AVR-Chat

Hi folks,

I am playing with some ADC stuff, but (Damn it Jim,) I am a programmer,
not an electronics whiz.

I am using Mega8's in PDIP packages, using the internal oscillator
(running at 8Mhz).

The chip is setup to use the internal reference 2.56V and a prescaler of
64 (giving 125.000 kHz ADC clock freq).

I have .1uf smoothing caps on the right next to the chips between VCC
and GND.

I have .1uf caps between AVCC and GND, and also between AREF and GND.
Once again right next to the IC.

The analogue source is 100K linear POTs.

The pots are 3pin pots with pin 1 connected to GND, pin 3 to AREF and
pin 2 to the ADCn.

The priority is on smooth and non-fluctuating/steady signal as opposed
to an 'accurate' signal. It is for joystick inputs, and the pots are
connected to things like throttles and flight yokes, rudder pedals.

The Mega8 iterates through the 6 ADC channels.

I have implemented software smoothing within the chip, but the raw
hardware signal is bouncing around by up to 4 bits.

My question are these: What else can I do or should I do to get a
'smooth signal'?

- Should I be using an external clock source?

- Should I be using VCC as my AREF?
- Should I be using something other than the Int.Ref 2.56v for AREF?
- What would be regarded as a 'smooth' VCC or AREF? My VCC at the moment
is fluctuating by about 20mV according to the scope.

Any comments, tips suggestions or advice would be most welcome.

Kind Regards,
Stuart Whelan

Recursion: See Recursion.