Alcohol 3 click
PID: MIKROE‐3318
Weight: 23 g
Alcohol 3 click is a gas sensor Click board™, equipped with the MiCS-5524, a
compact metal oxide (MOS) sensor. This sensor reacts to the presence of
deoxidizing and reducing gases, such as ethanol (also known as alcohol). Its
impedance changes as a result of a catalytic reaction, allowing it to be used
in a voltage divider configuration. This voltage can be sampled by an
accurate A/D converter (ADC), allowing data to be read directly over the I2C
interface. The MiCS-5524 sensor itself is a robust sensor, which can be used
in harsh environment for gas leakage detection, in breath checking
applications, early fire detection, etc.
Alcohol 3 click is supported by a mikroSDK compliant library, which includes
functions that simplify software development. This Click board™ comes as a
fully tested product, ready to be used on a system equipped with the
mikroBUS™ socket.
The Click board™ contains the required resistances used to form a voltage
divider with the sensor, as well as the accurate SAR type ADC with 12-bit
resolution which allows the voltage to be converted, using 5V from the
mikroBUS™ rail as a voltage reference. Featuring the MiCS-5524, a robust
and reliable gas sensor which requires a minimal number of additional
components, the MCP3221, an accurate 12-bit ADC by Microchip, proven in
many Click board™ designs so far, Alcohol 3 click represents an ideal
solution for a rapid development of all kinds of breathalyzer applications, gas
leakage applications, fire detection applications, CO detectors, and similar
reducing gasses detecting applications.
How does it work?
Alcohol 3 click is equipped with the MiCS‐5524 sensor, a compact MOS sensor
from SGX Sensortech. This sensor consists of a micromachined metal oxide
semiconductor diaphragm, with an integrated heating resistor. The resistor
produces heat which catalyzes the reaction, which in turn affects the
electrical resistance of the oxide layer itself. The temperature of the heater
is quite high: it is in the range from 350 °C to 550 °C. After the initial
preheating period, the sensor can detect gas changes in time 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 prior to 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 slower. This
should be taken into an account, especially when developing applications for
estimating blood alcohol content (BAC) from a breath sample (also known as
breathalyzers).
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
pins 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 a
clean air (artificial conditions). The sensitivity is then expressed as the ratio
between the resistance of the sensor 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 is
used to provide an output voltage. It directly depends on the resistance of
the sensor, allowing it to be used as the input into the MCP3221, a low-power
12-bit A/D converter with I2C interface, from Microchip. This ADC allows the
output voltage to be translated into a digital information, which can be
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 22.3 ksps when
operated in the I2C Fast mode.
The I2C communication voltage level can be adjusted so that the Click
board™ can be used with both 3.3V and 5V MCUs. The provided SMD jumper
labeled as VCC SEL can be used to select the desired voltage level. However,
the Click board™ requires +5V for a proper operation, regardless of the logic
voltage level selection jumper.
Specifications
Applications
It can be used for various alcohol breath tester
applications, early fire and gas leakage warning
applications, VOC concentration warning applications,
and similar
On-board
modules
MiCS-5524 sensor, a compact MOS sensor from SGX
Sensortech; MCP3221, a low-power 12-bit A/D converter
with I2C interface, from Microchip
Key Features
Robust and reliable MOS sensor, a high-quality 12-bit
ADC from Microchip onboard, can detect a range of
different redux gasses, ideal for a breathalyzer
application development, etc.
Interface
I2C
Input Voltage
3.3V,5V
Click board
size
M (42.9 x 25.4 mm)
Pinout diagram
This table shows how the pinout on Alcohol 3 Click corresponds to the pinout
on the mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC
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
SCL
I2C Clock
NC
6
MOSI
SDA
11
SDA
I2C Data
Power Supply
+3V3
7
3.3V
5V
10
+5V
Power Supply
Ground
GND
8
GND
GND
9
GND
Ground
Onboard settings and indicators
Label
Name
Default
LD1
PWR
-
JP1
VCC SEL
Left
Description
Power LED indicator
Power supply voltage selection
Software support
We provide a library for the Alcohol 3 Click on our LibStock page, as well as a
demo application (example), developed using MikroElektronika compilers. The
demo can run on all the main MikroElektronika development boards.
Library Description
The library initializes and defines the I2C bus driver and drivers that offer a
choice for reads adc data from I2C. The library includes function for reads
CO data in the AIR (in ppm and mg/L), function for reads Ethanol data in
ppm and reads the percentage of alcohol in the blood (BAC).
Key functions:
float alcohol3_getPercentageBAC() - Function for read percentage of alcohol in the blood
uint16_t alcohol3_ethanolInPPM() - Function for read Ethanol (C2H5OH) data in ppm.
uint16_t alcohol3_getCOinPPM() - Function for read CO (Carbon monoxide) data in ppm.
(BAC).
Examples description
The application is composed of the three sections :
System Initialization - Initializes I2C module.
Application Initialization - Initialization driver init.
Application Task - (code snippet) - Reads percentage of alcohol in the blood (BAC) and this
data logs to USBUART every 1 sec.
void applicationTask()
{
uint16_t CO_ppm;
uint16_t pBAC;
char demoText[ 50 ];
mikrobus_logWrite(" ‐‐‐ Alcohol diagnostics ‐‐‐‐", _LOG_LINE);
CO_ppm = alcohol3_getCOinPPM();
WordToStr(CO_ppm, demoText);
mikrobus_logWrite(" CO in ppm | ", _LOG_TEXT);
mikrobus_logWrite(demoText, _LOG_LINE);
pBAC = alcohol3_getPercentageBAC() * 1000;
WordToStr(pBAC, demoText);
if( 10 > pBAC && pBAC = 1000)
{
mikrobus_logWrite(" BAC | 0.", _LOG_TEXT);
LTrim(demoText);
mikrobus_logWrite(demoText, _LOG_LINE);
}
else
{
mikrobus_logWrite(" BAC | 0.0000", _LOG_LINE);
}
mikrobus_logWrite(" ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐", _LOG_LINE);
mikrobus_logWrite( " " , _LOG_LINE);
Delay_ms( 1000 );
}
The full application code, and ready to use projects can be found on
our LibStock page.
Other mikroE Libraries used in the example:
I2C
Conversions
UART
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. The terminal
available in all MikroElektronika compilers, or any other terminal application
of your choice, can be used to read the message.
https://www.mikroe.com/alcohol‐3‐click/2‐13‐19
