Pressure 21 Click

Pressure 21 Click is a compact add-on board that contains a board-mount pressure sensor. This board features the BMP581, an absolute barometric pressure sensor from Bosch Sensortec. The BMP581 provides a relative accuracy of ±6Pa and typical absolute accuracy of ±30Pa with ultra-low noise, low power consumption, and temperature stability alongside programmable output: temperature-only or both pressure and temperature (pressure-only is not supported). It converts output data into a 24-bit digital value and sends the information via a configurable host interface that supports SPI and I2C serial communications. It measures pressure from 30kPa up to 125kPa over a wide operating temperature range.

Click Product page

Click library

• Author : Stefan Filipovic
• Date : Jul 2022.
• Type : I2C/SPI type

Software Support

We provide a library for the Pressure 21 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for Pressure 21 Click driver.

Standard key functions :

• pressure21_cfg_setup Config Object Initialization function.

  void pressure21_cfg_setup ( pressure21_cfg_t *cfg );

• pressure21_init Initialization function.

  err_t pressure21_init ( pressure21_t *ctx, pressure21_cfg_t *cfg );

• pressure21_default_cfg Click Default Configuration function.

  err_t pressure21_default_cfg ( pressure21_t *ctx );

Example key functions :

• pressure21_get_int_pin This function returns the INT pin logic state.

  uint8_t pressure21_get_int_pin ( pressure21_t *ctx );

• pressure21_get_sensor_data This function reads the sensor measurements data: pressure in Pascals and temperature in Celsius.

  err_t pressure21_get_sensor_data ( pressure21_t *ctx, float *pressure, float *temperature );

• pressure21_write_register This function writes a desired data to the selected register.

  err_t pressure21_write_register ( pressure21_t *ctx, uint8_t reg, uint8_t data_in );

Example Description

This example demonstrates the use of Pressure 21 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.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    pressure21_cfg_t pressure21_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.
    pressure21_cfg_setup( &pressure21_cfg );
    PRESSURE21_MAP_MIKROBUS( pressure21_cfg, MIKROBUS_1 );
    err_t init_flag = pressure21_init( &pressure21, &pressure21_cfg );
    if ( ( I2C_MASTER_ERROR == init_flag ) || ( SPI_MASTER_ERROR == init_flag ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    if ( PRESSURE21_ERROR == pressure21_default_cfg ( &pressure21 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }

    log_info( &logger, " Application Task " );
}

Application Task

Waits for the data ready interrupt and then reads the pressure and temperature data and displays them on the USB UART approximately once per second.

void application_task ( void )
{
    if ( pressure21_get_int_pin ( &pressure21 ) )
    {
        float pressure, temperature;
        if ( PRESSURE21_OK == pressure21_get_sensor_data ( &pressure21, &pressure, &temperature ) )
        {
            log_printf ( &logger, " Pressure: %.2f mBar\r\n", pressure * PRESSURE21_PA_TO_MBAR );
            log_printf ( &logger, " Temperature: %.2f C\r\n\n", temperature );
        }
    }
}

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Pressure21

Additional notes and informations

Depending on the development board you are using, you may need USB UART Click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MikroElektronika compilers.