It may be better to use a 5V plug-in power supply instead of the item from Farnell and to use a 3.3V voltage regulator such as this example. Then you will simply need 2 capacitors and a barrel socket. This would avoid hazardous mains voltage.

I tried running the example program of peripherals/adc and found that each conversion took about 40us. That mean, a sampling speed of 25K Samples/second. Is that really possible or I am being mistaken? As reported in an earlier post in this thread, I have measured 9.5μs (including the time taken to...

Could be induced voltage on the connection between pot and pin. Put a 100nF cap as close as possible to pin and ground and use exponential filtering in software. Thanks, but as I get readings from a potentiometer on an Arduino Micro that only vary between adjacent values, I don't think induced volt...

For realy serious ADC performance analyzes you should use some precision voltage reference source, not the potentiometer which can introduce errors by itself. Thanks for your comment. Voltmeter readings indicate that the ADC input voltage is stable to within 1mV over several hours. With no delay in...

The bottom line is that I don't know what to expect for noise with a measurement like you are doing. For a good ADC with constant input voltage we should expect successive digital readings to either remain constant or to waver between two adjacent digital values. The digital readings can reasonably...

How are you powering the pot? Are you using a separate regulated supply? I also see a lot of noise on the ADC. So what you are seeing (<3%) isn't that bad compared to what I'm seeing. Although I'm reading a sensor with a lot of amplification. I'm powering the development board and pot by a 5V switc...

fly135 wrote:Try putting a delay between readings.

Thanks for the suggestion. With 10ms in the loop, I still get a similar spread of rogue readings.

I have removed similar header pins from an Arduino one at a time using a soldering iron. The plastic melts sufficiently. I was holding the Arduino in a small vice along its sides and pulling each pin out with pliers.

Alternatively, shorten the pins using side (diagonal) cutters.

Having noticed a few ADC readings outside the well-known 'noise', I decided to plot a histogram of readings . . . ADC-histogram1.png The x-axis is for readings from 1960 to 2070, not as labelled. The mode (most frequent reading) is at a 2015 so is close to middle of the ADC's range (0 to 4095). The ...

There's an alternative Arduino-ESP32 'Wire' library here that is supposed to be better:
https://github.com/stickbreaker/arduino ... aries/Wire