Hope RF

HP02S

BAROMETER MODULE

2011-6-8

Version: 1.4

3

Pressure and Temperature Measurement

The main function of HP02S system is to convert the uncompensated pressure and

temperature signal from a pressure sensor. After the conversion, the following two values

can be obtained:

. measured temperature

“T1”

. measured pressure

“D1”

As the sensor is strongly temperature dependent, it is necessary to compensate for these

effects. Therefore 5 sensor-specific coefficients are stored on the HP02S at our

manufacturing facility, and they allow an accurate software compensation in the

application.

The 5 coefficients are:

. “D0”: Offset of pressure coefficient.

. “T0”: Offset temperature.

. “P0”: Offset fine tuning of pressure.

. “S”: Temperature coefficient of sensitivity.

. “C”: Constant parameter for each sensor.

Note: Make sure to pull low XCLR before start to Read these coefficients or the data read

out is probably incorrect

Pressure and Temperature Calculation:

Step 1: (calculate offset, sensitivity and final pressure value)

dUP=D1-D0

dUT=(29*(T1-T0)/50-(T1-T0)^2/76666)*S/C

P=P0+100*(dUP+dUT)/S

Example:

D0=41058

T0=32819

P0=10143

S=294

C=320

D1=42920

T1=29889

dUP = 42920-41058 =1862

dUT=

(29*(29889-32819)/50-(29889-32819)^2/76666)*294/320=-

1664

P=10143+100*(1862-1664)/294=10210=1021.0hpa