I want to use a ATMega 16 to measure voltage and current on an Alternator test bench and Log the data.
My first problem after doing some calculations is that I won't be able to use the ADC of the AVR to measure the voltage. I need it to display/record up to 40V DC with a resolution of 0.1V. With the 10bit ADC this doesn't seem possible. High speed is not required. Is there another way of doing this or do I have to use an external ADC with higher resolution?
Second problem is that the test bench already has a current shunt being used by a gauge to display the current. The current shunt is 200A 50mV deflection. What would be the best way to handle this? Feed it through an OP-Amp to amplify the voltage or just feed it into one of the AVR ADC pins and use the micro to do the calculations. I thought the voltage might be a bit low (50mV).
The other thing I had a question about is what is going to happen to the output of the current shunt if I exceed 200A? Besides probably damaging the shunt, will the voltage exceed 50mV or is that the maximum output. I would think that it would still increase?
Any help with this would be appreciated.