Get accurate pressure data with MPRLS0025PA00001A and ATmega1284P
Beyond the gauge: Digital sensors redefine accuracy
Published Nov 01, 2023
Click board™
Pressure 8 Click
Dev Board
EasyAVR v7
Compiler
NECTO Studio
MCU
ATmega1284P
Whether you're in manufacturing or research, our digital pressure sensors deliver the edge you need to excel in a competitive world
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Hardware Overview
How does it work?
Pressure 8 Click is based on the MPRLS0025PA00001A, an accurate compensated absolute pressure sensor from Honeywell. This sensor offers a range of highly useful features. The most distinctive feature of this sensor is its high accuracy and ability to output compensated 24-bit values over the I2C interface. This MPR series sensor integrates an ASIC (Application Specific Integrated Circuit), along with the piezoresistive silicon pressure sensor. Thanks to the integrated ASIC, this sensor can output 24-bit compensated measurements within the range of 0 psi to 25 psi (0 to about 172kPa), and temperatures from 0 °C to 50 °C. Due to the silicone gel protection, it can be used with a variety of liquid media. The casing of the MPRLS0025PA00001A sensor is built of stainless steel, preventing the rust formation. All the electronic components within the sensor are protected by a silicone gel, allowing the sensor to be used with a wide variety of liquid media. It can be used to mesure absolute pressure values up to 25 psi, or about 172 kPa. However, the sensor can be exposed up to 60 psi (about 414 kPa) of overpressure, without causing permanent damage. The absolute maximum pressure allowed is 120 psi (about 825 kPa). Exposing the sensor to absolute maximum pressure will damage it
permanently, and it will not be functional anymore. Pressure beyond this point will physically destroy the sensor, resulting in possible leakage. There is a range of errors common to any sensor of this type, that affect its accuracy. The term "Total Error Band" (TEB) is used within the datasheet of the MPRLS0025PA00001A sensor to better illustrate its accuracy, considering all of the pressure measurement errors, combining them into a single parameter. The datasheet specifies the TBD of the sensor to be ±1.5. It also offers a transfer function, which can e used to calculate the output pressure value based on a 24-bit result, provided over the I2C interface. The first byte after the conversion command is sent over the I2C interface is the content of the status register. It contains a BUSY flag (bit 5) among other status bits. It indicates the end of conversion, so the software should poll the status byte and wait this bit to be reset. Another, much simpler method is to use the EOC (End of Conversion) pin, routed to the mikroBUS™ INT pin, labeled as EOC on this Click Board™. This pin allows much simpler software routine to be written, using the EOC pin to trigger an interrupt on the host microcontroller (MCU). A HIGH logic level on this pin indicates that the conversion is finished. Lastly, the user can
simply wait at least 5ms for the conversion to complete, before issuing another command. The RES pin of the sensor is used to perform a hardware reset. This pin is routed to the mikroBUS™ RST pin, and a logic LOW pulse on this pin will reset the sensor IC. It is pulled to a HIGH logic level by an onboard resistor preventing it to float and uncontrollably reset the sensor, if the corresponding pin is tri-stated on the host MCU. The EOC event is also signaled visually, by a LED labeled as READY. This LED provides visual feedback about the status of the conversion: when lit, it indicates that the conversion is ended, and the measurement conversion data can be retrieved over the I2C interface. Pressure 8 click is supported by the mikroSDK compatible library of functions that encapsulate all the necessary conversions and status checking, returning the measured value converted into physical units, directly. This vastly simplifies and speeds up the development process. This Click Board™ uses the I2C communication interface. It has pull-up resistors connected to the mikroBUS™ 3.3V rail. Proper conversion of logic voltage levels should be applied before the Click board™ is used with MCUs operated with 5V.
Features overview
Development board
EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. 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, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more
efficiently than ever. Each part of the EasyAVR 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 a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V 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 which cover a wide range of 16-bit AVR MCUs. EasyAVR 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.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
16384
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.
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.
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.
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".
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.
Software Support
Library Description
This library contains API for Pressure 8 Click driver.
Key functions:
pressure8_get_pressure- Functions for get Pressure datapressure8_get_device_status- Functions for get device statuspressure8_set_psi_range- Functions for set PSI range
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 Pressure8 Click example
*
* # Description
* This application reads pressure data.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization device and logger module, reset device and set PSI range.
*
* ## Application Task
* Reads Pressure data and this data logs every 1 sec.
*
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "pressure8.h"
// ------------------------------------------------------------------ VARIABLES
static pressure8_t pressure8;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
pressure8_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.
pressure8_cfg_setup( &cfg );
PRESSURE8_MAP_MIKROBUS( cfg, MIKROBUS_1 );
pressure8_init( &pressure8, &cfg );
pressure8_device_reset( &pressure8 );
pressure8_set_psi_range( 0, 25 );
}
void application_task ( void )
{
float pressure_data;
pressure_data = pressure8_get_pressure( &pressure8, PRESSURE8_DATA_IN_mBar );
log_printf( &logger, "--- Pressure data : %f mBar\r\n", pressure_data );
Delay_ms( 1000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
