有人做过pruse sensor 开源心率传感器的开发吗?

laokin · 发表于 2018-4-17 13:25:30

这段代码测量  用了什么原理去检测心率的？
void TIM3_IRQHandler(void)
{
uint16_t runningTotal=0;
uint8_t i;
uint16_t Num;

if(TIM_GetITStatus(TIM3,TIM_IT_Update)!=RESET)
{

Signal = ADC_GetConversionValue(ADC1)/4;    // read the Pulse Senso
sampleCounter += 2;                         // keep track of the time in mS with this variable
Num = sampleCounter - lastBeatTime;       // monitor the time since the last beat to avoid noise

//  find the peak and trough of the pulse wave
if(Signal < thresh && Num > (IBI/5)*3) // avoid dichrotic noise by waiting 3/5 of last IBI
{
if (Signal < T)                         // T is the trough
{
T = Signal;                         // keep track of lowest point in pulse wave
}
}

if(Signal > thresh && Signal > P)            // thresh condition helps avoid noise    thresh ìõ¼tóDÖúóú±üÃaÔëòô
{
P = Signal;                               // P is the peak P êÇò»¸ö¼a·å
}                                           // keep track of highest point in pulse wave  ¸ú×ùÂö2«2¨μÄ×î¸ßμã

//  NOW IT'S TIME TO LOOK FOR THE HEART BEAT
// signal surges up in value every time there is a pulse
if (Num > 250)                               // avoid high frequency noise
{
if ( (Signal > thresh) && (Pulse == false) && (Num > (IBI/5)*3) )
{
Pulse = true;                            // set the Pulse flag when we think there is a pulse
IBI = sampleCounter - lastBeatTime;       // measure time between beats in mS
lastBeatTime = sampleCounter;             // keep track of time for next pulse

if(secondBeat)                      // if this is the second beat, if secondBeat == TRUE
{
secondBeat = false;                // clear second Beat flag
for(i=0; i<=9; i++)                // seed the running total to get a realisitic BPM at startup
{
rate[i] = IBI;                   //rate[0]-rate[9]
}
}

if(firstBeat)                      // if it's the first time we found a beat, if firstBeat == TRUE
{
firstBeat = false;                // clear firstBeat flag
secondBeat = true;                // set the second beat flag
return;                            // IBI value is unreliable so discard it  IBI
}

// keep a running total of the last 10 IBI values
// runningTotal = 0;                   // clear the runningTotal variable
for(i=0; i<=8; i++)                   // shift data in the rate array
{
rate[i] = rate[i+1];                // and drop the oldest IBI value
runningTotal += rate[i];             // add up the 9 oldest IBI values
}

rate[9] = IBI;                         // add the latest IBI to the rate array
runningTotal += rate[9];             // add the latest IBI to runningTotal
runningTotal /= 10;                   // average the last 10 IBI values
BPM = 60000/runningTotal;             // how many beats can fit into a minute? that's BPM
QS = true;                            // set Quantified Self flag
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
}
}

if (Signal < thresh && Pulse == true) // when the values are going down, the beat is over
{
Pulse = false;                      // reset the Pulse flag so we can do it again
amp = P - T;                         // get amplitude of the pulse wave
thresh = amp/2 + T;                   // set thresh at 50% of the amplitude
P = thresh;                         // reset these for next time
T = thresh;
}

if (Num > 2500)                      // if 2.5 seconds go by without a beat
{
thresh = 512;                         // set thresh default
P = 512;                            // set P default
T = 512;                            // set T default
lastBeatTime = sampleCounter;       // bring the lastBeatTime up to date
firstBeat = true;                   // set these to avoid noise
secondBeat = false;                   // when we get the heartbeat back
}

}
TIM_ClearITPendingBit(TIM3,TIM_IT_Update);
}