Re: [avr-chat] Comparisson with negative values

[John]

 Many thanks for all the replies.

My project is rolling along again for the moment.

 I went to a night class in C programming a few years ago
 but seam to have forgotten a few things.

I am reading out values to a computer screen via serial link
in the manner of  largedemo by replacing "new" with whatever
I want to read out. Even with error declared as unsigned uint16_t
I had the same positive and negative readout as with error declared 
as int_16t. I will have to think why. 

As for the volatile declaration I just used the idea from largedemo.
Some of the variables there are declared as volatile. Looking up
the meaning of volatile in C programming I am given :-
              "not stored in machine register"
but where it is stored and what it means in terms of avr programming 
I  really dont know.

At the moment I am using two potentiometers to simulate real word 
inputs. I am buffering the internal 2.56V reference to supply the 
potentiometers and using same internal reference for adc.
It is atmega8 with 10 bit converssion so my potentiometers read
out 0-1023 and I dont have the overflow type of problem just at the
moment.

I am working towards a controller like PID descibed on Atmels site
alternatively a fuzzy one.

John