Mega 2560 ADC reads near zero volts at random times!

I am using a MEGA 2560 because it has 16 analog inputs. I am using all 16 analog inputs that output to a Raspberry Pi unit via I2C. I am seeing noise that appears to go near 5V for 1 or 2 readings, and also 0V for a very brief 1-2 readings. The MEGA unit also does some addition and division math. The signals coming into the MEGA unit go through low-pass filters at .17Hz. These filters all have capacitors on them making it impossible for the signal to briefly go to 0V. Here is the read out of one of the analog inputs:

D = 510
D = 510
D = 510
D = 510
D = 510
D = 509
D = 509
D = 1
D = 1
D = 511
D = 511
D = 511
D = 511
D = 507
D = 507
D = 507

IS THIS INTERNAL NOISE?

WHAT IS CAUSING THIS? HOW CAN I MAKE IT STOP?

PLEASE HELP.

Why are you shouting? - is the bigger question right now.

First point on that page:

When typing never write in all capital letters.
That is shouting. People don't like it when you shout at them in person. And they sure don't like it when you shout at them on the net.

How is your reference voltage managed on analog pins? Could you have noise on the power supply?

If those are compatible with your reading values, Have you tried with INTERNAL1V1 (built-in 1.1V reference) or
INTERNAL2V56 (built-in 2.56V reference) for Arduino Mega only?

Hi,
Welcome to the forum.

If you continuously read one input ONLY, and no others, does the noise persist?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
How have you got the gnds connected to the 16 analog sources?
Even if it has only one of your 16 analog inputs shown, how are you powering the arduino?

Thanks.. Tom.. :slight_smile: