[En-Nut-Discussion] AD conversion resolution?

[Gerwin Voorsluijs]

Hi Kathy,

You mean it could be noise? That would not explain why I don't see such 
jumps on my voltmeter, nor does it explain why I see this behaviour over 
a number of sweeps. Btw I use the internal reference voltage on the 
Ethernut.

In the mailing list I saw that you are also using the ADC function of 
the Ethernut and I was wondering if you could look at the results you 
are getting to see if maybe I'm unlucky and my Ethernut is broken?
I know that on the total range of the 10bit ADC (1024 values) a jump of 
50 is not that big (roughly 5% ), but for what I want to use it for, it 
is vital.

Cheers,

Gerwin

Kathy Quinlan wrote:
> How do you know your powersupply is not "jumping" what is the ref 
> voltage ????
> 
> What is the voltage going to ADC ????
> 
> If the input is just a pot between VCC and Gnd, could it be a secsion of 
> contamination etc.
> 
> Regards,
> 
> Kat.
> 
> Gerwin Voorsluijs wrote:
> 
>> Hi,
>>
>> Maybe I didn't make myself clear, but I don't need to know if the ADC 
>> is linear or not, I want to know why I don't get certain values when 
>> I'm sure they have to be in there (voltage is very slowly varying!) 
>> Consider the following short int values that are in my data (and their 
>> binary counterparts): isn't it odd that there is no values in the 
>> range 256-303? That was btw the way I noticed there was something 
>> wrong: the value would stay on 255 for a very long time while I was 
>> doing my voltage sweep.
>>
>>  156 010011100
>>  158 010011110
>>  159 010011111
>>  176 010110000
>>  177 010110001
>>  184 010111000
>>  188 010111100
>>  192 011000000
>>  193 011000001
>>  195 011000011
>>  199 011000111
>>  206 011001110
>>  207 011001111
>>  224 011100000
>>  225 011100001
>>  227 011100011
>>  231 011100111
>>  240 011110000
>>  241 011110001
>>  248 011111000
>>  252 011111100
>>  254 011111110
>>  255 011111111
>>  304 100110000
>>  312 100111000
>>  316 100111100
>>  318 100111110
>>  319 100111111
>>  327 101000111
>>  335 101001111
>>  348 101011100
>>  352 101100000
>>
>> Cheers,
>>
>> Gerwin
> 
> 
> 
>