Intermediate
30 min
0

Navigate the intricacies of fluid dynamics and airflow control with confidence, thanks to the MPXV7007DP and PIC18LF45K42

From flow rate monitoring to filter performance analysis

Diff Press Click with EasyPIC v7

Published Nov 01, 2023

Click board™

Diff Press Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18LF45K42

Experience a new level of precision in differential pressure measurement with our innovative sensor, built to streamline your operations and enhance decision-making

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Hardware Overview

How does it work?

Diff Press Click is based on the MPXV7007DP, a highly advanced, integrated monolithic differential pressure sensor from NXP Semiconductor. This sensor features piezo-resistive MEMS sensing element, combined with the integrated electronic components that allow it to achieve a high degree of linearity, as well a very low drift over temperature. It can be used to measure the differential pressure within the range of ±7kPa. The casing of the sensor contains two small tubes referred to as "ports" in the datasheet. They can be used to easily interface the sensor with various components which produce gas pressure, preventing leakage that might appear if the sealing is not good enough. The sensor is guaranteed to operate according to specifications only if used in dry air conditions. Please refer to the datasheet of the MPXV7007DP for more details. The MPXV7007DP sensor has two ports in a form of two tubes for simplified attachment to a pressurized system, as already discussed. One of these ports is designated as the Pressure side, while the other one is designated as the

Vacuum side. The Pressure side is protected by a fluoro-silicone gel which protects the die from harsh media. However, the sensor is designed to be used with both positive and negative differential pressure values, depending on the application requirements (P1 > P2 or P2 > P1). The sensor outputs half the maximum output voltage when there is no pressure difference between two input ports. As the difference increases, the voltage either decreases down to 0V (-7kPa) or increases up to its maximum value of 4.5V, typically (+7kPa). The internal calibration and a signal conditioning circuit ensure that the output voltage changes linearly with the pressure difference. The MPXV7007DP datasheet offers a graphic diagram, displaying the output voltage in respect to the pressure difference. Besides the diagram, the datasheet also offers the transfer function for the sensor output voltage, in a form of an equation. All the parameters can be found within the datasheet, if a precise calculation of the pressure is required. Besides the MPXV7007DP, Diff Press click utilizes an additional IC. It uses the

MCP3221, a 12-bit successive approximation A/D converter (ADC) with I2C Interface, from Microchip. It is used to sample the output voltage from the sensor, providing data for the microcontroller (MCU) or some other device capable of communicating over the I2C bus. The voltage is sampled to a 12-bit value using the 5V mikroBUS™ rail as the voltage reference. The relation between the ADC value and the voltage on the output pin is given by the formula: VOUT = 5/4096 x VAL. Where VOUT is the output voltage of the sensor and VAL is the 12-bit ADC value. However, the Click board™ is supplied with the mikroSDK library which contains functions for data conversion, providing readings in physical units. Two resistors are used to pull up I2C bus lines. An onboard jumper labeled as VCC SEL offers selection of the I2C communication voltage level by connecting these resistors either with 3.3V or 5V mikroBUS™ rail. This jumper can be used to interface the Click board™ with both 3.3V and 5V MCUs, allowing a wide range of different MCUs to be used with the Click board™.

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

Features overview

Development board

EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyPIC v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of

the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use various external power sources, including an external 12V power supply, 7-23V AC or 9-32V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B) connector. Communication options such as

USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from PIC10F, PIC12F, PIC16F, PIC16Enh, PIC18F, PIC18FJ, and PIC18FK families. EasyPIC v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyPIC v7 horizontal image

Microcontroller Overview

MCU Card / MCU

PIC18LF45K42

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Diff Press Click Schematic schematic

Step by step

Project assembly

EasyPIC v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7 as your development board.

EasyPIC v7 front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyPIC v7 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Diff Press Click driver.

Key functions:

  • diffpress_get_adc_data - Gets adc data function

  • diffpress_get_pressure_difference - Gets pressure difference function

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 
 * \brief DiffPress Click example
 * 
 * # Description
 * This demo application is made for measuring differential pressure.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes device and logger module.
 * 
 * ## Application Task  
 * Logs pressure difference data.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "diffpress.h"

// ------------------------------------------------------------------ VARIABLES

static diffpress_t diffpress;
static log_t logger;
float pressure_difference;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    diffpress_cfg_t cfg;

    /** 
     * 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.

    diffpress_cfg_setup( &cfg );
    DIFFPRESS_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    diffpress_init( &diffpress, &cfg );
}

void application_task ( void )
{
    pressure_difference = diffpress_get_pressure_difference( &diffpress );

    log_printf( &logger, "-- Pressure difference  : %f kPa\r\n", pressure_difference );

    Delay_ms( 500 );
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

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

Additional Support

Resources