Design of air detector based on AVR microcontroller

1. Project Overview

1.1 Introduction

Healthy life is inseparable from fresh air. We use AVR microcontroller to design an air detector to measure air quality anytime and anywhere.

1.2 Project Background/Motivation for Topic Selection

Air pollution is getting worse and worse. Every citizen should have the right to monitor the pollution of factories and enterprises to protect our environment. We want to design a wireless air detector equipped with gas sensors to detect CO, dust and other components, monitor our pollution sources (of course, it can also be used as an indoor air detector) to make our homes better and better.

2. Demand Analysis

2.1 Functional requirements

Wireless transceiver, analog-to-digital conversion, LCD display, buzzer alarm.

2.2 Performance requirements

The gas detector needs to collect and display data in real time, and the main frequency requirement cannot be low. Considering other unknown factors (such as strong external interference causing multiple transmissions), one display requires 100 clock cycles. For a main frequency of 12M, one display time is no more than milliseconds, so the real-time performance can be met. In addition, our model only has 2 to 4 data inputs, and 512 bytes of memory is sufficient. Peripherals require LCD, LED, keyboard, wireless transceiver module, serial port and other external devices.

3. Solution Design

3.1 System function implementation principle (in addition to pictures, text description is required)

Use a small remote-controlled helicopter equipped with a gas detector to detect gas and send it back to the microcontroller for processing. The gas content value can be displayed by pressing a button. If a certain gas exceeds the standard, the corresponding LED light will light up and the buzzer will sound.

3.2 Hardware platform selection and resource allocation

The gas sensor (2~4) collects the content of external polluted gas in time-sharing, converts A/D and transmits it to the AVR microcontroller for processing in time-sharing, then transmits it through the wireless transmitting module, is received by the wireless receiving module, and is sent to another AVR microcontroller for processing and displaying the gas content. If the gas content exceeds the standard, the buzzer sounds and the corresponding light-emitting diode flashes.

3.3 System Software Architecture

3.4 System software flow (text description is required in addition to pictures)

As shown in the figure above, the program starts to initialize, and the microcontroller mounted on the remote-controlled helicopter starts to collect data in time-sharing, then AD conversion, and time-sharing transmission to the AVR microcontroller for processing and storage. After encoding, it is sent to another microcontroller for error checking. If an error occurs, a retransmission signal is sent and retransmitted again. If no error occurs, a confirmation signal is sent, the sending register is cleared, and new data is loaded again, waiting to be sent.

After receiving, it is sent to the AVR microcontroller for processing and then to the LCD display for display. If a gas exceeds the standard, the LED light corresponding to the gas will light up and the buzzer will sound.

3.5 Expected Results of the System

It can detect polluted gases with a wide detection range. It can not only detect the pollution situation of the external environment, but also detect the indoor gas conditions to avoid accidents such as gas poisoning.

The gas detector device can perform gas measurement in real time and can pause or refresh displayed data as needed.