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Software/Python/grove_earclipheartrate/grove_earclipheartrate.py

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+# Code contributed by Alessandro Graps a.graps@joulehub.com
+# May 2020
+# Many thanks !!! 
+
+from datetime import datetime
+
+from datetime import timedelta
+import time
+import grovepi
+
+# Connect the Grove Ear Clip Sensor to digital port D3
+sensorPin = 3
+start_time = datetime.now()
+counter = 0
+temp = [0] * 21
+data_effect = True
+heart_rate = 0
+max_heartpulse_duty = 2000
+    
+def millis():
+   global start_time
+   dt = datetime.now() - start_time
+   ms = (dt.days * 24 * 60 * 60 + dt.seconds) * 1000 + dt.microseconds / 1000.0
+
+   return ms
+
+def arrayInit():  
+    global temp
+    global counter
+    counter = 0
+    temp = [0] * 21
+    temp[20] = millis()
+
+def sum():                               
+    global heart_rate, temp, data_effect
+    if data_effect:
+        heart_rate=1200000/(temp[20]-temp[0]);
+    
+def interrupt():
+    global counter
+    global temp
+    global data_effect
+    
+    temp[counter] = millis()
+    
+    if counter == 0:       
+        sub = temp[counter]-temp[20]
+    else:
+        sub = temp[counter]-temp[counter-1]
+
+    if sub > max_heartpulse_duty:
+        data_effect = False
+        counter = 0
+        arrayInit()
+    if counter == 20 and data_effect:
+        counter = 0
+        sum()
+    elif counter != 20 and data_effect:
+        counter += 1
+    else: 
+        counter = 0
+        data_effect = True
+
+def main():
+
+    global heart_rate
+    
+    print("Please place the sensor correctly")
+    time.sleep(4)
+    print("Starting measurement...")
+    arrayInit()
+    grovepi.set_pin_interrupt(sensorPin, grovepi.COUNT_CHANGES, grovepi.RISING, 1000)
+
+
+
+
+
+    while True:
+        value = grovepi.read_interrupt_state(sensorPin)
+        if value > 0:
+            interrupt()
+        time.sleep(0.73)
+        print("HR: {:2.0f}".format(heart_rate))
+     
+ 
+if __name__ == '__main__':
+    main()