Monitor and assess the levels of pollutants with MQ-135 and PIC18F57Q43
Your trusted ally in the pursuit of purer air
Published Feb 13, 2024
Click board™
Air quality Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
By providing real-time monitoring and analysis of air pollutants, this air quality solution aims to protect human health and well-being, reducing the risk of respiratory issues, allergies, and other adverse health effects associated with poor air quality
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Hardware Overview
How does it work?
Air Quality Click is based on the MQ-135, an air quality sensor module for poisonous gases from Zhengzhou Winsen Electronics Technology. The MQ-135 can detect the presence and concentration of toxic gases in the air, such as ammonia gas, sulfide, and benzene steam. It consists of a tin dioxide sensitive layer (SnO2) inside an aluminum oxide AL2O3 ceramic tube (measuring electrodes) alongside a heating element inside its tubular casing. The heater is fixed into a plastic and stainless steel net crust, providing necessary work
conditions for sensitive components. Besides its high sensitivity, the MQ-135 is also characterized by a detection range from 10 to 1000ppm for ammonia gas, toluene, hydrogen, and smoke. The MQ-3 provides an analog representation of polluted concentration in the air sent directly to an analog pin of the mikroBUS™ socket labeled OUT. The analog output voltage the sensor provides varies in proportion to the toxic gas concentration; the higher the toxic gas concentration in the air, the higher the output voltage. Also, this Click board™ has a
built-in potentiometer that allows users to adjust the load resistance of the MQ-135 circuit for optimum performance. 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.
Features overview
Development board
PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive
mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI
GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
48
RAM (Bytes)
8196
You complete me!
Accessories
Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for Air Quality Click driver.
Key functions:
airquality_read_an_pin_value- This function reads results of AD conversion of the AN pinairquality_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 Air quality 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
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "airquality.h"
// ------------------------------------------------------------------ VARIABLES
static airquality_t airquality; /**< Air quality Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
airquality_cfg_t airquality_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.
airquality_cfg_setup( &airquality_cfg );
AIRQUALITY_MAP_MIKROBUS( airquality_cfg, MIKROBUS_1 );
if ( airquality_init( &airquality, &airquality_cfg ) == ADC_ERROR ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void ) {
uint16_t airquality_an_value = 0;
if ( airquality_read_an_pin_value ( &airquality, &airquality_an_value ) != ADC_ERROR ) {
log_printf( &logger, " ADC Value : %u\r\n", airquality_an_value );
}
float airquality_an_voltage = 0;
if ( airquality_read_an_pin_voltage ( &airquality, &airquality_an_voltage ) != ADC_ERROR ) {
log_printf( &logger, " AN Voltage : %.3f[V]\r\n\n", airquality_an_voltage );
}
Delay_ms( 1000 );
}
void main ( void ) {
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
