how do I minimize ADC clock freq via a register?

Using Arduino Programming Questions
1

I see from the data sheet of the micro controller that ADPS2-0 affect this, but I am not sure how in code to do this.

I'll continue to scour the forums but your help is appreciated

Thanks

2

The ADPSn bits are part of the ADCSRA register. You can set them using code like the following -

// ADC clock prescaler 8
ADCSRA |= (1 << ADPS1) | (1 << ADPS0);

That's untested but it should work. The exact combination of bits that you turn on affects the pre scaler, but you know that already from reading the data sheet :slight_smile:

Look up bit wise operations/bitmath for more information about what is going on, or search for something like "AVR set bit"

3

a.d:
The ADPSn bits are part of the ADCSRA register. You can set them using code like the following -

// ADC clock prescaler 8

ADCSRA |= (1 << ADPS1) | (1 << ADPS0);




That's untested but it should work. The exact combination of bits that you turn on affects the pre scaler, but you know that already from reading the data sheet :)

Look up bit wise operations/bitmath for more information about what is going on, or search for something like "AVR set bit"

Thanks!

4

Other than the prescaler for the ADC, is there another register I can write to so that I can slow the ADC clock even more?

Thanks

5

Why do you want to slow it? That will make the conversion time longer, and may affect the accuracy of the sample & hold circuit that is charged up prior to making the conversion.

6

CrossRoads:
Why do you want to slow it? That will make the conversion time longer, and may affect the accuracy of the sample & hold circuit that is charged up prior to making the conversion.

I need to perform DSP on an audio signal and want the bins to have a small frequency span for better granularity. This is for a spectrum analyzer display.