Can't read negative voltage values

[aeytr]

Hi,

I built an ECG circuit that works fine. Now I want to read ECG signal via arduino analog pins(I m usingpro mini/5V/16Mhz). The problem is I cant read negative voltage values. I tried some methods but none of them worked.

Can you please help?

Thanks.
Regards.

Ali Emre

 

[Audioguru]

Simply apply a positive DC offset voltage to the signal so that it never goes negative unless the signal strength increases.

 

[BradtheRad]

Simple way to lift negative voltage into the positive:

 

[KlausST]

Hi,

I think ECG signals need no DC measurement, therefore a capacitive coupling and biassing to ADC_VRef/2 is a solution.

Klaus