		}
+		if (meanGreenMagFIFOcounter >= 2) {
+			meanGreenMagFIFO = meanGreenMagFIFO / meanGreenMagFIFOcounter ;
+			minAmpForHeartBeat = meanGreenMagFIFO / 4 ; //25% of mean of past heart beat
+		} else {
+			minAmpForHeartBeat = 75;
+		}
+		if (minAmpForHeartBeat < 75) {
+			minAmpForHeartBeat = 75;
+		}
+		if (minAmpForHeartBeat > 400) {
+			minAmpForHeartBeat = 400;
+		}
+
+		ir_pedge = 1;
+		ir_nedge = 0;
+		ir_ac_sig_max = 0;
+		ir_pzxip = ir_pzxic;
+		ir_pzxic = ns;
+		bufferIdx1 = ir_pzxic - ir_nzxic;
+		bufferIdx2 = ir_pzxic - ir_pzxip;
+
+		if ((*green_ac_mag) > minAmpForHeartBeat && (*green_ac_mag) < 20000 && bufferIdx1 >= 0
+			&& bufferIdx1 < 100 && bufferIdx2 >= 0 && bufferIdx2 < 100 && bufferIdx1 < bufferIdx2) { // was <5000
+			maxFIFO = -32766;
+
+			IdxMaxFIFO = 0;
+			for (j = bufferIdx1; j <= bufferIdx2; j++) { // find max peak
+				if (IrFIFO[j] > maxFIFO) {
+					maxFIFO = IrFIFO[j];
+					IdxMaxFIFO  = j;
+				}
+			}
+			peakLoc = ir_pzxic - IdxMaxFIFO + 1 ;
+
+			if (prevPeakLoc != 0) {
+				HRperiod2 = (uint16_t)(peakLoc -  prevPeakLoc);
+				if (HRperiod2 > 33 && HRperiod2 < 134) {
+					HRComp2 = (6000 / HRperiod2);
+					fingerOff = 0 ;
+				} else {
+					HRComp2 = 0 ;
+				}
+			} else {
+				HRComp2 = 0 ;
+			}
+
+			if (initHrQueCounter < 10  && HRComp2 > 0) {
+				HrQue[HrQindex] = HRComp2;
+				HrQindex++;
+				initHrQueCounter ++;
+				if (HrQindex == 10) {
+					HrQindex  = 0;
+				}
+			}
+
+			if (initHrQueCounter > 7 && lengthOfposCountExceeding <= 3) {
+				if (HRComp2 > 0) {
+
+					HrCount = 0;
+					HrSum = 0;
+					zeros_in_HrQue = 0;
+					for (k = 1 ; k < initHrQueCounter ; k++) {
+						if (HrQue[k] > 0) {
+							HrSum += HrQue[k];
+							HrCount ++;
+						} else {
+							zeros_in_HrQue ++;
+						}
+					}
+					meanHrQ = HrSum / HrCount ;
+					deltaHR = lastKnownGoodHr[0] / 10;
+
+					if (HRComp2 >  lastKnownGoodHr[0] - deltaHR &&  HRComp2  < lastKnownGoodHr[0] + deltaHR) {
+						for (k = 1 ; k < 10 ; k++) {
+							HrQue[10 - k] = HrQue[9 - k];
+						}
+						HrQue[0] = HRComp2;
+					} /* HR smoothing using FIFO queue */
+
+					if (zeros_in_HrQue <= 2) {
+						for (k = 1 ; k < 3 ; k++) {
+							HrQueSmoothing[3 - k] = HrQueSmoothing[2 - k];
+						}
+						HrQueSmoothing[0] = meanHrQ ;
+						HRComp2 = ((HrQueSmoothing[0] << 2) + (HrQueSmoothing[1] << 1) + (HrQueSmoothing[2] << 1)) >> 3;
+						*HRbpm2 = HRComp2 ;
+
+						for (k = 1 ; k < 10 ; k++) {
+							lastKnownGoodHr[10 - k] = lastKnownGoodHr[9 - k];
+						}
+						lastKnownGoodHr[0] = HRComp2;
+					}
+				}
+
+			} else if (initHrQueCounter < 7) { /* before que is filled up, display whatever it got. */
+				*HRbpm2 =  HRComp2;
+
+			} else {
+				//  *HRbpm2 =  0 ;
+				HrCount = 0;
+				HrSum = 0;
+				for (k = 0 ; k < 10 ; k++) {
+					if (lastKnownGoodHr[k] > 0) {
+						HrSum = HrSum + lastKnownGoodHr[k];
+						HrCount++;
+					}
+				}
+				if (HrCount > 0) {
+					*HRbpm2 = HrSum / HrCount;
+				} else {
+					*HRbpm2 = 0;
+				}
+			}
+			prevPeakLoc = peakLoc ; /* save peakLoc into Static var */
+
+			if (compSpO2) {
+				rnum = (ir_avg_reg >> 20) * (*red_ac_mag);
+				rden = (red_avg_reg >> 20) * (*ir_ac_mag);
+				rdens = (rden >> 15);
+				if (rdens > 0) {
+					cSpO2 = 110 - (((25 * rnum) / (rdens)) >> 15);
+				}
+
+				if (cSpO2 >= 100) {
+					SpO2 = 100;
+				} else if (cSpO2 <= 70) {
+					SpO2 = 70;
+				} else {
+					SpO2 = cSpO2;
+				}
+
+				SPO2Que[SPO2QueCounter ] = SpO2;
+
+				for (k = 0 ; k < 5 ; k++) {
+					SPO2score[k] = 0;
+					for (j = 0 ; j < 5 ; j++)
+						if (abs(SPO2Que[k] - SPO2Que[j]) > 5) {
+							SPO2score[k] ++;
+						}
+				}
+
+				SPO2scoreSum =  0;
+				for (k = 0 ; k < 5 ; k++) {
+					SPO2scoreSum += SPO2score[k] ;
+				}
+				SPO2scoreAverage = SPO2scoreSum / 5;
+				for (k = 1 ; k < 5 ; k++) {
+					SPO2score[k] = SPO2score[k] - SPO2scoreAverage;
+				}
+
+				validSPO2Count = 0;
+				validSPO2Sum = 0;
+				for (k = 1 ; k < 5 ; k++) {
+					if (SPO2score[k] <= 0) { // add for HR to report
+						validSPO2Sum += SPO2Que[k];
+						validSPO2Count ++;
+					}
+				}
+				if (validSPO2Count > 0) {
+					SPO2D = (validSPO2Sum / validSPO2Count) - 1;
+				}
+				if (SPO2D > 100) {
+					SPO2D = 100;
+				}
+
+				SPO2QueCounter ++;
+				if (SPO2QueCounter == 5) {
+					SPO2QueCounter = 0;
+				}
+
+				for (k = 1 ; k < 3 ; k++) {
+					SPO2QueSmoothing[3 - k] = SPO2QueSmoothing[2 - k];
+				}
+				SPO2QueSmoothing[0] = SPO2D;
+				*SpO2B = ((SPO2QueSmoothing[0] << 2) + (SPO2QueSmoothing[1] << 1) + (SPO2QueSmoothing[2] << 1)) >> 3;
+
+				if (*SpO2B > 100) {
+					*SpO2B = 100 ;
+				}
+
+			} else {
+				SpO2 = 0;
+				*SpO2B = 0;
+			}
+			*DRdy = 1;
+
+		}
+	}
+
+	/* Detect IR channel negative zero crossing (falling edge) */
+	if ((green_ac_sig_pre > 0) && (green_ac_sig_cur <= 0)) {
+		ir_pedge = 0;
+		ir_nedge = 1;
+		ir_ac_sig_min = 0;
+		ir_nzxic = ns;
+	}
+
+	/* Find Maximum IR & Red values in positive cycle */
+	if (ir_pedge && (green_ac_sig_cur > green_ac_sig_pre)) {
+		ir_ac_sig_max  = ir_ac_sig_cur;
+		red_ac_sig_max = red_ac_sig_cur;
+		green_ac_sig_max = green_ac_sig_cur;
+	}
+
+	/* Find minimum IR & Red values in negative cycle */
+	if (ir_nedge && (green_ac_sig_cur < green_ac_sig_pre)) {
+		ir_ac_sig_min  = ir_ac_sig_cur;
+		red_ac_sig_min = red_ac_sig_cur;
+		green_ac_sig_min = green_ac_sig_cur;
+	}
+
+	if (IRData < 50000) {
+		// finger-off
+		fingerOff++;
+		*DRdy = 0;
+	} else {
+		fingerOff = 0 ;
+	}
+
+	if (*SpO2B ==  0  ||   *HRbpm2 == 0) {
+		*DRdy = 0;
+	}
+}
+
+/*
+ * Average DC Estimator
+ */
+uint16_t avg_dc_est(int32_t *p, uint16_t x)
+{
+	*p += ((((int32_t) x << 15) - *p) >> 4);
+	return (*p >> 15);
+}
+
+/*
+ * Symmetric Dual Low Pass FIR Filter
+ */
+void lp_dfir_flt(int16_t din0, int16_t din1, int16_t din2, int16_t *dout0, int16_t *dout1, int16_t *dout2)
+{
+	static const uint16_t FIRCoeffs[12] = {688, 1283, 2316, 3709, 5439, 7431,
+			9561, 11666, 13563, 15074, 16047, 16384
+		};
+
+	static int16_t cbuf0[32], cbuf1[32], cbuf2[32];
+	static int16_t offset = 0;
+	int32_t y0, y1, y2;
+	int16_t i;
+
+	cbuf0[offset] = din0;
+	cbuf1[offset] = din1;
+	cbuf2[offset] = din2;
+
+	y0 = mul16(FIRCoeffs[11], cbuf0[(offset - 11) & 0x1F]);
+	y1 = mul16(FIRCoeffs[11], cbuf1[(offset - 11) & 0x1F]);
+	y2 = mul16(FIRCoeffs[11], cbuf2[(offset - 11) & 0x1F]);
+
+
+	for (i = 0; i < 11; i++) {
+		y0 += mul16(FIRCoeffs[i], cbuf0[(offset - i) & 0x1F] + cbuf0[(offset - 22 + i) & 0x1F]);
+		y1 += mul16(FIRCoeffs[i], cbuf1[(offset - i) & 0x1F] + cbuf1[(offset - 22 + i) & 0x1F]);
+		y2 += mul16(FIRCoeffs[i], cbuf2[(offset - i) & 0x1F] + cbuf2[(offset - 22 + i) & 0x1F]);
+	}
+	offset = (offset + 1) & 0x1F;
+
+	*dout0 = (y0 >> 15);
+	*dout1 = (y1 >> 15);
+	*dout2 = (y2 >> 15);
+}
+
+/*
+ * Integer multiplier
+ */
+int32_t mul16(int16_t x, int16_t y)
+{
+	return (int32_t)(x * y);
+}
+