Voltage reading and displaying advice

[dariods8474]

I have 200 mSec timing available in my code. I need to take a voltage reading and display it on the LCD. I have read that it's a good practice to take multiple readings, average it and then display it. I have multiple options and I would like advice on which option should be used.

1. Take 20 readings every 200ms, average it (divide by 20) and display on lcd
2. Take 1 reading every 200ms for 1 sec(5 readings/sec), average it (divide by 5)and display on lcd
3. Take 20 readings in 200ms, average it. Do it 5 times. Add the readings, divide the total by 5 then display it every 1 second on lcd.

[DVDdoug]

It depends on the noise but since noise is generally random the timing of the 20 reads should not matter.

If the voltage is "rock solid" (no variation/noise) you don't need to take multiple readings.

It is a good idea to hold the display (maybe for more than 200ms) so you can read it and "make sense" of the reading.

[gcjr]

you can use leaky integration to average each 200 msec reading against the current average. there will be some delay when there are significant changes

avg += (samp - avg) / N;

red N=4
orange N=8
yellow N=16

[dariods8474]

What is N?

[gcjr]

the filter coefficient, very comparable to an RC time constant.

the output will be close to 1 for a step input of 1, after 3 N iterations