PRESSURE 9 CLICK
PID: MIKROE-3441
Weight: 23 g
Pressure 9 click is a digital barometric air pressure sensor Click board™. It is equipped
with the DPS422, barometric air pressure sensor, based on a capacitive sensor
element. Besides the pressure, this sensor can also measure temperature.
Measurement data is available over the I2C or SPI interface, along with the factory
calibrated coefficients, used for high-accuracy data conversion. The device also
features 32 words-long FIFO buffer, low power consumption, and very high precision,
thanks to an integrated 24-bit A/D converter. It can be used within the pressure range
from 300 to 1200hPa and temperature in the range from -40⁰C to +85⁰C.
Pressure 9 Click is supported by a mikroSDK compliant library, which includes functions
that simplify software development. This Click board™ comes as a fully tested product,
ready to be used on a system equipped with the mikroBUS™ socket.
The DPS422 is designed with the low-power consumption in mind, has a very small
size, and requires a low number of external components. These features make the
DPS422 a perfect choice for an IoT or battery-powered application. Therefore, Pressure
9 click can be used as a tool for development of various pressure-based IoT
applications, as well as other applications where the power consumption and
constrained space could be a problem: portable weather stations, room temperature
control, applications related to elevation gain and vertical speed detection, sportsrelated wearables, and similar.
HOW DOES IT WORK?
Pressure 9 click features the DPS422, a digital barometric air pressure sensor,
by Infineon. It can be used to measure absolute pressure values from 300 to 1200hPa.
The sensor contains a highly accurate capacity-based Micro Electro-Mechanical Sensor
(MEMS), along with a high resolution 24-bit sigma-delta A/D converter (ADC). The
MEMS also features a set of factory calibration parameters, stored into its OTP
memory. They allow high-precision pressure and temperature data conversions to be
performed, enabling results in physical units. By adjusting the oversampling ratio, the
developer can find a perfect balance between the accuracy, speed (output data rate),
and power consumption, in accordance to the application requirements.
MEMS consists a set of tubular vacuum cells, covered by membranes. By applying a
pressure, capacitance of the cell is changed proportionally. Several vacuum cells are
connected in parallel, allowing for better sensitivity and less noise. The capacitance of
the cells is measured and converted to a voltage which is sampled by the internal 24-bit
ADC. The result is available over I2C or SPI interface, depending on the position of the
COMM SEL jumpers. The conversion formula is then applied to the raw result value,
providing pressure and temperature values in human readable format.
Pressure 9 click supports both SPI and I2C communication interfaces, allowing it to be
used with a wide range of different MCUs. The communication interface can be chosen
by moving SMD jumpers grouped under the COM SEL to an appropriate position (SPI
or I2C). The slave I2C address can also be configured by a SMD jumper, when
operated in the I2C mode: a SMD jumper labeled as ADD SEL is used to set the least
significant bit (LSB) of the I2C address. When set to 0, the 7-bit I2C slave address
becomes 0b1110110x. If set to 1, the address becomes 0b1110111x. The last digit (x)
is the R/W bit. Please note that each jumper should be moved to the same position,
else the communication with the host MCU may not be possible.
One of distinctive features of the DPS422 is the FIFO buffer with 32 slots, allowing to
buffer both pressure and temperature readings. The FIFO buffer can be used as a
temporary storage for the incoming data, allowing for reduced data traffic through the
communication bus. The FIFO buffer can be very useful for writing an optimized MCU
firmware. The least significant bit (LSB) of the result stored within the FIFO buffer,
determines if the stored data represents pressure, or temperature (1 is used for
pressure, 0 for temperature). A bit within the FIFO status register indicates if the buffer
is full or if the watermark level has been reached. The FIFO buffer can also be disabled,
allowing data to be fetched from the output registers, directly.
Pressure and thermal data are available at the output, in 24-bit, two’s complement
format. To convert the raw data into a human-readable format, the firmware of the host
MCU has to obtain the calibration data. Calibration coefficients are then used within
pressure or temperature conversion formulas. The required formulas can be found
within the datasheet of the DPS422. However, this Click board™ comes with the
mikroSDK compatible library of functions that simplify the firmware development. The
developer is able to use simple function calls, which perform all the necessary data
conversion, returning the pressure and thermal data in human readable format.
This Click Board™ is designed to be operated by 3.3V logic levels only. A proper logic
voltage level translation should be performed before the Click board™ is used MCUs
which are operated at 5V.
SPECIFICATIONS
Type
Pressure / Altitude
Applications
A perfect tool for development of various pressure-based IoT
applications, as well as other low-power and space-constrained
applications: portable weather stations, room temperature control,
applications related to elevation gain and vertical speed detection,
sports-related wearables, and similar.
On-board
modules
DPS422, a digital barometric air pressure sensor, by Infineon.
Key Features
24-bit conversion, high precision, low power consumption, low
count of external components required, both pressure and
temperature data, factory programmed calibration parameters,
perfect for IoT based applications.
Interface
I2C,SPI
Input Voltage
3.3V
Click board
size
M (42.9 x 25.4 mm)
PINOUT DIAGRAM
This table shows how the pinout on Pressure 9 click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
1
AN
PWM
16
NC
NC
2
RST
INT
15
NC
CS
3
CS
RX
14
NC
SPI Clock
SCK
4
SCK
TX
13
NC
SPI Data OUT
SDO
5
MISO
SCL
12
SCL
I2C Clock
SPI Data IN
SDI
6
MOSI
SDA
11
SDA
I2C Data
Control IN 2
Power Supply
3.3V
7
3.3V
5V
10
NC
Ground
GND
8
GND
GND
9
GND
Ground
PRESSURE 9 CLICK ELECTRICAL SPECIFICATIONS
Description
Min
Typ
Max
Unit
Pressure range
300
1200
hPa
Temperature range
-40
+85
˚C
ONBOARD SETTINGS AND INDICATORS
Label
Name
Default
Description
LD1
PWR
-
JP1,
JP3
COM SEL
Left
Communication interface selection: left position
I2C, right position SPI
JP4
ADDR SEL
Left
Slave I2C address LSB selection: left position 0,
right position 1
Power LED Indicator
SOFTWARE SUPPORT
We provide a library for the Pressure 9 click on our LibStock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo can run
on all the main MikroElektronika development boards.
Library Description
The library initializes and defines the I2C or SPI bus driver and drivers that offer a
choice for writing data in register and reads data form register. The library includes
function for read Pressure data in mBar and Temperature data in C. The user also has
the function for update all calibration coefficients, function for configuration register and
functions for get Pressure and Temperature raw data.
Key functions:
float pressure9_getTemperatureData() - Temperature data.
float pressure9_getPressureData() - Pressure data.
void pressure9_updateCalculationCoefficient() - Update all calibration coefficients.
Examples description
The application is composed of the three sections :
System Initialization - Initializes I2C or SPI module and sets CS pin as OUTPUT for select
comunication.
Application Initialization - Initialization driver init, test comunication, software reset, configuration
module for measurement and calls the function to update calibration coefficients - this function must
be called before the measurement starts.
Application Task - Reads Temperature data in [C] and Pressure data in [mBar] and this data logs to
the USBUART every 1 sec.
void applicationTask()
{
float Temperature;
float Pressure;
char demoText[ 50 ] = {0};
Pressure = pressure9_getPressureData();
FloatToStr(Pressure, demoText);
mikrobus_logWrite(" ‐‐ Pressure : ", _LOG_TEXT);
mikrobus_logWrite(demoText, _LOG_LINE);
Temperature = pressure9_getTemperatureData();
FloatToStr(Temperature, demoText);
mikrobus_logWrite(" ‐‐ Temperature : ", _LOG_TEXT);
mikrobus_logWrite(demoText, _LOG_LINE);
mikrobus_logWrite("‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐", _LOG_LINE);
Delay_ms( 500 );
}
The full application code, and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
I2C
SPI
UART
Conversions
Additional notes and informations
Depending on the development board you are using, you may need USB UART
click, USB UART 2 click or RS232 click to connect to your PC, for development systems
with no UART to USB interface available on the board. The terminal available in all
MikroElektronika compilers, or any other terminal application of your choice, can be
used to read the message.
MIKROSDK
This click board is supported with mikroSDK - MikroElektronika Software Development
Kit. To ensure proper operation of mikroSDK compliant click board demo applications,
mikroSDK should be downloaded from the LibStock and installed for the compiler you
are using.
For more information about mikroSDK, visit the official page.
https://www.mikroe.com/proximity‐7‐click//4‐9‐19