Project17.Pulse Rate Monitor
===============================

Description
------------
This module makes use of a ultra-clear infrared LED and a phototransistor to 
detect the pulse in your finger. The red LED will flash in time with your pulse.

Shine the bright LED onto one side of your finger while the phototransistor on 
the other side of your finger picks up the amount of transmitted light. The 
resistance of the phototransistor will vary slightly as the blood pulses through 
your finger.

Specification
--------------

Connect
--------
.. image:: /img/connect/17_bb.png

Code
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.. code-block:: c

    int ledPin = 13;
    int sensorPin = 0;
    double alpha = 0.75;
    int period = 20;
    double change = 0.0;
    void setup()
    {
    pinMode(ledPin, OUTPUT);
    Serial.begin(115200);
    }
    void loop()
    {
    static double oldValue = 0;
    static double oldChange = 0;
    int rawValue = analogRead(sensorPin);
    double value = alpha * oldValue + (1 - alpha) * rawValue;
    Serial.print(rawValue);
    Serial.print(",");
    Serial.println(value);
    oldValue = value;
    delay(period);
    }



Phenomenon
-----------


.. image:: /img/phenomenon/17.jpg