Intermediate
30 min

Accurate alcohol detection based on the MiCS-5524 and PIC32MZ2048EFH100

Alcohol awareness simplified: Our detection, your safe passage

Alcohol 3 Click with Flip&Click PIC32MZ

Published Aug 29, 2023

Click board™

Alcohol 3 Click

Dev Board

Flip&Click PIC32MZ

Compiler

NECTO Studio

MCU

PIC32MZ2048EFH100

Develop top-of-the-line alcohol breath tester and early fire and gas leakage detection applications easily

A

A

Hardware Overview

How does it work?

Alcohol 3 Click is based on the MiCS-5524 sensor, a compact MOS sensor from SGX Sensortech. This sensor comprises a micromachined metal oxide semiconductor diaphragm with an integrated heating resistor. The resistor produces heat, which catalyzes the reaction, affecting the electrical resistance of the oxide layer itself. The temperature of the heater is quite high: it ranges from 350 °C to 550 °C. After the initial preheating period, the sensor can detect gas changes in intervals below two seconds. The resistance of the MiCS-5524 sensor does not change linearly with the gas concentration, so a proper calibration must be performed before using it for absolute gas concentration measurement applications. The impedance changes the most when used with low gas concentrations. As the atmosphere gets saturated with gas, the impedance changes slowly. This should be considered, especially when

developing applications for estimating blood alcohol content (BAC) from a breath sample (also known as a breathalyzer). The MiCS-5524 sensor is a simple device: it has only four connections. Two pins are the connections of the internal heating element, while the other two are the MOS sensor connections. The application is reduced to calculating a proper resistor for the voltage divider. The datasheet of the MiCS-5524 sensor offers typical values for its resistance when used in clean air (artificial conditions). The sensitivity is then expressed as the ratio between the sensor's resistance in clean air and resistance at a concentration of 60 ppm CO. The middle tap between the sensor (as a resistor) and the fixed resistance provides an output voltage. It depends on the sensor's resistance, allowing it to be used as the input into the MCP3221, a low-power 12-bit A/D converter with an I2C interface, from Microchip.

This ADC allows the output voltage to be translated into digital information, accessed over the I2C pins on the mikroBUS™ socket. By using the power supply voltage as the voltage reference for the conversion, this ADC further reduces the complexity of the design, still offering a good conversion quality, thanks to its low noise input. Due to the sensor's inert nature, this ADC is more than fast enough, although it can provide up to 22.3ksps when operated in the I2C Fast mode. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this 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.

Alcohol 3 Click top side image
Alcohol 3 Click bottom side image

Features overview

Development board

Flip&Click PIC32MZ is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit PIC32MZ microcontroller, the PIC32MZ2048EFH100 from Microchip, four mikroBUS™ sockets for Click board™ connectivity, two USB connectors, LED indicators, buttons, debugger/programmer connectors, and two headers compatible with Arduino-UNO pinout. Thanks to innovative manufacturing technology,

it allows you to build gadgets with unique functionalities and features quickly. Each part of the Flip&Click PIC32MZ development kit contains the components necessary for the most efficient operation of the same board. In addition, there is the possibility of choosing the Flip&Click PIC32MZ programming method, using the chipKIT bootloader (Arduino-style development environment) or our USB HID bootloader using mikroC, mikroBasic, and mikroPascal for PIC32. This kit includes a clean and regulated power supply block through the USB Type-C (USB-C) connector. All communication

methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, user-configurable buttons, and LED indicators. Flip&Click PIC32MZ development kit allows you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Flip&Click PIC32MZ double image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RA2
SCL
I2C Data
RA3
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Alcohol 3 Click Schematic schematic

Step by step

Project assembly

Flip&Click PIC32MZ front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Flip&Click PIC32MZ as your development board.

Flip&Click PIC32MZ front image hardware assembly
Buck 22 Click front image hardware assembly
Prog-cut hardware assembly
Flip&Click PIC32MZ - upright/background 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
Flip&Click PIC32MZ MCU 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

Track your results in real time

Application Output via UART Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for Alcohol 3 Click driver.

Key functions:

  • alcohol3_get_co_in_ppm - This function reads CO (Carbon monoxide) data in ppm (1 ppm - 1000 ppm)

  • alcohol3_get_percentage_bac - This function reads percentage of alcohol in the blood (BAC)

  • alcohol3_get_adc_data - This function reads 12bit ADC value.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * \file 
 * \brief Alcohol3 Click example
 * 
 * # Description
 * Code of this sensor reacts to the presence of deoxidizing and reducing gases,
 * such as ethanol (also known as alcohol).
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Application Init performs Logger and Click initialization.
 * 
 * ## Application Task  
 * Reads percentage of alcohol in the blood (BAC) 
 * and this data logs to USBUART every 1 sec.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "alcohol3.h"

// ------------------------------------------------------------------ VARIABLES

static alcohol3_t alcohol3;
static log_t logger;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    alcohol3_cfg_t cfg;

    /** 
     * 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 ----" );
    Delay_ms ( 100 );

    //  Click initialization.

    alcohol3_cfg_setup( &cfg );
    ALCOHOL3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    alcohol3_init( &alcohol3, &cfg );

    log_printf( &logger, "--------------------------\r\n\n" );
    log_printf( &logger, " ---- Alcohol 3 Click ----\r\n" );
    log_printf( &logger, "--------------------------\r\n\n" );
    Delay_ms ( 1000 );

    log_printf( &logger, " ---- Initialization ---\r\n" );
    log_printf( &logger, "--------------------------\r\n\n" );
    Delay_ms ( 1000 );
}

void application_task ( void )
{
    uint16_t co_ppm;
    uint16_t p_bac;
    float temp_bac;

    //  Task implementation.

    log_printf( &logger, " --- Alcohol diagnostics ---- \r\n" );

    co_ppm = alcohol3_get_co_in_ppm ( &alcohol3 );
    log_printf( &logger, " co in ppm  %d    | \r\n", co_ppm );

    temp_bac = alcohol3_get_percentage_bac( &alcohol3 );
    p_bac = ( uint16_t )( temp_bac * 1000 );

    if ( 10 > p_bac && p_bac < 100 )
    {
        log_printf( &logger, " BAC      | 0.00%d\r\n", p_bac );
    }
    else if ( 100 <= p_bac && 1000 > p_bac )
    {
        log_printf( &logger, " BAC      | 0.0%d\r\n", p_bac );
    }
    else if ( p_bac >= 1000 )
    {
        log_printf( &logger, " BAC      | 0.%d\r\n", p_bac );
    }
    else
    {
        log_printf( &logger, " BAC  | 0.0000\r\n" );
    }
    log_printf( &logger, " ---------------------------- \r\n" );

    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}


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

Additional Support

Resources

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