CO Click

How does it work?

CO Click is based on the MQ-7, a carbon monoxide sensor from Zhengzhou Winsen Electronics Technology, which detects carbon monoxide’s presence and concentration in the air. The gas sensing layer on the MQ-7 sensor unit is made of Tin dioxide (SnO2), which has lower conductivity in clean air. The conductivity increases as the levels of carbon monoxide rise. It has a high sensitivity to carbon monoxide in a wide range suitable for detecting carbon monoxide in concentrations from 20 to 2000ppm.

Besides a binary indication of the presence of carbon monoxide, the MQ-7 also provides an analog representation of its concentration in the air sent directly to an analog pin of the mikroBUS™ socket labeled OUT. The analog output voltage provided by the sensor varies in proportion to the carbon monoxide concentration; the higher the carbon monoxide concentration in the air, the higher the output voltage. Also, the MQ-7 has a built-in potentiometer that allows you to adjust the Load Resistance of the sensor circuit.

This Click board™ can be operated only with a 5V 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 CO Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog Signal	OUT	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	NC
	NC	6	MOSI	SDA	11	NC
	NC	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

CO Click electrical specifications

Software Support

We provide a library for the CO 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 CO Click driver.

Key functions

• co_read_an_pin_value This function reads results of AD conversion of the AN pin.

• co_read_an_pin_voltage This function reads results of AD conversion of the AN pin and converts them to proportional voltage level.

Example Description

The demo application shows the reading of the adc values given by the sensors.

 void application_task ( void ) { 
     uint16_t co_an_value = 0; 

     if ( co_read_an_pin_value ( &co, &co_an_value ) != ADC_ERROR ) { 
         log_printf( &logger, " ADC Value : %urn", co_an_value ); 
     } 

     float co_an_voltage = 0; 

     if ( co_read_an_pin_voltage ( &co, &co_an_voltage ) != ADC_ERROR ) { 
         log_printf( &logger, " AN Voltage : %.3f[V]rnn", co_an_voltage ); 
     } 

     Delay_ms( 1000 ); 
 }

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.CO

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.