Download Datasheet

LPS25HB
MEMS pressure sensor: 260-1260 hPa absolute
digital output barometer
Datasheet - production data
Applications
HLGA-10L
(2.5 x 2.5 x 0.76 mm typ.)
•
Altimeter and barometer for portable devices
•
Enhanced GPS applications
•
Weather station equipment
•
Wearable devices
Description
Features
• 260 to 1260 hPa absolute pressure range
• High-resolution mode: 0.01 hPa RMS
• Low-power consumption
– Low-resolution mode: 4 µA
– Low current & noise mode with FIFO:
4.5 µA
• High overpressure capability: 20x full scale
• Embedded temperature compensation
• 24-bit pressure data output
• ODR from 1 Hz to 25 Hz
• SPI and I2C interfaces
The LPS25HB is a piezoresistive absolute
pressure sensor which functions as a digital
output barometer. The device comprises a
sensing element and an IC interface which
communicates through I2C or SPI from the
sensing element to the application.
The sensing element, which detects absolute
pressure, consists of a suspended membrane
manufactured using a dedicated process
developed by ST.
The LPS25HB is available in a full-mold, holed
LGA package (HLGA). It is guaranteed to operate
over a temperature range extending from -30 to
+105 °C. The package is holed to allow external
pressure to reach the sensing element.
• Embedded FIFO
• Interrupt functions: Data Ready, FIFO flags,
pressure thresholds
• Supply voltage: 1.7 to 3.6 V
• High shock survivability: 10,000 g
• ECOPACK® lead-free compliant
Table 1. Device summary
Order code
Temperature range [°C]
Package
Packing
LPS25HBTR
-30 to +105 °C
HLGA-10L
Tape and reel
June 2016
This is information on a product in full production.
DocID027112 Rev 3
1/40
www.st.com
Contents
LPS25HB
Contents
1
Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
Mechanical and electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1
Mechanical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3
Communication interface characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4
3
4
5
SPI - serial peripheral interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.2
I2C - inter-IC control interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1
Sensing element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2
I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3
Factory calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
FIFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1
Bypass mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2
FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3
Stream mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.4
Stream-to-FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5
Bypass-to-Stream mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6
FIFO Mean mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.7
Bypass-to-FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.8
Retrieving data from FIFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1
6
2.3.1
Soldering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Digital interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1
I2C serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2
I2C serial interface (CS = High) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2.1
6.3
2/40
I2C operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
SPI bus interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
DocID027112 Rev 3
LPS25HB
Contents
6.3.1
SPI read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.3.2
SPI write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.3.3
SPI read in 3-wire mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7
Register mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8
Register description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.1
REF_P_XL (08h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.2
REF_P_L (09h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.3
REF_P_H (0Ah) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.4
WHO_AM_I (0Fh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.5
RES_CONF (10h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.6
CTRL_REG1 (20h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.7
CTRL_REG2 (21h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.8
CTRL_REG3 (22h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.9
CTRL_REG4 (23h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
8.10
INTERRUPT_CFG (24h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
8.11
INT_SOURCE (25h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
8.12
STATUS_REG (27h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.13
PRESS_OUT_XL (28h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.14
PRESS_OUT_L (29h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.15
PRESS_OUT_H (2Ah) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.16
TEMP_OUT_L (2Bh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
8.17
TEMP_OUT_H (2Ch) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.18
FIFO_CTRL (2Eh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.19
FIFO_STATUS (2Fh) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
8.20
THS_P_L (30h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.21
THS_P_H (31h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.22
RPDS_L (39h) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.23
RPDS_H (3Ah) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
10
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
DocID027112 Rev 3
3/40
40
List of tables
LPS25HB
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table 15.
Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
Table 21.
Table 22.
Table 23.
Table 24.
4/40
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Pressure and temperature sensor characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
SPI slave timing values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
I2C slave timing values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Running average sample size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Serial interface pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
I2C terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
SAD+Read/Write patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Transfer when master is writing one byte to slave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Transfer when master is writing multiple bytes to slave . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Transfer when master is receiving (reading) one byte of data from slave . . . . . . . . . . . . . 20
Transfer when master is receiving (reading) multiple bytes of data from slave . . . . . . . . . 20
Registers address map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Temperature resolution configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Pressure resolution configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Output data rate bit configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Interrupt configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
FIFO mode selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Running average sample size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
HLGA-10L (2.5 x 2.5 x 0.76 mm typ.) mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
DocID027112 Rev 3
LPS25HB
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pin connections (bottom view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
SPI slave timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
I2C slave timing diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
LPS25HB electrical connections (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Read and write protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
SPI read protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Multiple byte SPI read protocol (2-byte example) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SPI write protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Multiple byte SPI write protocol (2-byte example). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
SPI read protocol in 3-wire mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Interrupt generation block and output pressure data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
HLGA-10L (2.5 x 2.5 x 0.76 mm typ.) outline and mechanical data . . . . . . . . . . . . . . . . . . 38
DocID027112 Rev 3
5/40
40
Block diagram and pin description
1
LPS25HB
Block diagram and pin description
Figure 1. Block diagram
Sensing
element
Temperature
Compensation
MUX
ADC
+ digital filter
Low noise
analog front end
p
I2C
SPI
Temperature
sensor
Voltage and
current bias
Clock and timing
Sensor bias
6/40
Vdd_IO
SCL/SPC
Figure 2. Pin connections (bottom view)
1
2
3
RES
GND
9
4
SDA/SDI/SDO
GND
8
5
SDO/SA0
7
6
CS
10
INT_DRDY
VDD
DocID027112 Rev 3
LPS25HB
Block diagram and pin description
Table 2. Pin description
Pin number
Name
Function
1
Vdd_IO
2
SCL
SPC
3
Reserved
Connect to GND
4
SDA
SDI
SDI/SDO
I²C serial data (SDA)
4-wire SPI serial data input (SDI)
3-wire serial data input /output (SDI/SDO)
5
SDO
SA0
Power supply for I/O pins
I²C serial clock (SCL)
SPI serial port clock (SPC)
4-wire SPI serial data output (SDO)
I²C less significant bit of the device address (SA0)
SPI enable
I²C/SPI mode selection
(1: SPI idle mode / I2C communication enabled;
0: SPI communication mode / I2C disabled)
6
CS
7
INT_DRDY
8
GND
0 V supply
9
GND
0 V supply
10
VDD
Power supply
Interrupt or Data Ready
DocID027112 Rev 3
7/40
40
Mechanical and electrical specifications
LPS25HB
2
Mechanical and electrical specifications
2.1
Mechanical characteristics
VDD = 1.8 V, T = 25 °C, unless otherwise noted.
Table 3. Pressure and temperature sensor characteristics
Symbol
Parameter
Test condition
Min.
Typ.(1)
Max.
Unit
-30
+105
°C
Pressure sensor characteristics
PTop
Operating temperature range
PTfull
Full accuracy temperature
range
0
+80
°C
Pop
Operating pressure range
260
1260
hPa
Pbits
Pressure output data
Psens
Pressure sensitivity
Paccrel
Relative accuracy over
pressure(2)
PaccT
Pnoise
Absolute accuracy pressure
over temperature(3)
Pressure noise(4)
24
bits
4096
LSB/
hPa
P = 800 to 1100 hPa
T = 25°C
± 0.1
hPa
P = 260 to 1260 hPa
T = 20 ∼ +60 °C
± 0.2
P = 260 to 1260 hPa
T = 0 ∼ +80 °C
±1
without embedded
filtering
0.03
with embedded
filtering
0.01
hPa
hPa
RMS
Temperature sensor characteristics
Top
Operating temperature range
Tbits
Temperature output data
16
bits
Tsens
Temperature sensitivity
480
LSB/°C
Tacc
Absolute accuracy temperature T= 0 ~ +65 °C
±2
°C
-30
105
°C
1. Typical specifications are not guaranteed.
2. Characterization data. Parameter not tested at final test.
3. Embedded quadratic compensation.
4. Pressure noise RMS evaluated in a controlled environment based on the average standard deviation of 32
measurements at highest ODR.
8/40
DocID027112 Rev 3
LPS25HB
2.2
Mechanical and electrical specifications
Electrical characteristics
VDD = 1.8 V, T = 25 °C, unless otherwise noted.
Table 4. Electrical characteristics
Symbol
VDD
Parameter
Test condition
Supply voltage
Vdd_IO IO supply voltage
@ ODR 1 Hz,
Low-resolution mode:
RES_CONF (10h) = 04h
Idd
IddPdn
Supply current
Min.
Typ.(1)
Max.
Unit
1.7
3.6
V
1.7
VDD + 0.1
V
4
µA
@ ODR 1 Hz, Low current & noise
mode with FIFO: RES_CONF (10h) =
05h, FIFO_CTRL (2Eh) = DFh,
CTRL_REG2 (21h) = 50h
4.5
µA
@ ODR 1 Hz,
High-resolution mode:
RES_CONF (10h) = 0Fh
25
µA
0.5
µA
Supply current in
power-down mode
1. Typical specifications are not guaranteed.
DocID027112 Rev 3
9/40
40
Mechanical and electrical specifications
LPS25HB
2.3
Communication interface characteristics
2.3.1
SPI - serial peripheral interface
Subject to general operating conditions for Vdd and TOP.
Table 5. SPI slave timing values
Value(1)
Symbol
Parameter
Unit
Min
tc(SPC)
SPI clock cycle
fc(SPC)
SPI clock frequency
tsu(CS)
CS setup time
6
th(CS)
CS hold time
8
tsu(SI)
SDI input setup time
5
th(SI)
SDI input hold time
15
tv(SO)
SDO valid output time
th(SO)
SDO output hold time
tdis(SO)
SDO output disable time
Max
100
ns
10
ns
50
9
50
1. Values are guaranteed at 10 MHz clock frequency for SPI with both 4 and 3 wires, based on
characterization results, not tested in production.
Figure 3. SPI slave timing diagram
Note:
10/40
Measurement points are done at 0.2·Vdd_IO and 0.8·Vdd_IO, for both ports.
DocID027112 Rev 3
MHz
LPS25HB
Mechanical and electrical specifications
I2C - inter-IC control interface
2.3.2
Subject to general operating conditions for Vdd and TOP.
Table 6. I2C slave timing values
I²C fast mode(1)
I²C standard
Symbol
Parameter (1)
f(SCL)
SCL clock frequency
Min
Max
Min
Max
Unit
0
100
0
400
kHz
tw(SCLL)
SCL clock low time
4.7
1.3
tw(SCLH)
SCL clock high time
4.0
0.6
tsu(SDA)
SDA setup time
250
100
th(SDA)
SDA data hold time
0.01
tr(SDA)
tr(SCL)
µs
ns
3.45
0
0.9
µs
SDA and SCL rise
time
1000
20
300
tf(SDA)
tf(SCL)
SDA and SCL fall
time
300
20x(VDD/5.5)
300
th(ST)
START condition hold
time
4
0.6
tsu(SR)
Repeated START
condition setup time
4.7
0.6
tsu(SP)
STOP condition setup
time
4
0.6
tw(SP:SR)
Bus free time
between STOP
and START condition
4.7
1.3
ns
µs
1. Data based on standard I2C protocol requirement, not tested in production.
Figure 4. I2C slave timing diagram
REPEATED
START
START
tsu(SR)
tw(SP:SR)
SDA
tf(SDA)
th(SDA)
tsu(SDA)
tr(SDA)
START
tsu(SP)
STOP
SCL
th(ST)
Note:
tw(SCLL)
tw(SCLH)
tr(SCL)
tf(SCL)
Measurement points are done at 0.2·Vdd_IO and 0.8·Vdd_IO, for both ports.
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Mechanical and electrical specifications
2.4
LPS25HB
Absolute maximum ratings
Stress above those listed as “Absolute maximum ratings” may cause permanent damage to
the device. This is a stress rating only and functional operation of the device under these
conditions is not implied. Exposure to maximum rating conditions for extended periods may
affect device reliability.
Table 7. Absolute maximum ratings
Symbol
VDD
Vdd_IO
Vin
P
Note:
Ratings
Maximum value
Unit
Supply voltage
-0.3 to 4.8
V
I/O pins supply voltage
-0.3 to 4.8
V
-0.3 to Vdd_IO +0.3
V
2
MPa
-40 to +125
°C
2 (HBM)
kV
Input voltage on any control pin
Overpressure
TSTG
Storage temperature range
ESD
Electrostatic discharge protection
Supply voltage on any pin should never exceed 4.8 V.
This device is sensitive to mechanical shock, improper handling can cause
permanent damage to the part.
This device is sensitive to electrostatic discharge (ESD), improper handling can
cause permanent damage to the part.
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3
Functionality
Functionality
The LPS25HB is a high resolution, digital output pressure sensor packaged in an HLGA fullmold package. The complete device includes a sensing element based on a piezoresistive
Wheatstone bridge approach, and an IC interface which communicates a digital signal from
the sensing element to the application.
3.1
Sensing element
An ST proprietary process is used to obtain a silicon membrane for MEMS pressure
sensors. When pressure is applied, the membrane deflection induces an imbalance in the
Wheatstone bridge piezoresistances whose output signal is converted by the IC interface.
3.2
I2C interface
The complete measurement chain is composed of a low-noise amplifier which converts the
resistance unbalance of the MEMS sensors (pressure and temperature) into an analog
voltage using an analog-to-digital converter.
The pressure and temperature data may be accessed through an I²C/SPI interface thus
making the device particularly suitable for direct interfacing with a microcontroller.
The LPS25HB features a Data-Ready signal which indicates when a new set of measured
pressure and temperature data are available, thus simplifying data synchronization in the
digital system that uses the device.
3.3
Factory calibration
The IC interface is factory calibrated at three temperatures and two pressures for sensitivity
and accuracy.
The trimming values are stored inside the device in a non-volatile structure. When the
device is turned on, the trimming parameters are downloaded into the registers to be
employed during normal operation which allows the device to be used without requiring any
further calibration.
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FIFO
4
LPS25HB
FIFO
The LPS25HB embeds 32-slot data FIFO to store the pressure output values. The FIFO
allows consistent power saving for the system, since the host processor does not need to
continuously poll data from the sensor, but it can wake up only when needed and burst the
significant data out from the FIFO.
This buffer can work according to seven different modes: Bypass mode, FIFO mode, Stream
mode, Stream-to-FIFO mode, Bypass-to-Stream mode, Bypass-to-FIFO mode and FIFO
Mean mode.
The FIFO buffer is enabled when the FIFO_EN bit in CTRL_REG2 (21h) is set to '1' and
each mode is selected by the F_MODE[2:0] bits in FIFO_CTRL (2Eh).
FIFO threshold status, FIFO overrun events and the number of unread samples stored are
available in the FIFO_STATUS (2Fh) register and can be set to generate dedicated
interrupts on the INT_DRDY pin in the CTRL_REG4 (23h) register.
4.1
Bypass mode
In Bypass mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '000'), the FIFO is not
operational and it remains empty.
4.2
FIFO mode
In FIFO mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '001'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h) are stored in
the FIFO.
A watermark interrupt can be enabled (STOP_ON_FTH bit set to '1' in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
bits of FIFO_CTRL (2Eh). The FIFO continues filling until it is full (32 slots of data for
pressure output). When full, the FIFO stops collecting data.
4.3
Stream mode
In Stream mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '010'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h) are stored in
the FIFO. The FIFO continues filling until it's full (32 slots of data for pressure output). When
full, the FIFO discards the older data as the new arrive. A watermark interrupt can be
enabled and set as in FIFO mode.
4.4
Stream-to-FIFO mode
In Stream-to-FIFO mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '011'), the data from
PRESS_OUT_H (2Ah), PRESS_OUT_L (29h) PRESS_OUT_L (29h) and PRESS_OUT_XL
(28h) are stored in the FIFO.
A Watermark interrupt can be enabled (STOP_ON_FTH bit set to '1' in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
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LPS25HB
FIFO
bits of FIFO_CTRL (2Eh).The FIFO continues filling until it's full (32 slots of data for
pressure output). When full, the FIFO discards the older data as the new arrive. Once a
trigger event occurs, the FIFO starts operating in FIFO mode. A trigger event can be
configured in INTERRUPT_CFG (24h).
4.5
Bypass-to-Stream mode
In Bypass-to-Stream mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '100'), the FIFO is in
Bypass mode until a trigger event occurs and the FIFO starts operating in Stream mode. A
trigger event can be configured in INTERRUPT_CFG (24h).
4.6
FIFO Mean mode
In FIFO Mean mode (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '110'), the pressure data are
not directly sent to the output register but are first stored in the FIFO to calculate the
average. In this mode the FIFO is used to implement a moving average of the pressure data
with a 2, 4, 8, 16 or 32 sample set by changing the watermark defined by the
WTM_POINT[4:0] bits of FIFO_CTRL (2Eh) (refer to Table 8).
Table 8. Running average sample size
WTM_POINT[4:0]
FIFO Mean mode sample size
00001
2-sample moving average
00011
4-sample moving average
00111
8-sample moving average
01111
16-sample moving average
11111
32-sample moving average
There are two possible ways of providing the output pressure data averaged by FIFO:
1.
If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to '0', the output is at the same
ODR of the data coming from the sensor;
2.
If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to '1', the output is decimated
(@1 Hz when ODR = 4 or 2; @1.04 Hz when ODR=3).
Please note that when using the FIFO Mean mode it is not possible to access the FIFO
content.
4.7
Bypass-to-FIFO mode
In Bypass-to-FIFO (F_MODE[2:0] in FIFO_CTRL (2Eh) set to '111'), the FIFO is in Bypass
mode until a trigger event occurs and the FIFO starts operating in FIFO mode. A trigger
event can be configured in INTERRUPT_CFG (24h).
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FIFO
4.8
LPS25HB
Retrieving data from FIFO
When the FIFO is enabled, FIFO data are read from PRESS_OUT_H (2Ah),
PRESS_OUT_L (29h), and PRESS_OUT_XL (28h) registers.
Each time data is read from the FIFO, the oldest data are placed in the PRESS_OUT_H
(2Ah), PRESS_OUT_L (29h) and PRESS_OUT_XL (28h) registers and both single-read
and read-burst operations can be used.
The reading address is automatically updated by the device and it rolls back to 28h when
register 2Ah is reached. In order to read all FIFO levels in a multiple byte reading, 96 bytes
(3 output registers by 32 levels) must be read.
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5
Application hints
Application hints
Figure 5. LPS25HB electrical connections (top view)
GND
VDD
GND
C1
Pin indicator
10
1
7
INT_DRDY
2
6
CS
3
4
5
GND
SDO/SA0
SCL/SPC
8
SDA/SDI/SDO
Vdd_IO
9
The device power supply must be provided through the VDD line; the power supply
decoupling capacitor C1 (100 nF) must be placed as near as possible to the supply pads of
the device. Depending on the application, an additional capacitor of 4.7 µF could be placed
on VDD line.
The functionality of the device and the measured data outputs are selectable and accessible
through the I²C/SPI interface. When using the I²C, CS must be tied to Vdd_IO.
All the voltage and ground supplies must be present at the same time to have proper
behavior of the IC (refer to Figure 5.). It is possible to remove VDD while maintaining
Vdd_IO without blocking the communication bus, in this condition the measurement chain is
powered off.
5.1
Soldering information
The HLGA package is compliant with the ECOPACK® standard and it is qualified for
soldering heat resistance according to JEDEC J-STD-020.
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Digital interfaces
LPS25HB
6
Digital interfaces
6.1
I2C serial interface
The registers embedded in the LPS25HB may be accessed through both the I²C and SPI
serial interfaces. The latter may be SW configured to operate either in 3-wire or 4-wire
interface mode.
The serial interfaces are mapped onto the same pads. To select/exploit the I²C interface, the
CS line must be tied high (i.e. connected to Vdd_IO); to select the SPI interface, the CS line
must be tied low (i.e. connected to GND).
Table 9. Serial interface pin description
Pin name
SPI enable
I²C/SPI mode selection (1: I²C mode; 0: SPI enabled
CS
SCL/SPC
I²C serial clock (SCL)
SPI serial port clock (SPC)
SDA
SDI
SDI/SDO
I²C serial data (SDA)
4-wire SPI serial data input (SDI)
3-wire serial data input /output (SDI/SDO)
SDO
SAO
6.2
Pin
SPI serial data output (SDO)
I²C less significant bit of the device address (SA0)
I2C serial interface (CS = High)
The LPS25HB I²C is a bus slave. The I²C is employed to write data into registers whose
content can also be read back.
The relevant I²C terminology is given in Table 9.
Table 10. I2C terminology
Term
Description
Transmitter The device which sends data to the bus
Receiver
The device which receives data from the bus
Master
The device which initiates a transfer, generates clock signals and terminates a transfer
Slave
The device addressed by the master
There are two signals associated with the I²C bus: the serial clock line (SCL) and the serial
data line (SDA). The latter is a bi-directional line used for sending and receiving the data
to/from the interface. Both lines have to be connected to Vdd_IO through pull-up resistors.
The I²C interface is compliant with fast mode (400 kHz) I²C standards as well as with the
normal mode.
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6.2.1
Digital interfaces
I2C operation
The transaction on the bus is started through a START (ST) signal. A start condition is
defined as a HIGH-to-LOW transition on the data line while the SCL line is held HIGH. After
this has been transmitted by the master, the bus is considered busy. The next data byte
transmitted after the start condition contains the address of the slave in the first 7 bits and
the eighth bit tells whether the master is receiving data from the slave or transmitting data to
the slave. When an address is sent, each device in the system compares the first seven bits
after a start condition with its address. If they match, the device considers itself addressed by
the master.
The slave address (SAD) associated to the LPS25HB is 101110xb. The SDO/SA0 pad can
be used to modify the less significant bit of the device address. If the SA0 pad is connected
to the voltage supply, LSb is ‘1’ (address 1011101b), otherwise if the SA0 pad is connected to
ground, the LSb value is ‘0’ (address 1011100b). This solution permits to connect and
address two different LPS25HB devices to the same I²C lines.
Data transfer with acknowledge is mandatory. The transmitter must release the SDA line
during the acknowledge pulse. The receiver must then pull the data line LOW so that it
remains stable low during the HIGH period of the acknowledge clock pulse. A receiver which
has been addressed is obliged to generate an acknowledge after each byte of data received.
The I²C embedded in the LPS25HB behaves like a slave device and the following protocol
must be adhered to. After the start condition (ST) a slave address is sent, once a slave
acknowledge (SAK) has been returned, an 8-bit sub-address (SUB) will be transmitted: the 7
LSB represents the actual register address while the MSB enables address auto increment.
If the MSb of the SUB field is ‘1’, the SUB (register address) will be automatically increased
to allow multiple data read/write.
The slave address is completed with a Read/Write bit. If the bit is ‘1’ (Read), a repeated
START (SR) condition must be issued after the two sub-address bytes; if the bit is ‘0’ (Write)
the master will transmit to the slave with direction unchanged. Table 11 explains how the
SAD+read/write bit pattern is composed, listing all the possible configurations.
Table 11. SAD+Read/Write patterns
Command
SAD[6:1]
SAD[0] = SA0
R/W
SAD+R/W
Read
101110
0
1
10111001 (B9h)
Write
101110
0
0
10111000 (B8h)
Read
101110
1
1
10111011 (BBh)
Write
101110
1
0
10111010 (BAh)
Table 12. Transfer when master is writing one byte to slave
Master
Slave
ST
SAD + W
SUB
SAK
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SAK
SP
SAK
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Digital interfaces
LPS25HB
Table 13. Transfer when master is writing multiple bytes to slave
Master
ST
SAD + W
SUB
Slave
SAK
DATA
DATA
SAK
SAK
SP
SAK
Table 14. Transfer when master is receiving (reading) one byte of data from slave
Master
ST
SAD + W
Slave
SUB
SAK
SR
SAD + R
SAK
NMAK
SAK
SP
DATA
Table 15. Transfer when master is receiving (reading) multiple bytes of data from slave
Master
Slave
ST SAD+W
SUB
SAK
SR SAD+R
SAK
MAK
SAK
DATA
MAK
DATA
NMAK SP
DATA
Data are transmitted in byte format (DATA). Each data transfer contains 8 bits. The number
of bytes transferred per transfer is unlimited. Data is transferred with the most significant bit
(MSb) first. If a receiver can’t receive another complete byte of data until it has performed
some other functions, it can hold the clock line, SCL LOW to force the transmitter into a wait
state. Data transfer only continues when the receiver is ready for another byte and releases
the data line. If a slave receiver does not acknowledge the slave address (i.e. it is not able to
receive because it is performing some real-time function) the data line must be kept HIGH by
the slave. The master can then abort the transfer. A LOW-to-HIGH transition on the SDA line
while the SCL line is HIGH is defined as a STOP condition. Each data transfer must be
terminated by the generation of a STOP (SP) condition.
In order to read multiple bytes incrementing the register address, it is necessary to assert
the most significant bit of the sub-address field. In other words, SUB(7) must be equal to 1
while SUB(6-0) represents the address of the first register to be read.
In the presented communication format MAK is Master acknowledge and NMAK is no
master acknowledge.
6.3
SPI bus interface
The LPS25HB SPI is a bus slave. The SPI allows writing to and reading from the registers of
the device.
The serial interface interacts with the outside world with 4 wires: CS, SPC, SDI and SDO.
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Digital interfaces
Figure 6. Read and write protocol
CS
SPC
SDI
DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
RW
MS AD5 AD4 AD3 AD2 AD1 AD0
SDO
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
CS is the serial port enable and it is controlled by the SPI master. It goes low at the start of
the transmission and returns to high at the end. SPC is the serial port clock and it is
controlled by the SPI master. It is stopped high when CS is high (no transmission). SDI and
SDO are respectively the serial port data input and output. Those lines are driven at the
falling edge of SPC and should be captured at the rising edge of SPC.
Both the read register and write register commands are completed in 16 clock pulses or in
multiples of 8 in the case of multiple read/write bytes. Bit duration is the time between two
falling edges of SPC. The first bit (bit 0) starts at the first falling edge of SPC after the falling
edge of CS while the last bit (bit 15, bit 23,...) starts at the last falling edge of SPC just before
the rising edge of CS.
bit 0: RW bit. When 0, the data DI(7:0) is written into the device. When 1, the data DO(7:0)
from the device is read. In the latter case, the chip will drive SDO at the start of bit 8.
bit 1: MS bit. When 0, the address will remain unchanged in multiple read/write commands.
When 1, the address will be auto incremented in multiple read/write commands.
bit 2-7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DI(7:0) (write mode). This is the data that is written into the device (MSb first).
bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).
In multiple read/write commands further blocks of 8 clock periods are added. When the MS
bit is 0 the address used to read/write data remains the same for every block. When the MS
bit is 1 the address used to read/write data is increased at every block.
The function and the behavior of SDI and SDO remain unchanged.
6.3.1
SPI read
Figure 7. SPI read protocol
CS
SPC
SDI
RW
MS AD5 AD4 AD3 AD2 AD1 AD0
SDO
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
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Digital interfaces
LPS25HB
The SPI read command is performed with 16 clock pulses. The multiple byte read command
is performed by adding blocks of 8 clock pulses to the previous one.
bit 0: READ bit. The value is 1.
bit 1: MS bit. When 0, does not increment the address; when 1, increments the address in
multiple reads.
bit 2-7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).
bit 16-...: data DO(...-8). Further data in multiple byte reads.
Figure 8. Multiple byte SPI read protocol (2-byte example)
CS
SPC
SDI
SDO
6.3.2
SPI write
Figure 9. SPI write protocol
CS
SPC
SDI
DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
RW
AD6 AD5 AD4 AD3 AD2 AD1 AD0
The SPI write command is performed with 16 clock pulses. The multiple byte write command
is performed by adding blocks of 8 clock pulses to the previous one.
bit 0: WRITE bit. The value is 0.
bit 1: MS bit. When 0, does not increment the address; when 1, increments the address in
multiple writes.
bit 2 -7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DI(7:0) (write mode). This is the data that is written in the device (MSb first).
bit 16-...: data DI(...-8). Further data in multiple byte writes.
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Digital interfaces
Figure 10. Multiple byte SPI write protocol (2-byte example)
CS
SPC
SDI
DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0 DI15 DI14 DI13 DI12 DI11 DI10 DI9 DI8
RW
MS AD5 AD4 AD3 AD2 AD1 AD0
6.3.3
SPI read in 3-wire mode
A 3-wire mode is entered by setting to ‘1’ bit SIM (SPI serial interface mode selection) in
CTRL_REG1.
Figure 11. SPI read protocol in 3-wire mode
CS
SPC
SDI/O
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
RW
MS AD5 AD4 AD3 AD2 AD1 AD0
The SPI read command is performed with 16 clock pulses:
bit 0: READ bit. The value is 1.
bit 1: MS bit. When 0, does not increment the address; when 1, increments the address in
multiple reads.
bit 2-7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).
A multiple read command is also available in 3-wire mode.
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Register mapping
7
LPS25HB
Register mapping
Table 16 provides a quick overview of the 8-bit registers embedded in the device.
Table 16. Registers address map
Register
Name
Type
Reserved
Default
Hex
Binary
00-07
0D - 0E
-
REF_P_XL
R/W
08
00000000
REF_P_L
R/W
09
00000000
REF_P_H
R/W
0A
00000000
WHO_AM_I
R
0F
10111101
RES_CONF
R/W
10
00000101
11-1F
-
Reserved
CTRL_REG1
R/W
20
00000000
CTRL_REG2
R/W
21
00000000
CTRL_REG3
R/W
22
00000000
CTRL_REG4
R/W
23
00000000
INTERRUPT_CFG
R/W
24
00000000
INT_SOURCE
R
25
00000000
26
-
Reserved
STATUS_REG
R
27
00000000
PRESS_OUT_XL
R
28
output
PRESS_OUT_L
R
29
output
PRESS_OUT_H
R
2A
output
TEMP_OUT_L
R
2B
output
TEMP_OUT_H
R
2C
output
2D
-
Reserved
FIFO_CTRL
R/W
2E
00000000
FIFO_STATUS
R
2F
00100000
THS_P_L
R/W
30
00000000
THS_P_H
R/W
31
00000000
32-38
-
Reserved
24/40
Address
RPDS_L
R/W
39
00000000
RPDS_H
R/W
3A
00000000
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Function and
comment
Reserved
Who am I register
Reserved
Reserved
Reserved
LPS25HB
Register mapping
Registers marked as Reserved must not be changed. Writing to those registers may cause
permanent damage to the device.
To guarantee the proper behavior of the device, all register addresses not listed in the
previous table must not be accessed and the content stored in those registers must not be
changed.
The content of the registers that are loaded at boot should not be changed. They contain the
factory calibration values. Their content is automatically restored when the device is
powered up.
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Register description
8
LPS25HB
Register description
The device contains a set of registers which are used to control its behavior and to retrieve
pressure and temperature data. The register address, made up of 7 bits, is used to identify
them and to read/write the data through the serial interface.
8.1
REF_P_XL (08h)
Reference pressure (LSB data)
7
6
5
4
3
2
1
0
REFL7
REFL6
REFL5
REFL4
REFL3
REFL2
REFL1
REFL0
REFL[7:0]
This register contains the low part of the reference pressure value.
The Reference pressure value is a 24-bit data subtracted from the sensor output
measurement and it is composed of REF_P_H (0Ah), REF_P_L (09h) and REF_P_XL
(08h). The value is expressed as 2’s complement.
The reference pressure value is subtracted from the sensor output measurement, to detect
a measured pressure beyond programmed limits (refer to INTERRUPT_CFG (24h)
register), and is used for the Autozero function.
8.2
REF_P_L (09h)
Reference pressure (middle part)
15
14
13
12
11
10
9
8
REFL15
REFL14
REFL13
REFL12
REFL11
REFL10
REFL9
REFL8
REFL[15:8]
8.3
This register contains the mid part of the reference pressure value.
Refer to REF_P_XL (08h).
REF_P_H (0Ah)
Reference pressure (MSB data)
23
22
21
20
19
18
17
16
REFL23
REFL22
REFL21
REFL20
REFL19
REFL18
REFL17
REFL16
REFL[23:16]
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This register contains the high part of the reference pressure value.
Refer to REF_P_XL (08h).
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LPS25HB
8.4
Register description
WHO_AM_I (0Fh)
Device who am I
8.5
7
6
5
4
3
2
1
0
1
0
1
1
1
1
0
1
4
3
2
1
0
AVGT1
AVGT0
AVGP1
AVGP0
RES_CONF (10h)
Pressure and temperature resolution
7
6
5
Reserved
AVGT[1:0]
Temperature internal average configuration. Default 11
Refer to Table 17 for all the configurations
AVGP[1:0]
Pressure internal average configuration. Default 11
Refer to Table 18 for all the configurations
Table 17. Temperature resolution configuration
AVGT1
AVGT0
Nr. internal average
0
0
8
0
1
16
1
0
32
1
1
64
Table 18. Pressure resolution configuration
AVGP1
AVGP0
Nr. internal average
0
0
8
0
1
32
1
0
128
1
1
512
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Register description
8.6
LPS25HB
CTRL_REG1 (20h)
Control register 1
7
6
5
4
3
2
1
0
PD
ODR2
ODR1
ODR0
DIFF_EN
BDU
RESET_AZ
SIM
PD
Power-down control. Default value: 0
(0: power-down mode; 1: active mode)
ODR [2:0]
Output data rate selection. Default value: 000
Refer to Table 19.
DIFF_EN
Interrupt generation enable. Default value: 0
(0: interrupt generation disabled; 1: interrupt generation enabled)
BDU
Block data update. Default value: 0
(0: continuous update;
1: output registers not updated until MSB and LSB have been read)
RESET_AZ
Reset Autozero function. Default value: 0.
(0: normal mode; 1: reset Autozero function)
SIM
SPI Serial Interface Mode selection.Default value: 0
(0: 4-wire interface; 1: 3-wire interface)
The PD bit allows the turn on of the device. The device is in power-down mode when PD is
set to ‘0’ (default value after boot). The device is active when PD is set to ‘1’.
The ODR[2,0] bits can be configured as described in Table 19. When ODR[2,0] are set to
‘000’ the device enables one-shot mode. When ‘ONESHOT’ bit in CTRL_REG2 (21h) is
set to ‘1’, a new set of data for pressure and temperature is acquired.
Table 19. Output data rate bit configurations
ODR2
ODR1
ODR0
Pressure (Hz)
Temperature (Hz)
0
0
0
0
0
1
1 Hz
1 Hz
0
1
0
7 Hz
7 Hz
0
1
1
12.5 Hz
12.5 Hz
1
0
0
25 Hz
25 Hz
1
0
1
One-shot mode enabled
Reserved
The DIFF_EN bit is used to enable the computing of differential pressure output. It is
recommended to enable DIFF_EN after the configuration of REF_P_H (0Ah), REF_P_L
(09h), REF_P_XL (08h), THS_P_H (31h) and THS_P_L (30h).
The BDU bit is used to inhibit the update of the output registers between the reading of the
upper and lower register parts. In default mode (BDU = ‘0’), the lower and upper register
parts are updated continuously. When the BDU is activated (BDU = ‘1’), the content of the
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LPS25HB
Register description
output registers is not updated until both MSB and LSB are read, avoiding the reading of
values related to different samples.
The RESET_AZ bit is used to reset the AutoZero function. Resetting REF_P_H (0Ah),
REF_P_L (09h) and REF_P_XL (08h) sets the pressure reference registers RPDS_H (3Ah)
and RPDS_L (39h) to the default value. RESET_AZ is self-cleared. For the AutoZero
function please refer to CTRL_REG2 (21h).
The SIM bit selects the SPI serial interface mode:
8.7
•
0: (default value) 4-wire SPI interface mode selected;
•
1: 3-wire SPI interface mode selected.
CTRL_REG2 (21h)
Control register 2
7
6
5
4
3
2
1
0
BOOT
FIFO_EN
STOP_ON_FTH
FIFO_MEAN_DEC
I2C_EN
SWRESET
AUTO_ZERO
ONE_SHOT
BOOT
Reboot memory content. Default value: 0.
(0: normal mode; 1: reboot memory content). The bit is self-cleared when the
BOOT is completed.
FIFO_EN
FIFO enable. Default value: 0.
(0: disable; 1: enable)
STOP_ON_FTH
Stop on FIFO threshold. Enable FIFO watermark level use. Default value: 0
(0: disable; 1: enable).
FIFO_MEAN_DEC
Enable to decimate the output pressure to 1Hz with FIFO Mean mode.
Default value: 0
(0: disable / 1: enable)
I2C_EN
I2C interface enabled. Default value 0.
(0: I2C enabled;1: I2C disabled)
SWRESET
Software reset. Default value: 0.
(0: normal mode; 1: software reset).
The bit is self-cleared when the reset is completed.
AUTOZERO
Autozero enable. Default value: 0.
(0: normal mode; 1: Autozero enabled)
ONE_SHOT
One shot mode enable. Default value: 0.
(0: idle mode; 1: a new dataset is acquired)
The BOOT bit is used to refresh the content of the internal registers stored in the Flash
memory block. At device power-up the content of the Flash memory block is transferred to
the internal registers related to the trimming functions to allow correct behavior of the device
itself. If for any reason the content of the trimming registers is modified, it is sufficient to use
this bit to restore the correct values. When the BOOT bit is set to ‘1’, the content of the
internal Flash is copied inside the corresponding internal registers and is used to calibrate
the device. These values are factory trimmed and they are different for every device. They
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Register description
LPS25HB
allow correct behavior of the device and normally they should not be changed. At the end of
the boot process, the BOOT bit is set again to ‘0’ by hardware. The BOOT bit will be effected
as soon as it is set.
FIFO_MEAN_DEC bit is to decimate the output pressure to 1Hz with FIFO Mean mode.
When this bit is "1", the averaged pressure data by FIFO Mean mode would be updated @
1Hz. Otherwise, Averaged pressure data will be updated according to ODR defined.
SWRESET is the software reset bit. The device is reset to the power-on configuration after
SWRESET bit is set to '1'. To complete the reset of device, BOOT bit is also need to be set
to '1' after SWRESET bit is set to '1'.
AUTOZERO, when set to ‘1’, the actual pressure output value is copied in REF_P_H (0Ah),
REF_P_L (09h) and REF_P_XL (08h). When this bit is enabled, the register content of
REF_P is subtracted from the pressure output value.
The ONE_SHOT bit is used to start a new conversion when the ODR[2,0] bits in
CTRL_REG1 (20h) are set to ‘000’. Writing a ‘1’ in ONE_SHOT triggers a single
measurement of pressure and temperature. Once the measurement is done, the
ONE_SHOT bit will self-clear, the new data are available in the output registers, and the
STATUS_REG bits are updated.
8.8
CTRL_REG3 (22h)
Interrupt control
7
6
INT_H_L
PP_OD
5
4
3
2
Reserved
1
0
INT_S2
INT_S1
INT_H_L
Interrupt active high, low. Default value: 0.
(0: active high; 1: active low)
PP_OD
Push-pull/open drain selection on interrupt pads. Default value: 0.
(0: push-pull; 1: open drain)
INT_S[2:1]
Data signal on INT_DRDY pin control bits. Default value: 00.
Refer to Table 20.
Table 20. Interrupt configurations
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INT_S2
INT_S1
INT_DRDY pin configuration
0
0
Data signal (see CTRL_REG4 (23h))
0
1
Pressure high (P_high)
1
0
Pressure low (P_low)
1
1
Pressure low OR high
DocID027112 Rev 3
LPS25HB
Register description
The device features one set of programmable interrupt sources (INT) that can be configured
to trigger different pressure events. Figure 12 shows the block diagram of the interrupt
generation block and output pressure data.
The device may also be configured to generate, through the INT_DRDY pin, a Data Ready
signal (DRDY) which indicates when a new measured pressure data is available, thus
simplifying data synchronization in digital systems or optimizing system power consumption.
Figure 12. Interrupt generation block and output pressure data
8.9
CTRL_REG4 (23h)
Interrupt configuration
7
6
5
4
3
2
1
0
0
0
0
0
F_EMPTY
F_FTH
F_OVR
DRDY
F_EMPTY
FIFO empty flag on INT_DRDY pin. Default value: 0.
(0: disable; 1: enable)
F_FTH
FIFO threshold (watermark) status on INT_DRDY pin to indicate that FIFO is filled
up to the threshold level. Default value: 0.
(0: disable; 1: enable)
F_OVR
FIFO overrun interrupt on INT_DRDY pin to indicate that FIFO is full in FIFO mode
or that an overrun occurred in Stream mode. Default value: 0.
(0: disable; 1: enable)
DRDY
Data-ready signal on INT_DRDY pin. Default value: 0.
(0: disable; 1: enable)
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40
Register description
8.10
LPS25HB
INTERRUPT_CFG (24h)
Interrupt configuration
7
6
5
4
3
Reserved
8.11
2
1
0
LIR
PL_E
PH_E
LIR
Latch interrupt request to the INT_SOURCE (25h) register. Default value: 0.
(0: interrupt request not latched; 1: interrupt request latched)
PL_E
Enable interrupt generation on differential pressure low event. Default value: 0.
(0: disable interrupt request; 1: enable interrupt request on measured differential
pressure value lower than preset threshold)
PH_E
Enable interrupt generation on differential pressure high event. Default value: 0.
(0: disable interrupt request; 1: enable interrupt request on measured differential
pressure value higher than preset threshold)
INT_SOURCE (25h)
Interrupt source
7
6
5
4
3
2
1
0
0
0
0
0
0
IA
PL
PH
IA
Interrupt active.
(0: no interrupt has been generated;
1: one or more interrupt events have been generated).
PL
Differential pressure Low.
(0: no interrupt has been generated;
1: Low differential pressure event has occurred).
PH
Differential pressure High.
(0: no interrupt has been generated;
1: High differential pressure event has occurred).
INT_SOURCE register is cleared by reading it.
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LPS25HB
8.12
Register description
STATUS_REG (27h)
Status register
7
6
RES
5
4
P_OR
T_OR
3
2
RES
1
0
P_DA
T_DA
P_OR
Pressure data overrun.
(0: no overrun has occurred;
1: new data for pressure has overwritten the previous one)
T_OR
Temperature data overrun.
(0: no overrun has occurred;
1: a new data for temperature has overwritten the previous one)
P_DA
Pressure data available.
(0: new data for pressure is not yet available;
1: new data for pressure is available)
T_DA
Temperature data available.
(0: new data for temperature is not yet available;
1: new data for temperature is available)
This register is updated every ODR cycle, regardless of the BDU value in CTRL_REG1
(20h).
P_OR bit is set to '1' whenever new pressure data is available and P_DA was set in the
previous ODR cycle and not cleared. P_OR is cleared when the PRESS_OUT_H (2Ah)
register is read.
T_OR is set to ‘1’ whenever new temperature data is available and T_DA was set in the
previous ODR cycle and not cleared. T_OR is cleared when the TEMP_OUT_H (2Ch)
register is read.
P_DA is set to 1 whenever a new pressure sample is available. P_DA is cleared when the
PRESS_OUT_H (2Ah) register is read.
T_DA is set to 1 whenever a new temperature sample is available. T_DA is cleared when
the TEMP_OUT_H (2Ch) register is read.
8.13
PRESS_OUT_XL (28h)
Pressure output value (LSB)
7
6
5
4
3
2
1
0
POUT7
POUT6
POUT5
POUT4
POUT3
POUT2
POUT1
POUT0
POUT[7:0]
This register contains the low part of the pressure output value.
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40
Register description
LPS25HB
The pressure output value is a 24-bit data that contains the measured pressure. It is
composed of PRESS_OUT_H (2Ah), PRESS_OUT_L (29h) and PRESS_OUT_XL (28h).
The value is expressed as 2’s complement.
8.14
PRESS_OUT_L (29h)
Pressure output value (mid part)
15
14
13
12
11
10
9
8
POUT15
POUT14
POUT13
POUT12
POUT11
POUT10
POUT9
POUT8
POUT[15:8]
8.15
This register contains the mid part of the pressure output value. Refer to
PRESS_OUT_XL (28h).
PRESS_OUT_H (2Ah)
Pressure output value (MSB)
23
22
21
20
19
18
17
16
POUT23
POUT22
POUT21
POUT20
POUT19
POUT18
POUT17
POUT16
POUT[23:16]
8.16
This register contains the high part of the pressure output value. Refer to
PRESS_OUT_XL (28h).
TEMP_OUT_L (2Bh)
Temperature output value (LSB)
7
6
5
4
3
2
1
0
TOUT7
TOUT6
TOUT5
TOUT4
TOUT3
TOUT2
TOUT1
TOUT0
TOUT[7:0]
This register contains the low part of the temperature output value.
The temperature output value is a 16-bit data that contains the measured temperature. It is
composed of TEMP_OUT_H (2Ch) and TEMP_OUT_L (2Bh). The value is expressed as 2’s
complement.
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LPS25HB
8.17
Register description
TEMP_OUT_H (2Ch)
Temperature output value (MSB)
15
14
13
12
11
10
9
8
TOUT15
TOUT14
TOUT13
TOUT12
TOUT11
TOUT10
TOUT9
TOUT8
TOUT[15:8]
This register contains the high part of the temperature output value.
The temperature output value is a 16-bit data that contains the measured temperature. It is
composed by TEMP_OUT_H (2Ch) and TEMP_OUT_L (2Bh). The value is expressed as
2’s complement.
8.18
FIFO_CTRL (2Eh)
FIFO control
7
6
5
4
F_MODE2
F_MODE1
F_MODE0
3
2
1
0
WTM_POINT4 WTM_POINT3 WTM_POINT2 WTM_POINT1 WTM_POINT0
F_MODE[2:0]
FIFO mode selection. Default value: 000.
Refer to Table 21 and Section 4 for additional details.
WTM_POINT[4:0]
FIFO threshold (watermark) level selection.
Refer to Table 22 for additional details.
Table 21. FIFO mode selection
F_MOD F_MODE F_MODE
FIFO mode
0
0
0
Bypass mode
0
0
1
FIFO mode
0
1
0
Stream mode
0
1
1
Stream-to-FIFO mode
1
0
0
Bypass-to-Stream mode
1
0
1
Not available
1
1
0
FIFO Mean mode
1
1
1
Bypass-to-FIFO mode
FIFO Mean mode: The FIFO can be used for implementing a HW moving average on the
pressure measurements. The number of samples of the moving average can be 2, 4, 8, 16
or 32 samples by selecting the watermark levels as per Table 22. Different configurations are
not allowed.
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40
Register description
LPS25HB
Table 22. Running average sample size
WTM_POINT[4:0]
FIFO Mean mode sample size
00001
2-sample moving average
00011
4-sample moving average
00111
8-sample moving average
01111
16-sample moving average
11111
32-sample moving average
Please note that when using the FIFO Mean mode it is not possible to access the FIFO
content.
8.19
FIFO_STATUS (2Fh)
FIFO status
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7
6
5
4
3
2
1
0
FTH_FIFO
OVR
EMPTY_FIFO
FSS4
FSS3
FSS2
FSS1
FSS0
FTH_FIFO
FIFO threshold status.
(0: FIFO filling is lower than FTH level;
1: FIFO filling is equal or higher than FTH level).
OVR
Overrun bit status.
(0: FIFO not full;
1: FIFO is full and at least one sample in the FIFO has been overwritten).
EMPTY_FIFO
Empty FIFO bit status.
(0: FIFO not empty; 1: FIFO is empty).
FSS[4:0]
FIFO stored data level.
(00000: FIFO empty @ EMPTY_FIFO "1" or 1st sample stored in
[email protected]_FIFO "0"; 11111: FIFO is full and has 32 unread samples).
DocID027112 Rev 3
LPS25HB
8.20
Register description
THS_P_L (30h)
Least significant bits of the threshold value for pressure interrupt generation.
7
6
5
4
3
2
1
0
THS7
THS6
THS5
THS4
THS3
THS2
THS1
THS0
THS[7:0]
This register contains the low part of threshold value for pressure interrupt generation.
The threshold value for pressure interrupt generation is a 16-bit register composed of
THS_P_H (31h) and THS_P_L (30h). The value is expressed as unsigned number: Interrupt
threshold(hPA) = (THS_P)/16.
8.21
THS_P_H (31h)
Most significant bits of the threshold value for pressure interrupt generation.
15
14
13
12
11
10
9
8
THS15
THS14
THS13
THS12
THS11
THS10
THS9
THS8
THS[15:8]
8.22
This register contains the high part of threshold value for pressure interrupt generation.
Refer to THS_P_L (30h).
RPDS_L (39h)
Pressure offset (LSB data)
7
6
5
4
3
2
1
0
RPDS7
RPDS6
RSPDS5
RPDS4
RPDS3
RPDS2
RPDS1
RPDS0
RPDS[7:0]
This register contains the low part of the pressure offset value.
The pressure offset value is a 16-bit data that can be used to implement One-Point
Calibration (OPC) after soldering, This value is composed of RPDS_H (3Ah) and RPDS_L
(39h). The value is expressed as 2’s complement.
8.23
RPDS_H (3Ah)
Pressure offset (MSB data)
7
6
5
4
3
2
1
0
RPDS15
RPDS14
RSPDS13
RPDS12
RPDS11
RPDS2
RPDS9
RPDS8
RPDS[15:8]
This register contains the high part of the pressure offset value.
Refer to RPDS_L (39h).
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40
Package mechanical data
9
LPS25HB
Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
Figure 13. HLGA-10L (2.5 x 2.5 x 0.76 mm typ.) outline and mechanical data
1. Dimensions are in millimeter unless otherwise specified General tolerance is +/-0.1mm unless otherwise
specified
Table 23. HLGA-10L (2.5 x 2.5 x 0.76 mm typ.) mechanical data
38/40
Item
Dimension (mm)
Tolerance (mm)
Length [L]
2.5
± 0.1
Width [W]
2.5
± 0.1
Height [H]
0.8 MAX
/
Pad size
0.3 x 0.45
±0.05
DocID027112 Rev 3
LPS25HB
10
Revision history
Revision history
Table 24. Document revision history
Date
Revision
30-Oct-2014
1
Initial release
2
Updated Table 1: Device summary.
Minor update in Figure 2: Pin connections (bottom view),
Figure 5: LPS25HB electrical connections (top view),
Section 4: FIFO, Section 8.1: REF_P_XL (08h),
Section 8.15: PRESS_OUT_H (2Ah) and Figure 12:
Interrupt generation block and output pressure data.
21-May-2015
14-Jun-2016
3
Changes
Updated:
- Features
- Table 4: Electrical characteristics;
- Table 6: I2C slave timing values;
- Table 4: Electrical characteristics,
- Table 16: Registers address map
- Section 9: Package mechanical data
Updated registers’ information:
- 8.7: CTRL_REG2 (21h);
- 8.8: CTRL_REG3 (22h)
- 8.12: STATUS_REG (27h),
- 8.18: FIFO_CTRL (2Eh),
- 8.19: FIFO_STATUS (2Fh).
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LPS25HB
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