inaccuracy of pin readings

Projects General Guidance
1

over the last few projects i have had problems reading sensors and problems reading signals on many projects. i have purchased boards from many different places. i have ordered very cheep boards from china. i have ordered from random american suppliers.

ive had problems of analog readings bouncing around far more than they should.

does anyone else have experience with "cheap" boards?

has anyone else experienced this sort of problem?

or is this more likely due to other things like burnt boards or pins /poor project design?

2

Clone boards are usually fine.

Without any details ( drawings, code, photos etc) ........ hard to say.

3

The ATmega chip should be stable within +/- 1 bit. You can test that with a [u]voltage divider[/u] connected to Vcc.

You can get bigger variations if the analog signal or the reference is unstable. Or, if you have a high-impedance source the connecting wires can pick-up noise, especially if the wires are long and/or unshielded.

4

Also you can get varying readings by poor layout or interference generating components like motors. Also poor power supply decoupling can be to blame.

5

Bear in mind too , by default the analog reading uses the chip supply voltage (5v) as a reference , using the internal reference may improve matters

6

taterking:
poor project design?

That's my number-one suggestion.

Also, the problem is in the code you didn't post.