CO2 Click

How does it work?

CO2 Click as its foundation uses the STC31, a gas concentration sensor for high range, accurate CO2 measurements designed for high-volume applications from Sensirion. The STC31 is based on a revolutionized thermal conductivity measurement principle, which results in superior repeatability and long-term stability. By relying on the thermal conductivity technology, the sensor offers an ultra-low power consumption, making the STC31 the perfect choice for applications where reliability is key.

The accuracy of the STC31 is 0.5 vol%, and ±3% of the measured value, while the sensor response time is faster than 1 second. The outstanding performance of these sensors is based on Sensirion’s patented CMOSens® Technology, which combines the sensor element, signal processing, and digital calibration on a small CMOS chip. The well-proven CMOSens® Technology represents the ideal choice for demanding and cost-sensitive OEM applications.

CO2 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Standard Mode operation with a clock frequency up to 100kHz, Fast Mode up to 400kHz, and Fast Mode Plus up to 1MHz. Besides, it also allows the choice of the three least significant bits of its I2C slave address by positioning the SMD jumper labeled as ADDR SEL to an appropriate position providing the user with a choice of 4 I2C Slave addresses.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use 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 CO2 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	NC
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

CO2 Click electrical specifications

Software Support

We provide a library for the CO2 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 CO2 Click driver.

Key functions

• co2_get_id Read device and serial ID’s.

• co2_set_reference Set device refrence values for gas calculation.

• co2_read_gas Read CO2 concentration and temperature value.

Example Description

This example showcases ability of Click board™. It reads ID’s configures device for operation work and reads CO2 gas concentration in air and temperature of IC every second.

 void application_task ( void ) 
 { 
     float gas_data = 0; 
     float temp_data = 0; 

     if ( CO2_OK == co2_read_gas( &co2, &gas_data, &temp_data ) ) 
     { 
         log_printf( &logger, " > CO2[%%]: %.2frn", gas_data ); 
         log_printf( &logger, " > Temperature[degC]: %.2frn", temp_data ); 
         Delay_ms( 1000 ); 
     } 

     Delay_ms( 1 ); 
 }

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.CO2

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.