an analog circuit's output is given to an ADC pin of the microcontroller , does the current flow to the pin too ? I have some very fundamental doubts, It would be a great help if anyone can clear it ?
Thank you.
Thank you.
an analog circuit's output is given to an ADC pin of the microcontroller , does the current flow to the pin too ? I have some very fundamental doubts, It would be a great help if anyone can clear it ?
Thank you.
Kapp simply explained the simple basics of electricity (Ohm's Law) that was not taught in India.
Kapp touched on an excellent point that most (if not all) μcu's have as a limitation of their ADC port. The input pin has a switched capacitor on it - thus if the input impedance is too high (i.e. - using high resistances to reduce current coming into the pin) there will be a delay in acquiring the voltage as the cap charges up. Too long of an RC delay and the timing maybe altered. Some pic's have a max impedance of 2.5k Ω's!!An ADC's input has a finite resistance (less than infinity). Do the math.
It also has some capacitance which needs to be charged and discharged by the input voltage.
I think I did understand the question. I could have replied simply with 'yes'.I think Kapp is only an engineer and doesn't understand simple questions.He only sees complicated solutions.
[/QUOTE]Kapp touched on an excellent point that most (if not all) μcu's have as a limitation of their ADC port. The input pin has a switched capacitor on it - thus if the input impedance is too high (i.e. - using high resistances to reduce current coming into the pin) there will be a delay in acquiring the voltage as the cap charges up. Too long of an RC delay and the timing maybe altered. Some pic's have a max impedance of 2.5k Ω's!!
More information is needed to discuss possible solutions. To give some food for thought, you may isolate the ADC's limited impedance with a log amp.
I think I did understand the question. I could have replied simply with 'yes'.
What help would that have been to the op in clarifying his doubts?
With reference to 'only an engineer': A good engineer imho not just solves a problem - this any tinkerer can do given enough time. A good one at least tries to understand the issue at hand (he may not always succeed) to avoid the same issue in the future.
And yes, call me Harald![]()
Yes you were quite correct in your answer. You could have answered in French or German and been quite correct.