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HP203B Schematic ( PDF Datasheet ) - HOPERF

Teilenummer HP203B
Beschreibung I2C Precision Barometer and Altimeter Sensor
Hersteller HOPERF
Logo HOPERF Logo 




Gesamt 20 Seiten
HP203B Datasheet, Funktion
HP203B
ALTIMETER
BAROMETER
THERMOMETER
Tel: +86 755 82973805 Fax: +86 755 82973550 Email: [email protected] Website: www.hoperf.com
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HP203B Datasheet, Funktion
HP203B
2. Function Descriptions
General
The HP203B is a high precision barometer and altimeter that measures the pressure and the temperature by an internal
24-bit ADC and compensates them by a patented algorithm. The fully-compensated values can be read out via the I²C
interface by external MCU. The uncompensated values can also be read out in case the user wants to perform their own
data compensation. The devices can also compute the value of altitude according to the measured pressure and
temperature.
Furthermore, the device allows the user to setup the temperature, pressure and altitude threshold values for various events.
Once the device detects that a certain event has happened, a corresponding interrupt will be generated and sent to the
external MCU. Also, multiple useful interrupt options are available to be used by the user.
 
Automatic Power-up
Once the device detects a valid VDD is externally supplied, an internal Power-On-Reset (POR) is generated and the
device will automatically enter the power-up initialization sequence. After that the device will enter the sleep state.
Normally the entire power-up sequence consumes about 400 us.
The user can scan a DEV_RDY bit in the INT_SRC register in order to know whether the device has finished its
power-up sequence. This bit appears to 1 when the sequence is done. The device stays in the sleep state unless it receives
a proper command from the external MCU. This will help to achieve minimum power consumptions.
 
Sensor Output Conversionzxza
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 6: Conversion Time VS OSR
Conversion Time (ms)
OSR
Temperature
Temperature and
Pressure (or Altitude)
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.
 
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.
Tel: +86 755 82973805 Fax: +86 755 82973550 Email: [email protected] Website: www.hoperf.com
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HP203B pdf, datenblatt
HP203B
Setup the Altitude Offset Compensation Parameter
ALT_OFF_LSB, ALT_OFF_MSB - (RW)
The two registers form the 16-bit value of ALT_OFF, which saves the altitude offset data used to compensate the altitude
calculation. The data is in 2’s complement format and the unit is in centimeter. The users need to set these registers if they
need to use the altitude computation function of the device.
Normally, the values of the local average standard atmospheric pressure (Plocal) may vary in different places around the world.
The varying range is from 1000 mbar to 1026 mbar. The device requires the user to setup the ALT_OFF to remove the offset.
The following table is provided to assist to finding the value of desired altitude offset. 
 
Plocal  has unit in mbar, Aoffset  has unit in meter 
 
 
Plocal
Aoffset
 
1000
1001
1002
111.18 102.73 94.29
1003
85.85
  Plocal
  Aoffset
1004
77.43
1005
69.02
1006
60.62
1007
52.23
  Plocal
  Aoffset
 
  Plocal
  Aoffset
1008
43.84
1012
10.41
1009
35.47
1013
2.08
1010
27.11
1014
6.24
1011
18.76
1015
14.56
  Plocal
1016
1017
1018
1019
  Aoffset
 
22.86
31.15
39.44
47.71
P  local
A  offset
 
1020
55.98
1021
64.23
1022
72.48
1023
80.71
  PA   loofcfasel t
1024
88.94
1025
97.16
1026
105.36
 
If the users find out that the value of Plocal is an integer, they can directly obtain the corresponding altitude offset value in the
above table; if the Plocal has decimal numbers and the value is larger than P1 and smaller than P2 (P1 and P2 are two adjacent
pressure values in the table), the user shall first obtain the corresponding altitude offset value A1 and A2 in the table, than
use either of the following two formulas to calculate the desired altitude offset value A: 
 
A = A1  + 8.326 x (Plocal   P1), or A = A2  ‐ 8.326 x (P2   Plocal) 
 
For example, the Plocal  is 1016.4 mbar, which is between 1016 mbar (P1) and 1017 mbar (P2). Looking up the table, A1  is 22.86 m 
and A2  is 31.15 m. Thus: 
 
A = 22.86 + 8.326 x (1016.4 – 1016) = 26.19 m, or A = 31.15 - 8.326 x (1017 – 1016.4) = 26.15 m
 
Either of the results is acceptable. After obtaining the value of A, no matter by looking up the table directly or by
calculation, the user shall multiply the A by 100 in order to convert the unit from meter to centimeter.
Finally, convert the result to a 2’s complement number to obtain ALT_OFF, and fill it into the two registers. The following
table shows 2 examples with the calculated altitude offsets and their corresponding values to fill into the two registers.
 
Example:
  Offset
 
 
 
50.02 m
-100.05 m
 
Hex Value
0x138A
0XD8EB
ALT_OFF_MSB
0x13
0xD8
ALT_OFF_LSB
0x8A
0xEB
Tel: +86 755 82973805 Fax: +86 755 82973550 Email: [email protected] Website: www.hoperf.com
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