Beginner
10 min

Create a safe environment by continuously monitoring CO levels with MQ-7 and STM32F031K6

Guardian against the silent enemy

CO Click with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

CO Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Ready to take action against carbon monoxide? Here is the solution.

A

A

Hardware Overview

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 sensor's analog output voltage 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.

CO Click hardware overview image

Features overview

Development board

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Analog Output
PA0
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
NC
NC
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

CO Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Board mapper by product8 hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
STM32 M4 Clicker HA MCU/Select Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Software Support

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.

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief CO Click Example.
 *
 * # Description
 * The demo application shows the reading of the adc 
 * values given by the sensors.
 * 
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Configuring Clicks and log objects.
 *
 * ## Application Task
 * Reads the adc value and prints in two forms (DEC and HEX).
 *
 * @author Jelena Milosavljevic
 *
 */

#include "board.h"
#include "log.h"
#include "co.h"

static co_t co;   /**< CO Click driver object. */
static log_t logger;    /**< Logger object. */

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    co_cfg_t co_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.

    co_cfg_setup( &co_cfg );
    CO_MAP_MIKROBUS( co_cfg, MIKROBUS_1 );
    if ( co_init( &co, &co_cfg ) == ADC_ERROR ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    log_info( &logger, " Application Task " );
    Delay_ms ( 100 );   
}

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 : %u\r\n", 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]\r\n\n", co_an_voltage );
    }

    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

Love this project?

'Buy This Kit' button takes you directly to the shopping cart where you can easily add or remove products.