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1. OBJECTIVE OF THE PROJECT
The objective of this project is to design a robot controlled with a PC, interfaced with sensors to measure the temperature and detect an obstacle in robot’s path.
The project intends to control the robot based on the PC and RF technology. The project uses the Embedded System ultrasonic technology to design this application. The main objective of this project is to read the input from the PC and accordingly control the robot using wireless RF technology.
This project is a device that collects data from the PC, codes the data into a format that can be understood by the controlling section. This system also collects information from the master device and implements commands that are directed by the master.
The objective of the project is to develop a microcontroller based control system. It consists of ultrasonic sensor, microcontroller, robotic arrangement, RF transmitter and RF receiver, RF encoder and decoder.
1.1 BACKGROUND OF THE PROJECT
The software application and the hardware implementation help the microcontroller read the input data from the PC and transmit this data through RF transmitter. The microcontroller at the receiver side allows the RF receiver to receive the transmitted data and control the robot as per the received input. The system is totally designed using embedded systems.
The Controlling unit has an application program to allow the microcontroller read the data from the PC and control the robot. The performance of the design is maintained by controlling unit.
3. OVERVIEW OF THE TECHNOLOGIES USED
3.1 EMBEDDED SYSTEMS:
An embedded system can be defined as a computing device that does a specific focused job. Appliances such as the air-conditioner, VCD player, DVD player, printer, fax machine, mobile phone etc. are examples of embedded systems. Each of these appliances will have a processor and special hardware to meet the specific requirement of the application along with the embedded software that is executed by the processor for meeting that specific requirement.
The embedded software is also called “firm ware”. The desktop/laptop computer is a general purpose computer. You can use it for a variety of applications such as playing games, word processing, accounting, software development and so on.
In contrast, the software in the embedded systems is always fixed listed below:
Embedded systems do a very specific task, they cannot be programmed to do different things. Embedded systems have very limited resources, particularly the memory. Generally, they do not have secondary storage devices such as the CDROM or the floppy disk. Embedded systems have to work against some deadlines. A specific job has to be completed within a specific time. In some embedded systems, called real-time systems, the deadlines are stringent. Missing a deadline may cause a catastrophe-loss of life or damage to property. Embedded systems are constrained for power. As many embedded systems operate through a battery, the power consumption has to be very low.
• Some embedded systems have to operate in extreme environmental conditions such as very high temperatures and humidity.
Following are the advantages of Embedded Systems:
1. They are designed to do a specific task and have real time performance constraints which must be met.
2. They allow the system hardware to be simplified so costs are reduced.
3. They are usually in the form of small computerized parts in larger devices which serve a general purpose.
4. The program instructions for embedded systems run with limited computer hardware resources, little memory and small or even non-existent keyboard or screen.
3.2 RF TECHNOLOGY:
RF refers to radio frequency, the mode of communication for wireless technologies of all kinds, including cordless phones, radar, ham radio, GPS and radio and television broadcasts. RF technology is so much a part of our lives we scarcely notice it for its ubiquity. From baby monitors to cell phones, Bluetooth to remote control toys, RF waves are all around us. RF waves are electromagnetic waves which propagate at the speed of light, or 186,000 miles per second (300,000 km/s). The frequencies of RF waves, however, are slower than those of visible light, making RF waves invisible to the human eye.
The frequency of a wave is determined by its oscillations or cycles per second. One cycle is one hertz (Hz), 1,000 cycles is 1 kilohertz (KHz). A station on the AM dial at 980, for example, broadcasts using a signal that oscillates 980,000 times per second or has a frequency of 980 KHz. A station a little further down the dial at 710 broadcasts using a signal that oscillates 710,000 times a second, or has a frequency of 710 KHz. With a slice of the RF pie licensed to each broadcaster, the RF range can be neatly divided and utilized by multiple parties.
Every device in the United States that uses RF waves must conform to the Federal Communications Commission's (FCC) regulations. A baby monitor, for example, must operate using the designated frequency of 49MHz. Cordless phones and other devices have their own designated frequencies.
The FCC shares responsibility for RF assignment with the National Telecommunications and Information Administration (NTIA), which is responsible for regulating federal uses of the RF spectrum. At present, according to the FCC, frequencies from 9 KHz — 275 GHz have been allocated, with the highest bands reserved for satellite and radio astronomy. The sample chart below lists some of the major categories with approximate RF ranges. In actuality, there are no gaps between categories, as hundreds of other uses are also assigned, from garage door openers and alarm systems to amateur radio and emergency broadcasting.
The RF table is divided and labeled according to frequency, with extremely low frequency (ELF) occupying one end at just 3-30 Hz, and extremely high frequency (EHF) at the other, representing 30-300 GHz. The RF bands most of us are familiar with are VHF (very high frequency), used by radio and television stations 2-13, and UHF (ultra high frequency), used by other television stations, mobile phones and two-way radios. Microwave ovens even use RF waves to cook food, but these waves are in the super high frequency band or SHF. Following the electromagnetic spectrum into even higher frequencies, one finds infrared waves, and finally visible light.
4. HARDWARE IMPLEMENTATION OF THE PROJECT
This chapter briefly explains about the Hardware Implementation of the project. It discusses the design and working of the design with the help of block diagram and circuit diagram and explanation of circuit diagram in detail. It explains the features, timer programming, serial communication, interrupts of AT89S52 microcontroller. It also explains the various modules used in this project.
4.1 PROJECT DESIGN
The implementation of the project design can be divided in two parts.
 Hardware implementation
 Firmware implementation
Hardware implementation deals in drawing the schematic on the plane paper according to the application, testing the schematic design over the breadboard using the various IC’s to find if the design meets the objective, carrying out the PCB layout of the schematic tested on breadboard, finally preparing the board and testing the designed hardware.
The firmware part deals in programming the microcontroller so that it can control the operation of the IC’s used in the implementation. In the present work, we have used the Orcad design software for PCB circuit design, the Keil µv3 software development tool to write and compile the source code, which has been written in the C language. The Proload programmer has been used to write this compile code into the microcontroller. The firmware implementation is explained in the next chapter.
The project design and principle are explained in this chapter using the block diagram and circuit diagram. The block diagram discusses about the required components of the design and working condition is explained using circuit diagram and system wiring diagram.