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[Sonu Saini]

hi

I m using a PIC24 and need to measure the voltage across a battery as well as the current into it.

The voltage across the battery is done, A/D input at +ve, PIC ground to negative. The problem comes when trying to measure current in, for which I plan to measure the voltage drop across a low value resistor.

As far as I can figure, my PIC will only measure positive voltage differences.

thanks

[GANEEV SINGH]

Hi there

You are doing it absolutely right by measuring the voltage drop across a low value resistor. Now this value will help you measure current using ohm's law:

V=I*R; here, R and V are known to us thus, I can be easily calculated. Make sure to conver the ADC value you get back to its voltage reading by some mathematical operation and then use this V to calculate I.

Hope this helps  

[Ashutosh Bhatt]

current sensor modules are also readily available

or you can build simple I to V convertor using opamp – 741

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