Senior Member
Joined: 17/11/2011
Location: AustraliaPosts: 231
| Posted: 10:16am 13 Mar 2012 |
What I was asking if both forumulas "matched" in format the formuluas by sparkfun and by Bosch?
The weather algorithm produced 0 differential? Looking at the weather calculation, I had to insert a "fixed" value for the altitude and replaced BMP085_Pa with the pressure at sea level eg 101325 Pa. by doing so, the "epressure_Pa" seems to always stay around at 101325. The formula seems "not to change" but it gives the needed diff. "leg" for the epressure_Pa difference.
SUB cal_Weather
' algorithm fix - the differential was always zero because the altitude was variable not fixed.
' epressure calculation should have sealevel Pa!
Local ePressure_Pa, weatherDiff, BMP085_Pa, cal_constant, fixed_user_altitude_M
cal_BMP085_Pressure ' get pressure (in millibars/hectorPascals)
'cal_Altitude <--- do not use - for ref. only
fixed_user_altitude_M = 273.1 ' <-----<<<<< Local user altitude in meters
cal_constant = 0 ' 0 millibars - for calbibration if needed.
ePressure_Pa = 101325 * (1.0 - ((fixed_user_altitude_M / 44330)^ 5.255)) ' In meters and Pascals
BMP085_Pa = (BMP085_P - cal_constant) * 100 ' Convert to Pascals with cal constant
weatherDiff = BMP085_Pa - ePressure_pa
? "BMP085 Weather BMP085_Pa = ",BMP085_Pa
? "BMP085 Weather ePressure Pa = ",ePressure_Pa
? "BMP085 Weather Diff. Pa = ",weatherDiff
if(weatherDiff > 250) then
?"Sunny!"
ELSEIF ((weatherDiff <= 250) OR (weatherDiff >= -250)) THEN
?"Partly Cloudy"
ELSEIF if (weatherDiff > -250) THEN
?"Rain"
ENDIF
END SUB
' algorithm fix - the differential was always zero because the altitude was variable not fixed.
' epressure calculation should have sealevel Pa!
Local ePressure_Pa, weatherDiff, BMP085_Pa, cal_constant, fixed_user_altitude_M
cal_BMP085_Pressure ' get pressure (in millibars/hectorPascals)
'cal_Altitude <--- do not use - for ref. only
fixed_user_altitude_M = 273.1 ' <-----<<<<< Local user altitude in meters
cal_constant = 0 ' 0 millibars - for calbibration if needed.
ePressure_Pa = 101325 * (1.0 - ((fixed_user_altitude_M / 44330)^ 5.255)) ' In meters and Pascals
BMP085_Pa = (BMP085_P - cal_constant) * 100 ' Convert to Pascals with cal constant
weatherDiff = BMP085_Pa - ePressure_pa
? "BMP085 Weather BMP085_Pa = ",BMP085_Pa
? "BMP085 Weather ePressure Pa = ",ePressure_Pa
? "BMP085 Weather Diff. Pa = ",weatherDiff
if(weatherDiff > 250) then
?"Sunny!"
ELSEIF ((weatherDiff <= 250) OR (weatherDiff >= -250)) THEN
?"Partly Cloudy"
ELSEIF if (weatherDiff > -250) THEN
?"Rain"
ENDIF
END SUB
Are you struggling with free memory?
Yes, but the workaround is to run "blocks of code" from the SD drive which has 16 GB.
