Question

我找到了一个代码，但是我不太了解BPM的公式=（1.0 / PulseInterval）* 60.0 * 1000; 60.0应该是1分钟（每分钟的心跳数），但为什么是1.0 / PulseInterval）和* 1000？

    int UpperThreshold = 518;
int LowerThreshold = 490;
int reading = 0;
float BPM = 0.0;
bool IgnoreReading = false;
bool FirstPulseDetected = false;
unsigned long FirstPulseTime = 0;
unsigned long SecondPulseTime = 0;
unsigned long PulseInterval = 0;
const unsigned long delayTime = 10;
const unsigned long delayTime2 = 1000;
const unsigned long baudRate = 9600;
unsigned long previousMillis = 0;
unsigned long previousMillis2 = 0;
int Signal;
void bpm() {
    reading = Signal;
    // Heart beat leading edge detected.
    if (reading > UpperThreshold && IgnoreReading == false) {
        if (FirstPulseDetected == false) {
            FirstPulseTime = millis();
            FirstPulseDetected = true;
        } else {
            SecondPulseTime = millis();
            PulseInterval = SecondPulseTime - FirstPulseTime;
            FirstPulseTime = SecondPulseTime;
        }
        IgnoreReading = true;
if (reading < LowerThreshold && IgnoreReading == true) {
        IgnoreReading = false;
        noTone(pinSPEAKER);
        digitalWrite(blinkPin, LOW);
    }
    // Calculate Beats Per Minute.
    BPM = (1.0 / PulseInterval) * 60.0 * 1000;
}

Answer 1

脉冲间隔以毫秒为单位。除以1000得到秒。您不希望每秒跳动，而是每分钟跳动。一分钟有60秒。除以60x1000，从毫秒变为分钟。

脉冲间隔的另一个名称是脉冲周期。

周期的倒数就是频率。

好像millis（）将时钟值转换为毫秒。

应解释BPM公式

1 个答案: