Intermediate
30 min
0

Explore the newest pressure data with BMP388 and PIC18F46K22

The future of pressure measurement

Pressure 5 Click with EasyPIC v8

Published Oct 13, 2023

Click board™

Pressure 5 Click

Development board

EasyPIC v8

Compiler

NECTO Studio

MCU

PIC18F46K22

With our digital sensors, you can monitor and control pressure variations in real time, ensuring safety and precision in your applications

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Hardware Overview

How does it work?

Pressure 5 Click is based on the BMP388, a digital pressure sensor, from Bosch Sensortec. This sensor consists of a piezo-resistive pressure sensing element and a mixed-signal ASIC which performs A/D conversions and provides the conversion results through a digital interface. This advanced MEMS technology offers a high measurement precision of 0.08hPa, as well as low TOC (thermal coefficient) of only 0.75 Pa/K. The sensor is enclosed in a small metal lid housing and is highly resilient: it can operate in a range of 300 hPa to 1250 hPa but can withstand up to 20,000 hPa before the membrane breaks down. The BMP388 offers a set of pressure and temperature measurement options. It can be programmed to skip either thermal or pressure measurement, allowing faster measurement of the required property. The low TOC of only 0.75Pa/K allows reading of the pressure with very small drift over temperature. Resolution of 0.08hPa allows calculating of the altitude with the accuracy of about 66 cm, which is ideal for indoor navigation applications (drones, flying toy models, and similar). The IIR filter is especially useful for indoor usage, allowing filtering of some short-term disturbances, such as slamming doors or windows. FIFO buffer allows for an optimization of the host firmware, reducing the data traffic through the

communication interface. It has 512 bytes and it is backed up by an interrupt engine, which can trigger an interrupt event when the buffer is full, or when the watermark level is reached. Also, the behavior of the FIFO buffer can be programmed to either skip new data once it is full or to overwrite the oldest data. The interrupt is available over the INT pin, and can be used to further optimize the host firmware (i.e. to reduce the power consumption by utilizing the INT pin to wake up the host MCU). Besides FIFO events, the INT pin also signals when there is a new data available at the output register (Data Ready event). This sensor consists of a mixed signal front-end (ASIC) and a piezo-sensitive pressure sensing element. The ASIC contains a low-noise 24-bit A/D converter, along with the digital signal processing section. The measurement data is available either over the I2C or the SPI interface. Pressure 5 click offers a choice between these two interfaces. The selection can be done by positioning SMD jumpers labeled as COMM SEL to an appropriate position. Note that all the jumpers must be placed to the same side, else the Click board™ may become unresponsive. While the I2C interface is selected, the BMP388 allows the choice of the least significant bit (LSB) of its I2C slave address. This can be done by using the SMD jumper

labeled as ADDR SEL. The overall power consumption depends on several factors, such as the oversampling value, measurement rate, power mode, standby duration, and so on. Bosh Sensortech recommends a set of operational parameters for different applications, in the form of a table, in the BMP388 datasheet. In general, this sensor allows several power modes, regardless of the selected measurement parameters. When the measurement is completed, raw ADC values will be available in the output registers. However, to obtain actual pressure and temperature readings, a compensation algorithm needs to be applied. A set of compensation parameters is available in the non-volatile memory of the BMP388 device. These compensation parameters take into account slight differences between the produced samples and each BMP388 device has its own set of parameters. The BMP388 datasheet offers detailed instructions on how to apply these compensating algorithms properly. However, MikroElektronika provides a library with functions which can be used for a simplified and thus faster application development. The library also contains a demo example, which demonstrates the use of these functions. The demo application can be used as a reference for a custom design.

Pressure 5 Click top side image
Pressure 5 Click bottom side image

Features overview

Development board

EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 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 v8 horizontal image

Microcontroller Overview

MCU Card / MCU

PIC18F46K22

Architecture

PIC

MCU Memory (KB)

64

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

3896

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RE0
CS
SPI Clock
RC3
SCK
SPI Data OUT
RC4
MISO
SPI Data IN
RC5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Interrupt
RB0
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

Pressure 5 Click Schematic schematic

Step by step

Project assembly

EasyPIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v8 as your development board.

EasyPIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
MCU DIP 40 hardware assembly
EasyPIC v8 DIP 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
Necto image step 8 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 Pressure 5 Click driver.

Key functions:

  • pressure5_update_coefficient - This function allows you to update the calibration coefficient

  • pressure5_get_temperature_data - This function gets temperature in Celsius

  • pressure5_get_pressure_data - This function gets pressure in mBar

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 Pressure5 Click example
 * 
 * # Description
 * This example preforms Temperature and Pressure measurement.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver init, test comunication, software reset, update
 * coefficient and configuration module for start measurement.
 * 
 * ## Application Task  
 * Reads Pressure data in [mBar] and Temperature data in [C]. 
 * Logs all data to the USBUART every 2 seconds.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "pressure5.h"

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

static pressure5_t pressure5;
static log_t logger;

static float temperature;
static float pressure;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    pressure5_cfg_t cfg;
    PRESSURE5_RETVAL init_ret;

    /** 
     * 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.

    pressure5_cfg_setup( &cfg );
    PRESSURE5_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    pressure5_init( &pressure5, &cfg );
    pressure5_default_cfg( &pressure5 );
}

void application_task ( void )
{
    //  Task implementation.

    temperature = pressure5_get_temperature_data ( &pressure5 );
    log_printf( &logger, "Temperature: %.2f C\r\n", temperature );
    
    pressure = pressure5_get_pressure_data ( &pressure5 );
    log_printf( &logger, "Pressure: %.2f mBar\r\n ", pressure );
    log_printf( &logger, "\r\n" );
    
    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources