30 min

Achieve accurate pressure measurements with BMP384 and STM32F413RH

Breathe easy!

Pressure 18 Click with UNI Clicker

Published Mar 11, 2023

Click board™

Pressure 18 Click

Development board

UNI Clicker


NECTO Studio



Barometric pressure data logger for every application



Hardware Overview

How does it work?

Pressure 18 Click is based on the BMP384, a high accuracy, low-power, and low noise 24-bit absolute barometric pressure sensor from Bosch Sensortec. The BMP384 comprises a piezo-resistive pressure sensing element and a mixed-signal ASIC that performs A/D conversions and provides the conversion results alongside sensor-specific compensation data through a digital interface. It also provides the highest flexibility and can be adapted to the requirements regarding accuracy, measurement time, and power consumption by selecting many possible combinations of sensor settings. The BMP384 is very accurate, covering a wide measurement pressure range from 300hPa to 1250hPa, alongside a relative accuracy of ±9Pa (equivalent to ±75cm difference in altitude), the typical absolute accuracy of ±50Pa, and a temperature coefficient offset of ±1Pa/K. This feature makes it suitable for water-level

detection and differential barometric pressure measurements. This sensor operates in three power modes: Sleep, Normal, and Forced Mode. The Normal Mode comprises automated perpetual cycling between an active measurement period and an inactive Standby period. In Sleep Mode, no measurements are being performed, while in Forced Mode, a single measurement performs. When a measurement is finished, the BMP384 returns to Sleep Mode. Also, oversampling settings are available, ranging from ultra-low power to the highest resolution set to adapt the Click board™ to the target application. Pressure 18 Click allows using both I2C and SPI interfaces with a maximum frequency of 3.4MHz for I2C and 10MHz for SPI communication. The selection can be made by positioning SMD jumpers labeled as COMM SEL in an appropriate position. Note that all the jumpers'

positions must be on the same side, or the Click board™ may become unresponsive. While the I2C interface is selected, the BMP384 allows choosing the least significant bit (LSB) of its I2C slave address using the SMD jumper labeled ADDR SEL. This Click board™ also possesses an additional interrupt pin, routed to the INT pin on the mikroBUS™ socket, indicating when a specific interrupt event occurs, such as FIFO overflow, data-ready, and more. This Click board™ can only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Pressure 18 Click top side image
Pressure 18 Click lateral side image
Pressure 18 Click bottom side image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Chip Select
SPI Clock
Power Supply
I2C Clock
I2C Data

Take a closer look


Pressure 18 Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
Thermo 28 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
UNI Clicker MB 1 - upright/with-background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for Pressure 18 Click driver.

Key functions:

  • pressure18_get_int_pin This function returns the INT pin logic state.

  • pressure18_read_data This function reads the sensor measurements data: pressure in Pascals and temperature in Celsius.

  • pressure18_soft_reset This function performs the software reset feature.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * @file main.c
 * @brief Pressure 18 Click example
 * # Description
 * This example demonstrates the use of Pressure 18 click board by reading and displaying
 * the pressure and temperature measurements.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 * ## Application Task
 * Waits for the data ready interrupt and then reads the pressure and temperature data
 * and displays them on the USB UART every 320ms approximately.
 * @author Stefan Filipovic

#include "board.h"
#include "log.h"
#include "pressure18.h"

static pressure18_t pressure18;
static log_t logger;

void application_init ( void )
    log_cfg_t log_cfg;  /**< Logger config object. */
    pressure18_cfg_t pressure18_cfg;  /**< Click config object. */

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    pressure18_cfg_setup( &pressure18_cfg );
    PRESSURE18_MAP_MIKROBUS( pressure18_cfg, MIKROBUS_1 );
    err_t init_flag  = pressure18_init( &pressure18, &pressure18_cfg );
    if ( ( I2C_MASTER_ERROR == init_flag ) || ( SPI_MASTER_ERROR == init_flag ) )
        log_error( &logger, " Communication init." );
        for ( ; ; );
    if ( PRESSURE18_ERROR == pressure18_default_cfg ( &pressure18 ) )
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    log_info( &logger, " Application Task " );

void application_task ( void )
    if ( pressure18_get_int_pin ( &pressure18 ) )
        float pressure, temperature;
        if ( PRESSURE18_OK == pressure18_read_data ( &pressure18, &pressure, &temperature ) )
            log_printf ( &logger, " Pressure: %.1f mBar\r\n", pressure * PRESSURE18_PA_TO_MBAR );
            log_printf ( &logger, " Temperature: %.2f C\r\n\n", temperature );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

// ------------------------------------------------------------------------ END

Additional Support