DA5534C_003.doc

June 16th, 2008

10

0005534C1175 ECN1118

Example:

Word1, Word2, Word3 and Word4 (4x16 Bit)

D1 = 17000

D2 = 22500

Start

Convert calibration data into coefficients:

(see bit pattern of Word1-Word4)

Read calibration data (factory calibrated) from

PROM of MS5534C

Read digital pressure value from MS5534C

D1 (16 Bit)

Read digital temperature value from MS5534C

Display pressure and temperature value

Basic equations:

Calculate calibration temperature

UT1 = 8*C5+20224

Calculate temperature compensated pressure

Difference between actual temperature and reference

temperature:

dT = D2 - UT1

Actual temperature:

TEMP = 200 + dT*(C6+50)/2

10

(0.1°C resolution)

Calculate actual temperature

D2 (16 Bit)

SENST1

OFFT1

TCS

TCO

TEMPSENS

C1: Pressure sensitivity

(15 Bit)

C2: Pressure offset

(12 Bit)

C3: Temperature coefficient of pressure sensitivity (10 Bit)

C4: Temperature coefficient of pressure offset

(10 Bit)

C5: Reference temperature

(11 Bit)

C6: Temperature coefficient of the temperature

(6 Bit)

calculated results)

Word1 = 50426

Word2 = 9504

Word3 = 48029

Word4 = 55028

C1 = 25213

C2 = 1908

C3 =

859

C4 =

750

C5 =

148

C6 =

32

TEMP(D2) = 20°+dT(D2)*TEMPSENS

Offset at actual temperature:

OFF = C2*4 + ((C4-512)*dT)/2

12

Sensitivity at actual temperature:

SENS = C1 + (C3*dT)/2

X = (SENS * (D1-7168))/2

Temperature compensated pressure:

P = X*10/2

(0.1mbar resolution)

OFF(D2) = OFFT1+TCO*dT(D2)

SENS(D2) = SENST1+TCS*dT(D2)

P(D1,D2) = D1*SENS(D2)-OFF(D2)

dT

= 1092

TEMP = 287

= 28.7 °C

OFF

= 7695

SENS = 50705

X

= 22732

P

= 9603

= 960.3 mbar

Fig. 3: Flow chart for pressure and temperature reading and software compensation.

NOTES

1) Readings of D2 can be done less frequently, but the display will be less stable in this case.

2) For a stable display of 0.1 mbar resolution, it is recommended to display the average of 8 subsequent

pressure values.