ECG:MSP430FG439

Just a thought,  If the  fingers are too dry, the signal will not be detected reliably. Are you using the exact board as in the App note? Did you build your own? Some more information will be needed.

Gustavo

Sir ,

Yes I have made the exact board as given in the application note.  The person's who were unable to check their heart rate retry after applying some moisture to the hand.  But they are unable to get the result.

When they put their the four arrow symbol which signifies the detection of the pulse blinks only for once or twice and some result is displayed.  It is not the result as result is calculated on the basis of the three consecutive pulse interval.  Further when the person do not leave his or her hand the no sign of  pulse detection is seen on LCD.  

Please make a note that this happens to only few person.  On an average out of 10 person 8 can check there heart rate easily only 2 are unable to check......

I have absolutely no idea how this monitor works (haven't looked at the files at all), but I can guess that it might fail if the persons in question have a low blood pressure. Base don the hint with the moisture, I guess, the measuring takes place by comparing the change in contact resistance while a heatbeat happens. If the blood pressure is too low (or they have thick skin on their fingers), this pulse will not cause a high-enough resistance change to be detected.

Just plain guessing.

thank you for your efforts............ But your guessing goes totally against the working principle of the circuit........ Electrochemical impulse are used for the heart beat calculation.  

[deleted because obsolete]

The boards on the ECG appnotes are designed to pick up differential voltage from fingers on both hands. Usually, the axis of heart inclines from the center line of body. This inclination makes the differential voltage at both hands, caused by the heart electrical activity (ie. ECG). Some people, however, has straightly-positioned heart. Thin and tall shape often have this heart position. In this case, the differential voltage at both hands are reduced. Attach a wire to one of the electrode, and pick up the voltage of foot and hand.

Another consideration is contamination of electrical activity of muscles (EMG: electromyogram). EMG generates much higher voltage (around 100mV) than ECG (around 1mV). To relax the arm muscles, the testee sits in front of a desk, and places both elbows on the desk. And (s)he touches to the electrodes on the desk softly.

Tsuneo