Re: Analog to digital converter - clock prescaler tests, obsevations and questions

Projects Programming
1

Hi,

I need to do the Analog to Digital conversion with a Sampling frequency of 100 hertz for a signal ranging from 0-5V .From the data sheet I understood it is not possible to get this sampling frequency by setting the prescalar.Can any one suggest a method for getting this frequency using arduino UNO?

2

Where does it say in the datasheet that you can't sample 100 Hz?

3

You can do around 10000 ADC conversions per second, using the default settings. More if you tweak the prescaler. How does this not let you handle 100 Hz?

4

Thank you for your response.What I meant is that the minimum sampling frequency that we can get by setting the prescalar is 16/128/13=9.6 khz.My expected sampling frequency is 100 hertz.So I am asking about how to get that sampling frequency.

5

Sample less often?

6

512 samples are used since I am using 512 POINT fft.

7

Bisni,

The ADC can sample at 9.6kSPS at its lowest rate, this doesn't mean you have to use all the data.

For lower speeds you want time driven conversion.

The simplest way will be create an interrupt which fires at 100Hz, and do the ADC read in the interrupt handler.

Even if you had a continuous ADC, reducing the sampling rate, decimation, is the same as simply ignoring some of your results!

8

Thank you for the reply.I tried it with delay( ).Still the data will lose?