Air Quality 11 Click

How does it work?

Air Quality 11 Click is based on the ENS161, a multi-gas sensor from ScioSense based on metal oxide (MOX) technology. It features four sensor elements that support both isothermal and low-power modes. This advanced sensor offers a unique capability of independently controlling the hotplate to detect a wide range of volatile organic compounds (VOCs) like ethanol, toluene, hydrogen, and oxidizing gases with enhanced sensitivity. Equipped with intelligent on-chip algorithms, the ENS161 processes raw sensor data to calculate various air quality metrics, such as TVOC- and CO2-equivalents and different air quality indices, and performs compensations for humidity and temperature.

A key feature of the ENS161 is its TrueVOC® air quality detection, which adheres to global Indoor Air Quality (IAQ) standards. It measures equivalent CO2 (eCO2) from 0 to 65,000 ppb, meeting HVAC requirements, and equivalent Total Volatile Organic Compounds (eTVOC) ranging from 400 to 65,000 ppm CO2-equivalent. Additionally, it supports both the German Federal Environmental Agency’s (UBA) Air Quality Index (AQI-U) from 1 to 5 and a relative Air Quality Index (AQI-S) from 0 to 500. This solution finds applications in IoT devices, wearables, energy-sensitive building automation, HVAC systems, home appliances, and more.

This Click board™ allows for flexible communication options, supporting both I2C and SPI interfaces. These interfaces enable communication speeds up to 1MHz for I2C and 10MHz for SPI. Users can select their preferred communication protocol by adjusting the SMD jumpers in the COMM SEL section. The jumpers must be aligned on the same side to avoid potential issues. An additional SMD jumper, labeled ADDR SEL, enables the adjustment of the I2C slave address.

The ENS161 sensor operates using a 3.3V supply from the mikroBUS™ socket for its logic-level side and uses a 1.8V as a main power supply, which is converted from the 3.3V mikroBUS™ power rail through an AP2112 CMOS LDO regulator. This LDO is enabled via the EN pin from the mikroBUS™ socket, which can also function as a global enable for the entire device. Besides the communication pins for SPI and I2C, the ENS161 also uses an interrupt (INT) pin to alert the host MCU when new output data is available.

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. Also, it 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 Air Quality 11 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	EN	Device Enable
ID SEL	RST	2	RST	INT	15	INT	Interrupt
SPI Select / ID COMM	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

Air Quality 11 Click electrical specifications

Software Support

We provide a library for the Air Quality 11 Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

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

Library Description

This library contains API for Air Quality 11 Click driver.

Key functions

• airquality11_get_aqi_uba This function reads the calculated Air Quality Index according to the UBA.

• airquality11_get_tvoc This function reads the calculated equivalent TVOC concentration in ppb.

• airquality11_get_aqi_s This function reads the calculated relative Air Quality Index proprietary to ScioSense.

Example Description

This example demonstrates the use of the Air Quality 11 Click board by reading and displaying the calculated Air Quality Index according to the UBA and ScioSense, and equivalent TVOC and CO2 concentration.

void application_task ( void ) 
 { 
     uint8_t aqi_uba = 0; 
     uint16_t aq_data = 0; 

     if ( AIRQUALITY11_OK == airquality11_get_aqi_uba( &airquality11, &aqi_uba ) ) 
     { 
         airquality11_display_aqi_uba( aqi_uba ); 
         Delay_ms( 100 ); 
     } 

     if ( AIRQUALITY11_OK == airquality11_get_tvoc( &airquality11, &aq_data ) ) 
     { 
         log_printf( &logger, " TVOC: %u [ppb]rn", aq_data ); 
         Delay_ms( 100 ); 
     } 

     if ( AIRQUALITY11_OK == airquality11_get_co2( &airquality11, &aq_data ) ) 
     { 
         log_printf( &logger, " ECO2: %u [ppm]rn", aq_data ); 
         Delay_ms( 100 ); 
     } 

     if ( AIRQUALITY11_OK == airquality11_get_aqi_s( &airquality11, &aq_data ) ) 
     { 
         log_printf( &logger, " AQIS: %u [idx]rn", aq_data ); 
         Delay_ms( 100 ); 
     } 

     log_printf( &logger, "---------------------------rn " ); 
     Delay_ms( 1000 ); 
 }

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

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.AirQuality11

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 MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE 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.