Pressure 21 Click

How does it work?

Pressure 21 Click as its foundation uses the BMP581, a high accuracy, low power, barometric pressure, and temperature sensor solution from Bosch Sensortec. The BMP581 provides proper absolute pressure and temperature measurements, due to on-chip linearization and temperature compensation, from 30kPa to 125kPa over a wide operating temperature range from -40 to +85°C. It also 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).

The BMP581 operates in three power modes: Sleep, Normal, and Forced Mode. The Normal Mode comprises automated perpetual cycling between an active measurement period and an inactive Standby period. In Sleep Mode, no measurements are being performed, while in Forced Mode, a single measurement performs. When a measurement is finished, the BMP581 returns to Sleep Mode. Also, a set of oversampling settings are available, ranging from ultra-low power to highest resolution setting to adapt the Click board™ to the target application.

Pressure 21 Click allows using both I2C and SPI interfaces with a maximum frequency of 1MHz for I2C and 10MHz for SPI communication. The selection can be made by positioning SMD jumpers labeled as COMM SEL in an appropriate position. Note that all the jumpers’ positions must be on the same side, or the Click board™ may become unresponsive. While the I2C interface is selected, the BMP581 allows choosing the least significant bit (LSB) of its I2C slave address using the SMD jumper labeled ADDR SEL. This Click board™ also possesses an additional interrupt pin, routed to the INT pin on the mikroBUS™ socket, indicating when a specific interrupt event occurs, such as FIFO overflow, the threshold over/underrun, data-ready, and more.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

Specifications

Pinout diagram

This table shows how the pinout on Pressure 21 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	INT	Interrupt
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	SCL	I2C Clock
SPI Data IN	SDI	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Pressure 21 Click electrical specifications

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.

Key functions

• pressure21_get_int_pin This function returns the INT pin logic state.

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

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

Example Description

This example demonstrates the use of Pressure 21 Click board™ by reading and displaying the pressure and temperature measurements.

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 mBarrn", pressure * PRESSURE21_PA_TO_MBAR ); 
             log_printf ( &logger, " Temperature: %.2f Crnn", 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.

mikroSDK

This Click board™ is supported with mikroSDK – MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.