what's wrong with my heart rate sensor?

i was looking at my arduino serial plotter. When I have my heart rate sensor plugged in with no skin contact, and pointed away from me, I have this periodic oscillation. the oscillation pattern is pretty constant, as well as the period (~2seconds).


see the wave toward the right? it looks just like a heart beat... i got all excited over nothing :frowning:

when i unplug everything i get a pretty consistent flat line. when i plug in a piece of wire i pick up noise that's pretty consistent, no oscillatory patterns with a period of 2s.

is it the circuit?

code?

void setup(){
  Serial.begin();
  pinMode(SDA, INPUT);
}

void loop(){
  int a = Serial.Read(SDA);
  Serial.prinln(a);

}

yea.. sorry to disappoint :frowning:

I thought your code could point to a 2 sec period, but that free-running code runs as fast as serial-graph can print.
Try adding some millisec delay - just to see if the mysterious pattern changes. The printbuffer is overrun ?

That code doesn't compile.

Pete

bmarconi:
i was looking at my arduino serial plotter. When I have my heart rate sensor plugged in with no skin contact, and pointed away from me, I have this periodic oscillation. the oscillation pattern is pretty constant, as well as the period (~2seconds).


see the wave toward the right? it looks just like a heart beat... i got all excited over nothing :frowning:

when i unplug everything i get a pretty consistent flat line. when i plug in a piece of wire i pick up noise that's pretty consistent, no oscillatory patterns with a period of 2s.

is it the circuit?

It is likely something else in the room.
It could even be the uP beating with the
60 cycle noise.
To be useful, you need to connect a load on the
probe inputs, similar to your body.
If it is dry contact 100K is about right.
Wet, about 5K.
Dwight

dwightthinker:
It is likely something else in the room.
It could even be the uP beating with the
60 cycle noise.
To be useful, you need to connect a load on the
probe inputs, similar to your body.
If it is dry contact 100K is about right.
Wet, about 5K.
Dwight

Dwight, you might be a little too late - it’s a 7-month old thread. Hopefully he/she has sorted it out by now.

@snehawarade1990, it’s not a good idea to dredge up old threads then reply to them. It’s very confusing. :frowning:

Oops. 7 months, I have to look back.
There was a current blank post that tricked me.
Dwight