I have three AD8232 modules from Sparkfun, conforming the example from Figure 66 page 28 of the datasheet.
I have the module connected to 3V (from 2 AA-cells) and observing the output with a battery powered oscilloscope, while I have the electrodes connected to my body.
Unfortunately I don't see anything close to an ECG-signal. In my setup channel 1 from my oscilloscope is connected to OUT and channel 2 is connected to LO-.
When all three leads are connected I see the following signals:
I have a quiet clean 1.5V output signal, and seeing some peaks on LO- all 20ms, which correlates to 50Hz (our Mains electricity). As my setup runs all from battery, this 50Hz looks like received from my body as antenna.
But I never expected to see 50Hz noise on LO-/LO+, I would have expected to some 50Hz noise in the ECG signal.
When I now disconnect the RA-lead, I see the following signals:
The output voltage drops to 0V, while LO- goes high to 3V, but now with some spikes all 20ms to 0V.
Next step I disconnect the driven right-leg lead, and have both arms connected:
Now I see a 50HZ square output on LO-, while outpus is still 0V
Next combination is RA and RL connected, while LA is disconnected:
Now the output signal jumps up to 3V, while again LO- is 0V, with spikes to 3V all 20ms.
All three of my boards behave the same. From my standpoint it looks really weird, especially, why the lead-Off-detection gives such signals. And output gives no signal at all.
Does anyone have some ideas?