DataSheet

HP203B

3.4 Sensor Output Conversion

For each pressure measurement, the temperature is always being measured prior to pressure

measurement automatically, while the temperature measurement can be done individually. The

conversion results are stored into the embedded memories that retain their contents when the device

is in the sleep state.

The conversion time depends on the value of the OSR parameter sent to the device within the

ADC_CVT command. Six options of the OSR can be chosen, range from 128, 256 … to 4096. The

below table shows the conversion time according to the different values of OSR:

Table 5: Conversion Time VS OSR

OSR

Conversion Time (ms)

Temperature

Temperature and

Pressure (or ltitude)

128

2.1

4.1

256

4.1

8.2

512

8.2

16.4

1024

16.4

32.8

2048

32.8

65.6

4096

65.6

131.1

The higher OSR will normally achieve higher measuring precision, but consume more time and

power.

The conversion results can be compensated or uncompensated. The user can enable/disable

the compensation by setting the PARA register before performing the conversions.

3.5 Altitude Computation

The device can compute the altitude according to the measured pressure and temperature. The

altitude value is updated and available to read as soon as the temperature and pressure

measurement is done.

4. Access Modes & Commands

4.1 Operation Flow

During each power-up/reset cycle, the device will only perform one calibration. After that it will enter

the SLEEP state waiting for any incoming commands. It will take actions after receiving different

proper commands, and re-enters the SLEEP state when it finishes the jobs.

4.2 Command

The Command Set (Table 6) allows the user to control the device to perform the measuring, results

reading and the miscellaneous normal operations.

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