Project Logs

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• Selection of microcontroller

  Rajendra Bhatt • 08/20/2014 at 02:52 • 0 comments

  The ADC block and microprocessor in the system design (described earlier) will be replaced by a single microcontroller with built-in ADC. This will simplify the design and reduce the cost. I am still debating with myself about choosing between the Arduino and PIC32 microcontroller.

• Filtering and amplifying raw PPG signal

  Rajendra Bhatt • 08/20/2014 at 02:48 • 0 comments

  Filtering and amplification of the raw PPG signal is required to match the signal characteristics with the ADC specifications. I am currently working on an operational amplifier based active band pass filter to get rid of noise and boost the PPG signal. I will update this section soon.

• Testing the HRM-2511E sensor

  Rajendra Bhatt • 08/20/2014 at 02:43 • 0 comments

  I quickly setup a simple biasing circuit on a breadboard to check the raw pulse signal from the HRM-2511E sensor. Here's my circuit setup for this test.

  I observed the waveform of the raw pulse signal output (Vout) from fingertip on my PC using my Analog Discovery tool from Digilent. The pulse signal waveform has amplitude of a few millivolts as shown below. This waveform was generated by wearing the sensor on my index finger.

• Sensor selection

  Rajendra Bhatt • 08/20/2014 at 02:16 • 0 comments

  I am going to use the HRM-2511E fingertip pulse sensor manufactured by Kyoto Electronic Co., China in the prototype of this project. I have worked with this sensor before and I have found it very easy to use, and provides stable output. The HRM-2511E sensor body is built with flexible Silicone rubber material that fits nicely on the top of a finger. Inside the sensor case, an IR LED and a photodetector are placed on two opposite sides and are facing each other. The necessary connections to the LED and photodiode pins are available through a 3.5mm stereo audio connector.

  HRM-2511E pulse sensor

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