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Re: [avr-chat] Comparisson with negative values
From: |
John |
Subject: |
Re: [avr-chat] Comparisson with negative values |
Date: |
Tue, 20 Nov 2007 13:28:29 +0100 |
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