noise in ADC conversion

I’m trying to use ADC (from RCM4300 module), I don’t have problems to get analog voltage in LN0-LN7 pins, with a range from 0 to 2 volts, but unfortunately we have a lot of noise in the sampled values.
I have 2 questions:

  1. Is there a way to minimize the noise in the ADC?
  2. I do not use the VREF pin, so, is necessary connect it to ground?, whats is the VREF function?

A/D converter reference voltage (RCM4300 only) It might be a good idea to review the User manual located at

I also suggest try running some of the sample programs usign the protoboard

You can minimize the noise in the ADC in the software by using a multiple reading average and a condition not to update the reading unless the count varies past what would be assumed to be noise.

In hardware you can use bypass capacitors. Any good hardware book can give you some tips on noise reduction.

Also, follow the suggestions in the user manual.