想问一下，
1、程序里变量IBI、Peak、Trough、thresh、amp的初始值为什么是600、512、100？
2、void rountine(void)函数N > (IBI/5)*3，N > 250是为什么？
（如果你们有相关讲解视频希望能分享一下，好人一生平安）
volatile unsigned int BPM; // used to hold the pulse rate
volatile unsigned long Signal; // holds the incoming raw data
volatile unsigned int IBI = 600; // holds the time between beats, must be seeded!
volatile bit Pulse = false; // true when pulse wave is high, false when it's low
volatile bit QS = false; // becomes true when Arduoino finds a beat.
volatile int rate[10]; // array to hold last ten IBI values
volatile unsigned long sampleCounter = 0; // used to determine pulse timing
volatile unsigned long lastBeatTime = 0; // used to find IBI
volatile int Peak =512; // used to find peak in pulse wave, seeded
volatile int Trough = 512; // used to find trough in pulse wave, seeded
volatile int thresh = 512; // used to find instant moment of heart beat, seeded
volatile int amp = 100; // used to hold amplitude of pulse waveform, seeded
volatile bit firstBeat = true; // used to seed rate array so we startup with reasonable BPM
volatile bit secondBeat = false; // used to seed rate array so we startup with reasonable BPM
void rountine(void)//获取心率
{
int N;
unsigned char i;
// keep a running total of the last 10 IBI values
unsigned int runningTotal = 0; // clear the runningTotal variable
EA=0; // disable interrupts while we do this
TL0 = 0xCD; //2ms
TH0 = 0xF8;
Signal = Read_ADC0832(0)<<2; // read the Pulse Sensor
sampleCounter += 2; // keep track of the time in mS with this variable
N = sampleCounter - lastBeatTime; // monitor the time since the last beat to avoid noise
// find the peak and trough of the pulse wave
if(Signal < thresh && N > (IBI/5)*3)
{ // avoid dichrotic noise by waiting 3/5 of last IBI
if (Signal < Trough)
{ // T is the trough
Trough = Signal; // keep track of lowest point in pulse wave
}
}
if(Signal > thresh && Signal > Peak)
{ // thresh condition helps avoid noise
Peak = Signal; // P is the peak
} // keep track of highest point in pulse wave
// NOW IT'S TIME TO LOOK FOR THE HEART BEAT
// signal surges up in value every time there is a pulse
if (N > 250)
{ // avoid high frequency noise
if ( (Signal > thresh) && (Pulse == false) && (N > (IBI/5)*3) )
{
Pulse = true; // set the Pulse flag when we think there is a pulse
// turn on pin 13 LED
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 secondBeat flag
for(i=0; i<=9; i++)
{ // seed the running total to get a realisitic BPM at startup
rate[i] = IBI;
}
}
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
EA=1; // enable interrupts again
return; // IBI value is unreliable so discard it
}
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!
if(BPM<150&&BPM>60)
{
heartrate=BPM;
}
else
{
heartrate=0;
}
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
// turn off pin 13 LED
Pulse = false; // reset the Pulse flag so we can do it again
amp = Peak - Trough; // get amplitude of the pulse wave
thresh = amp/2 + Trough; // set thresh at 50% of the amplitude
Peak = thresh; // reset these for next time
Trough = thresh;
}
if (N > 2500)
{ // if 2.5 seconds go by without a beat
thresh = 512; // set thresh default
Peak = 512; // set P default
Trough = 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
}
heartrate = adc_value*1.0113;
//EA=1; // enable interrupts when youre done!
}