30 min

Monitor pressure variations with SDP31-500PA and PIC18F57Q43 in various control processes

Differential pressure sensors: Where science meets real-world solutions

Diff Press 2 Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

Diff Press 2 Click

Dev Board

Curiosity Nano with PIC18F57Q43


NECTO Studio



Explore the principles and technology behind differential pressure sensors, highlighting their critical role in modern measurement systems



Hardware Overview

How does it work?

Diff Press 2 Click is based on the SDP31-500PA, a highly versatile differential pressure sensor designed for high-volume applications from Sensirion. It builds on the next-generation CMOSens® sensor chip at the heart of Sensirion’s new differential pressure and flows sensing platform. It features fast measurement speed, excellent accuracy, and long-term stability, has no zero-point drift, and offers an ultra-low power consumption, making the SDP31-500PA the perfect choice for applications where accurate and reliable pressure monitoring is essential. The SDP31-500PA is very flexible regarding

measurement speed. This flexibility allows for optimizing the sensor’s performance for a specific application and for adapting the sensor to different use cases. For example, the sensor detects the smallest and quickest changes in one use case, whereas, in another mode, the sensor can measure in larger intervals while consuming only a little energy. Diff Press 2 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Fast Mode up to 400kHz. Besides, the SDP31-500PA allows choosing the least significant bit (LSB) of its I2C slave address

using the SMD jumper labeled ADDR SEL. It also possesses an additional interrupt signal, routed on the INT pin of the mikroBUS™ socket labeled as INT, indicating when a specific interrupt event occurs, such as whether new measurement results are available. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Diff Press 2 Click top side image
Diff Press 2 Click bottom side image

Features overview

Development board

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU




MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


You complete me!


Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Power Supply
I2C Clock
I2C Data
Power Supply

Take a closer look


Diff Press 2 Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Curiosity Nano with PICXXX Access MB 1 - upright/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
PIC18F57Q43 Curiosity MCU Step 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 Diff Press 2 Click driver.

Key functions:

  • diffpress2_get_id - Reads device ID's

  • diffpress2_reset - Reset device

  • diffpress2_trigger_measurement - Pressure and temperature reading

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 DiffPress2 Click example
 * # Description
 * This example application showcases ability for device
 * to read and calculate mass flow or diff press pressure
 * in Pascals and temperature in degrees Celsius.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initialization of module communication(I2C, UART) and 
 * additional interrupt pin. Resets device and reads
 * serial and product ID's and logs them.
 * ## Application Task
 * Read and calculate differential in Pascal and temperature 
 * in degrees Celsius every 300ms.
 * @author Luka Filipovic

#include "board.h"
#include "log.h"
#include "diffpress2.h"

static diffpress2_t diffpress2;
static log_t logger;

void application_init ( void ) 
    log_cfg_t log_cfg;  /**< Logger config object. */
    diffpress2_cfg_t diffpress2_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.
    diffpress2_cfg_setup( &diffpress2_cfg );
    DIFFPRESS2_MAP_MIKROBUS( diffpress2_cfg, MIKROBUS_1 );
    err_t init_flag = diffpress2_init( &diffpress2, &diffpress2_cfg );
    if ( I2C_MASTER_ERROR == init_flag ) 
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );

    if ( diffpress2_default_cfg ( &diffpress2 ) ) 
        log_error( &logger, " Default configuration." );
        for ( ; ; );

    log_printf( &logger, " > Product ID: 0x%.8LX\r\n", diffpress2.product_id );
    log_printf( &logger, " > Serial ID: 0x%.8LX%.8LX\r\n", 
                diffpress2.serial_id[ 0 ], diffpress2.serial_id[ 1 ] );

    log_info( &logger, " Application Task " );

void application_task ( void )
    float pressure;
    float temperature;

    if ( diffpress2_trigger_measurement( &diffpress2, DIFFPRESS2_CMD_TRIGGER_MEAS_DIFF_PRESS, 
                                         &pressure, &temperature ) )
        log_error( &logger, " Read data." );
        log_printf( &logger, " > Pressure[Pa]: %.2f\r\n", pressure );
        log_printf( &logger, " > Temperature[degC]: %.2f\r\n", temperature );
        log_printf( &logger, "*************************************\r\n" );

    Delay_ms( 300 );

void main ( void ) 
    application_init( );

    for ( ; ; ) 
        application_task( );

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

Additional Support