Develop top-of-the-line alcohol breath tester and early fire and gas leakage detection applications easily
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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.
Features overview
Development board
EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any
circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.
Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
![default](https://dbp-cdn.mikroe.com/catalog/mcus/resources/PIC18F2455.jpg)
Architecture
PIC
MCU Memory (KB)
24
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
2048
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
![Alcohol 3 Click Schematic schematic](https://dbp-cdn.mikroe.com/catalog/click-boards/resources/1ee790a8-3c1e-6b6a-bc22-0242ac120009/schematic.webp)
Step by step
Project assembly
Track your results in real time
Application Output
After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.
![UART Application Output Step 1](https://dbp-cdn.mikroe.com/cms/shared-resources/1eed703a-40a0-6b58-88de-02420a00029a/UART-AO-Step-1.jpg)
Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.
![UART Application Output Step 2](https://dbp-cdn.mikroe.com/cms/shared-resources/1eed703a-eb29-62fa-ba91-02420a00029a/UART-AO-Step-2.jpg)
In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".
![UART Application Output Step 3](https://dbp-cdn.mikroe.com/cms/shared-resources/1eed703b-7543-6fbc-9c69-0242ac120003/UART-AO-Step-3.jpg)
The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.
![UART Application Output Step 4](https://dbp-cdn.mikroe.com/cms/shared-resources/1eed703c-068c-66a4-a4fc-0242ac120003/UART-AO-Step-4.jpg)
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