----- Original Message -----
From: "Jens Boos" <[email protected]>
To: "neonixie-l" <[email protected]>
Sent: Thursday, October 14, 2010 6:46 PM
Subject: [neonixie-l] Re: Weird MAX1242 ADC behaviour
And the c source:
http://www.jb-electronics.de/tmp/voltmeter_source.c
static int TimeCounter, WertADC, oldADC, Spannung, mean;
// calculate mean
mean_counter++;
mean += WertADC * (0.3215 + 0.004); // 0.3215 out of calculation,
additional term is tweaked
if (mean_counter >= 50) {
Spannung = mean / mean_counter;
mean = 0;
mean_counter = 0;
}
WertADC is an integer. Then you multiply by a float constant
(0.3215+0.004), which gives an
internal float result. This float is then rounded downwards to an integer
again (mean).
Perhaps you should declare mean as a float, not an int.
static float mean;
Or something like this:
mean += WertADC;
and
if (mean_counter >= 10) {
Spannung = (mean * 0.3215) / mean_counter) ;
Just to save a bit of time on all those floating point calculations...
Best wishes,
Frank
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