DC Voltage measurment with atmega16

[alisarhangpour]

I'm using Atmega16 and I'm going to measure up to 6 different analog signals with its ADC. The problem is, on of these volatges has no common ground with the micro controller and is a DC voltage up to 600V. A precision of around 1V is just enough. What can I do about this? A solution might be to use a seperate ADC chip and send its results to micro but:1.it takes more than 8 pins of the micro, 2.Probably I have to use an array of optocouplers to solve the oncommon ground problem, 3.I might be able to use a serial interface between ADC chip and micro, but it appears to be unnecessarily complicated and time consuming.
Any ideas?
Thank you.

 

[Leftyretro]

I'm using Atmega16 and I'm going to measure up to 6 different analog signals with its ADC. The problem is, on of these volatges has no common ground with the micro controller . A precision of around 1V is just enough. What can I do about this? A solution might be to use a seperate ADC chip and send its results to micro but:1.it takes more than 8 pins of the micro, 2.Probably I have to use an array of optocouplers to solve the oncommon ground problem, 3.I might be able to use a serial interface between ADC chip and micro, but it appears to be unnecessarily complicated and time consuming.
Any ideas?
Thank you.

"no common ground " = you will require a differential input circuit & op amp for this measurement channel. Research the term 'instrumentation opamp' to see examples of how to measure a signal without a common connection.


"and is a DC voltage up to 600V. A precision of around 1V is just enough." =

You will have to design a 100/1 resistor input attenuator to convert a 0-600 to a 0-6 volt signal. Then utilizing a differential input op amp buffer you should be able to process the measurement. Then in your software you will have to remember to multiply this digital value by 100 to maintain it's origninal magnitude.

Good Luck

Lefty

 

[alisarhangpour]

Thank you Lefty, I'm actually astonished by how quickly someone posted a reply to my question. I'll try your solution.
Thank you again.