Altitude 2 click
PID: MIKROE‐3030
Weight: 24 g
Altitude 2 click is a high‐resolution barometric pressure sensor Click board™. It provides
very accurate measurements of temperature and atmospheric pressure, which can be used
to calculate the altitude with a very high resolution of 20cm per step. Besides that, the
device also includes features such as the ultra‐low noise delta‐sigma 24bit ADC, low power
consumption, fast conversion times, pre‐programmed unique compensation values, and
more. Low count of external components requirement, along with the simple interface
which requires no extensive configuration programming, makes this sensor very attractive
for building altitude or air pressure measuring applications.
To measure the air pressure with a reasonable accuracy, the ambient temperature should
also be taken into the consideration. The sensor component of the Altitude 2 click provides
an accurate ambient temperature measurement, which can be used to extract the
compensated air pressure value from the readings. It can be set to work with both SPI and
I2C communication protocol, by switching a few onboard jumpers. With its low power
consumption, it is a great solution for using it in various mobile altimeter applications,
such as the bike computers, variometers, data loggers, mobile altimeter and barometer
stations, weather stations, and similar.
How does it work?
The barometric pressure sensor used on the Altitude 2 click is the MS5607‐02BA03, a
barometric pressure sensor IC with the stainless steel cap, produced by MEAS
Switzerland, a company that has a long-term experience in development of
altimeter/barometric pressure sensors. The sensor IC consists of a piezo-resistive sensor
and the analog front end with the I2C/SPI interface. The sensor is manufactured using
the advanced MEMS (Micro Electro Mechanical System) technology. It is optimized for a
precise altitude measurement, based on the atmospheric pressure and temperature
changes, in relation with altitude.
Each sensor IC is factory calibrated at two temperatures and pressures. The calibration
coefficients are stored to its 128 bit PROM area. To calculate the correct values, these
coefficients need to be used in the calculation, in order to derive real values from the
raw, uncompensated readings, referred to as D1 and D2 in the datasheet of the device.
These two raw values represent temperature and pressure measurements, converted by
the internal 24bit delta-sigma ADC.
The compensation is needed because of several reasons. The barometric pressure
measurement is influenced by a temperature and the offset value, measured at 0 Pa
(zero offset coef.); the temperature measurement itself has a coefficient that differs from
piece to piece; the altitude does not linearly depend on the barometric pressure, and so
on. For this reason, the final altitude value needs to be calculated taking into account its
compensating coefficients, referred to as C1-C6 in the datasheet.
The control of the Click board™ is very simple. After the power on, the device should be
reset by sending the RESET command, making sure that the proper PROM data is
loaded into the internal register. After this, the content of the PROM should be read by
the host MCU, also by sending a command via the communication bus. Finally, a
command to start the conversion of the uncompensated measurement can be sent to
the Altitude 2 click, which will respond with the conversion value, after the internal
conversion period is finished. This will provide all the necessary information for the host
MCU to extract the compensated values. More information about the commands and
their responses can be found in the MS5607-02BA03 datasheet.
However, MikroElektronika provides a library that contains functions compatible with
the MikroElektronika compilers, which can be used for simplified programming of the
Altitude 2 click, such as the calculation function for the altitude measurement, based on
the pressure and the temperature readings, raw values for the pressure and
temperature, as well as the compensated (actual) pressure and temperature readings.
The library also contains an example application, which demonstrates their use. This
example application can be used as a reference for custom designs.
The Click board™ offers a choice between using the I2C and SPI communication
protocol. When I2C communication protocol is selected, all jumpers labeled as the
COMM SEL, should be set to the I2C position (left). When SPI is selected, all these
jumpers should be moved to the SPI position (right). When I2C protocol is selected,
another onboard SMD jumper is used to set the LSB bit of the slave I2C address. Please
note that when selecting I2C or SPI protocol, all of the COMM SEL SMD jumpers should
be set at the same position (all to SPI, or all to I2C). Mixed position settings can result in
the unresponsiveness of the Click board™.
There are no additional pins routed from the sensor IC, other than the lines used for the
communication: SPI lines, labeled as SDI, SDO, SCK, and CS, and I2C lines, labeled as
SDA and SCL. These lines are routed to the appropriate mikroBUS™ pins, used for I2C
and SPI communication. The I2C lines, along with the CS line are pulled to a HIGH logic
level by the onboard resistors. Please note that the Click board™ supports only 3.3V
MCUs and it is not intended to be connected or controlled via the 5V MCU without a
proper level shifting circuitry.
Specifications
Type
Altitude,Pressure
Can be used for various mobile altimeter applications, such as the
Applications
bike computers, variometers, data loggers, mobile altimeter and
barometer stations, weather stations, etc.
On-board
MS5607-02BA03, a barometric pressure sensor IC with the stainless
modules
steel cap, produced by MEAS Switzerland
Low power consumption which allows mobility, high resolution with
Key Features
20cm step, high stability of the measurement readings, factory
calibrated compensation coefficients, I2C and SPI support.
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 Altitude 2 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
+3.3V
7
3.3V
5V
10
NC
GND
8
GND
GND
9
GND
SPI Chip Select
Power supply
Ground
Ground
Altitude 2 click electrical specifications
Description
Min
Typ
Max
Unit
10
-
1200
mbar
Pressure measurement resolution
0.13
-
0.024
mbar
Response time
0.5
-
8.22
ms
Temperature range
-40
-
+85
˚C
Temperature accuracy
-0.8
-
+0.8
˚C
Pressure range
Onboard settings and indicators
Label
Name
Default
LD1
PWR
-
JP1 - JP5
COMM SEL
Left
JP6
I2C ADDR
Right
Description
Power LED indicator
Selection of the communication type: left
position I2C, right position SPI
I2C slave address LSB bit selection: left position
0, right position 1
Software support
We provide a library for Altitude 2 click on our Libstock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo
application can run on all the main MikroElektronika development boards.
Library Description
The library initializes and defines I2C and SPI driver and performs the communication
with device registers by both drivers. The library offers a choice to measure the
temperature in Celsius degrees, and the pressure in mbar units. The user can determine
the oversampling ratio value for both measurements independently. For more details
check the documentation.
Key functions:
uint8_t altitude2_readPROM( uint8_t selectData, uint32_t *dataOut )- The function reads
uint8_t altitude2_setRatio( uint8_t tempRatio, uint8_t pressRatio )- The function
void altitude2_readData( float *tempData, float *pressData, float *altitudeData )-
calibration data from PROM.
determines the oversampling ratio value for temperature and pressure measurements.
The function performs temperature and pressure measurements with desired oversampling ratio
and performs the calculations that convert temperature data in Celsius value and pressure data
in mbar value. Depending on the temperature and pressure calculated values, the function
calculates the altitude value in meters.
Examples Description
System Initialization - Initializes peripherals and pins.
Application Initialization - Initializes I2C/SPI driver and performs the device reset, after which the
calibration coefficients can be read. Determines the ratio value for temperature and pressure
measurements. It is necessary to read the calibration coefficients after the device reset.
Application Task - (code snippet) - Gets temperature data in Celsius degrees and pressure data
in mbar value. Gets the calculated altitude value in meters, which depends on the temperature
and pressure measurements. Logs results on USB UART and repeats operation every 300 ms.
void applicationTask()
{
altitude2_readData( &temperature, &pressure, &altitude );
mikrobus_logWrite( "Temperature is: ", _LOG_TEXT );
FloatToStr( temperature, text );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( " Celsius", _LOG_LINE );
mikrobus_logWrite( "Pressure is: ", _LOG_TEXT );
FloatToStr( pressure, text );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( " mbar", _LOG_LINE );
mikrobus_logWrite( "Altitude is: ", _LOG_TEXT );
FloatToStr( altitude, text );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( " m", _LOG_LINE );
mikrobus_logWrite( "", _LOG_LINE );
Delay_ms( 300 );
}
The full application code, and ready to use projects can be found on our Libstock page.
mikroE Libraries used in the example:
Conversions
I2C
SPI
UART
Additional notes and information
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 by mikroSDK ‐ MikroElektronika Software Development Kit.
To ensure a proper operation of mikroSDK compliant Click board™ demo applications, the
mikroSDK package should be downloaded from the LibStock and installed for the compiler
you are using.
For more information about the mikroSDK, visit the official page.
https://www.mikroe.com/altitude‐2‐click 6‐15‐18
