ADC Accuracy on the STM8S208

[DRanc]

I'm using the STM8S208 for a project that requires use of 11 ADC channels. I've noticed that the measured readings are inaccurate. Is there something I can do in my circuitry to make it more accurate? Or should I just buy a dedicated ADC IC?

I have a 5V reference, filtered from the board 5V supply with a ferrite bead.

My ADC settings: fCPU/2 prescaler, Schmitt trigger disabled

Test circuit using a 10k pot to generate a variable voltage. Measuring it with a DMM and tying the voltage to ADC2_CHANNEL_9

Input voltage on channel, measured by DMM - 2.316V

Range of ADC measurements - 2.200V --> 2.356V

Input voltage on channel, measured by DMM - 0.656V

Range of ADC measurements - 0.468V --> 0.720V

Input voltage on channel, measured by DMM - 4.548V

Range of ADC measurements - 3.376V --> 4.000V

[TA1]

Hi

Actually I wrote very long answer because measurument accuarcy depends on too many parameters. However I realized your problem it not a small issue. 4.548V shouldn't be measured 3,3 or 4 V. This is not error. This is something else and you cannot say it is measurument error. Error should be maksimum 5%. Here 27%. It is too much. I think it is not about ADC or microcontroller. I think you have very basic problem.

Regards