Well, not in a meteorological sense.
The baro sensor sends out 11 coefficients set at the factory, most having something to do with temperature and other calibration values, then you have a raw signal relating to pressure and temperature.
You have to run all those values that through a set of equations to get the "absolute" or "station" pressure. This is done outside of the bridge, likely due to it not have much in the way of computational ability.
The code ends up looking something like this:Code: [Select]$c1 = hex ($c1);
$c2 = hex ($c2);
$c3 = hex ($c3);
$c4 = hex ($c4);
$c5 = hex ($c5);
$c6 = hex ($c6);
$c7 = hex ($c7);
$a = hex ($a);
$b = hex ($b);
$c = hex ($c);
$d = hex ($d);
$pr = hex ($pr);
$tr = hex ($tr);
$d1 = $pr;
$d2 = $tr;
if ($d2 >= $c5)
{
$dut = $d2-$c5-(($d2-$c5)/2**7) * (($d2-$c5)/2**7)*$a/2**$c;
}
else
{
$dut = $d2-$c5-(($d2-$c5)/2**7) * (($d2-$c5)/2**7)*$b/2**$c;
};
$off = ($c2 + ($c4 - 1024) * $dut / 2**14) * 4;
$sens = $c1 + $c3 * $dut / 2**10;
$x = $sens * ($d1 - 7168) / 2**14 - $off;
$p = $x * 10 / 2**5 + $c7;
$t = 250 + $dut*$c6/2**16-$dut/2**$d;
The temperature is the $t value, but you have to divide it by 10 to get a proper Celsius value.
These equations are supplied by the manufacturer of the baro sensor. Baro sensors from other manufacturers and models will likely be different, so these equations might not work for the consoles. I know they don't work for the 2032c console, for example.
Note this just gets you "absolute" or "station" pressure. Further work is needed to reduce it to MSL or Altimeter, or whatever. I usually just apply a fixed offset based on the local airport reading.
Thanks for taking the time to explain that. I guess if there is no actual sensor in the bridge then it must be a generated value.
It seems to me that the Acurite "system" is rather complicated. It has to deal with many different setups. I can envisage different sensors, sending in data through either a console using their software or through a bridge.