Website About Engineering Projects For Engineering Students.
Search This Blog
Make Your Own Air Quality Monitoring Device!
Air pollution and concern about air
quality is not something new. Complaints were recorded even in the 13th
century when coal was first used for industrial purposes in London. From
the middle of the 19th century, the atmosphere of major British cities
was regularly polluted by coal smoke in winters, giving rise to the
infamous mixture of fog and smoke known as smog. Today the emphasis has
shifted from pollution problems caused by the industry to the ones
associated with motor vehicle emissions.
Author’s Prototype
Air Quality Index
Air Quality Index, or AQI, is a number used by government agencies
to communicate to the public how polluted the air currently is, or how
polluted it is likely to become. As AQI increases, an increasingly large
percentage of the population experiences severe adverse health effects.
Different countries have their own
air-quality indices corresponding to different national air-quality
standards. Some of these are Air Quality Health Index (Canada), Air
Pollution Index (Malaysia) and Pollutant Standards Index (Singapore).
The national AQI was launched in New
Delhi on September 17, 2014, under Swachh Bharat Abhiyan. There are six
AQI categories (Table I) of the same. The proposed AQI considers eight
pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3 and Pb) for which
short-term (up to 24-hour averaging period) National Ambient Air Quality
Standards are prescribed.
In this project the sensors used are SDS011, MQ-135, DHT11 and DS1307 (as shown in Fig. 1).
A typical PM2.5/10 based meter costs
around US$ 200. Here we present a meter for monitoring air particles,
gas concentration, temperature, humidity and time, which costs around
US$ 45 only. Block diagram of the air-quality meter is shown in Fig. 1.
Fig. 1: Block diagram of the air-quality meter
Circuit and working
Circuit diagram of the air-quality meter
is shown in Fig. 2. Heart of the circuit is ATmega328P (IC3). Other
components used are voltage regulators 7805 (IC1 and IC2), 16×2 LCD
display (LCD1), temperature and humidity module DHT11 (connected to
CON4), gas sensor MQ135 (connected to CON3), PM2.5/PM10 sensor
(connected to CON2) and a few others.
Fig. 2: Circuit diagram of the air-quality meter
ATmega328P.
It can be programmed with embedded software using a standard programmer
or Arduino IDE. ATmega328P offers 23 input/output functional ports, and
a 16MHz crystal oscillator is used to provide timing/clock reference.
Temperature and humidity module (DHT11).
This composite sensor contains a calibrated digital signal output of
temperature and humidity. The sensor (connected to CON4) includes a
resistive-type humidity measurement component and an NTC
temperature-measurement device. Its output pin is connected to pin 12 of
IC3.
Serial real-time clock (RTC) IC (DS1307).
It is a low-power, full binary-coded decimal (BCD) clock/calendar with
56 bytes of NV SRAM. Addresses and data are transferred serially through
an I2C, bi-directional bus. The clock/calendar provides information
about seconds, minutes, hours, days, dates, months and years. SCL and
SDA pins of IC4 are connected toSCL (pin 28) and SDA (pin 27) pins of
IC3, respectively.
Air-quality sensor (MQ135).The
sensitive material of the sensor is tin-dioxide (SnO2), whose
conductivity increases with concentration of gas. Change in conductivity
is converted into output voltage signal, which varies corresponding to
the concentration of the combustible gas. MQ135 is highly sensitive to
ammonia, sulphide and benzene steam, smoke and other harmful gases. It
is a low-cost sensor, suitable for different applications. Output of the
gas sensor (CON3) is connected to analogue input pin 25 of IC3.
PM2.5/PM10 sensor (SDS011).
SDS011 is an air-quality sensor developed by Inovafit, a spin-off from
University of Jinan (Shandong). Because of its size, it is probably one
of the best sensors in terms of accuracy. While other sensors tend to
focus on shrinking the sensor size, SDS011 has opted for a size
tradeoff, allowing it to be used as a larger fan—larger the fan, better
the quality.
SDS011 uses the principle of laser
scattering in the air, which can be obtained from 0.3 microns to 10
microns suspended particulate matter concentration. Data is stable and
reliable, and there is a built-in fan, digital output and a high degree
of integration. UART port of SDS011 (CON2) is connected with IC3 UART
port.
12V power/battery supply (CON1) is
regulated to 5V using IC1 and IC2 and applied to the circuit. When the
system is powered on, the device takes one minute to preheat the gas
sensor before it is ready for operation. LCD1 displays proximate values
of the four sensors connected to IC3. All these parameters are displayed
on LCD1 at an interval of one second.
Software
The software is written in Arduino
programming language. ATmega328P is programmed using Arduino IDE
software. ATmega328P comes with a bootloader that allows to upload a new
code to it without the use of an external hardware programmer. Select
the correct board from ToolsBoard menu in Arduino IDE and burn the
program (sketch) through the standard USB port in the computer.
Various operations are implemented in the code as follows:
RTC library is easy to use and can get the date, time and day of the week accurately.
DHT.temperature and DHT.humidity read temperature and humidity, respectively.
PM_CAL() function calibrates PM2.5/PM10 value.
The arrangement given below gives a
rough approximation of the parts per million (ppm) levels of gas or
pollutants. These values are calculated as:
In this project, we are going to build an RFID Based Access Control System using 8051 Micro Controller . The same system can be named like RFID based door lock or RFID based access management system. If you have been to big hospitals or companies, you might have seen how they used RFID based locks to restrict access to certain areas. In hospitals, only hospital staff with approved RFID tags can access Intensive Care Unit and such restricted areas. So let’s begin to build the system. Project Description A RFID based Door Lock or Access Control System is based on some simple concepts. We store a set of RFID card data in our system, say 3 or 10 RFID card data. When the person with the right RFID card (compatible to data preloaded in our program/system) come and swipes his RFID tag, access will be granted. When the person with the wrong RFID card (whose data is not loaded in our system) swipes his RFID tag, access will be denied. I hope you understand the system concept of RFID based...
In this article, we are going to see how to interface an RTC (Real Time Clock) Module to 8051 micro controller. There are different kinds of RTC module available in the market. We are using the most common RTC module that comes with the DS1307 IC, an LCD module and AT89S52 (8051 variant) for this tutorial. AT89S52 is a typical 8051 microcontroller manufactured by Atmel. Interfacing an RTC module to 8051 microcontroller is pretty simple. You only need to make 2 connections between the RTC module and 8051. So lets get to business! A Real Time Clock module is basically a time tracking device which gives the current time and date. RTC modules that comes with DS3231 IC have the provision to set alarms. Notes On DS1307 RTC Module Here we are using an RTC module with clock chip DS1307 based on I2C protocol (Two Wire Protocol). The module provides details such us second, minute, hour, day of week, day of month, month and year including correction for leap year. It can operate eithe...
We need faster tools and media to prove our ideas, and this is where ready-to use modules like Smart Wi-Fi enter. Fig. 1 shows the top side of Smart Wi-Fi module. Fig. 1: Smart Wi-Fi module Fig. 2: Block diagram of the introduction of Smart Wi-Fi The module is low-cost and versatile; all a developer needs is a USB cable and it is ready to work. For software developers, working with hardware is always a pain, and this is one of the biggest reasons why many ideas never exit a computer. Smart Wi-Fi enables making a product quickly and reliably. With open software resources and hardware data, moving to the final product after the proof of concept is also easy. One of the major aims for writing this article is to show the versatility of this product and show how quick the development can be. In this article a few tests with Smart Wi-Fi are discussed, which show the applicability of this module for development of the Internet of Things (IoT) products. Fig. 3: C...
Comments
Post a Comment