Doc Ment Naga

AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM

CHAPTER 1

INTRODUCTION

Embedded systems are electronic devices that incorporate microprocessor with in their

implementation. The main purpose of the microprocessor is to simplify the system design and

provide flexibility. This system may not have a disk driver and so the software is often stored in a

ROM chip. Embedded systems often have several things to do at once. They must respond to

external events (e.g.: someone pushes an elevator button).

An Embedded system is any computer system hidden inside a product other than a

computer. Embedded systems are found in wide range of applications like expensive industrial

control applications. As the technology brought down the cost of dedicated processors. They

began to appear in moderately expansive applications such as automobiles, communications and

office equipment, televisions. Today’s embedded system is so inexpensive that they are used in

almost every electronic product in our life.

Many embedded systems have to run 24 hours a day you can’t just “reboot” when

something goes wrong. For this reason a good coding practices and thorough testing take on a

new level of realm of embedded processors.Performance goals will force us to learn and apply

new techniques such as multitasking and scheduling. The need to communicate directly with

sensors actuators, keypads, displays etc will require programmers to have a better understanding

of how alternative methods for performing input and output provide opportunities to trade speed,

complexity and cost.

How powerful are embedded processors

The embedded system found in most consumer products employs a single chip controller.

That includes the microprocessor, a limited amount of memory and simple input output devices.

By far the vast majority of the embedded systems in production today are based on the 4bit, 8bit,

or 16bit processors. Although 32bit processors account for relatively small percentage of the

current market, their use in embedded systems is growing at the fastest rate. In 1998, almost 250

million 32bit embedded processor were shipped, compared to 100million desk top computers.

SPHOORTHY ENGINEERING COLLEGE 1


what programming languages are used

Although it is occasionally necessary to code some small parts of an embedded

application program in assembly language, rest of the code in even the simplest application is

written in a high level language. Traditionally the choice of the language has been ‘C’. Programs

written in ‘C’ are very portable from one compiler and/or target processor to another. C

compilers are available for a number of different target processors, and they generate very

efficient code.

Despite the popularity of C++ and Java for desktop application programming, they are

rarely used in embedded systems because of the large run-time overhead required to support

some of their features. For example, even a relatively simple C++ program will produce about

twice as much code as the same program written in C,and the situation is Much worse for large

program that makes extensive use of the run-time library.

Ec++ was designed by a group of Japanese microprocessor manufacturers called the EC++

technical group.

Embedded Application Program

Fig. Embedded Application Program


Image

File

Compiler

Assembler

Linker

loader

Read write Memory (RAM)

(RAM)

Read only Memory (ROM)

(ROM)

Rom “burner”

“Burner”

file

Program initialization

Re entrant library

Run time kernel

Object Files


A compiler and/or an assembler are used to build one or more object files that are linked to

gather with a run-time library to form an executable image that’s stored as a file on the disk.

When we want run a desktop application program, its executable image is loaded from a disk

into memory by a part of the operating system known as the “Loader”. The operating system

itself is already in memory, put there during the boot process. The desktop system is intended to

run a number of different application programs. Thus, read-write main memory is used so that an

entirely different application program can be quickly and easily loaded into memory, replacing

the previous application whenever necessary.

Unlike general desktop systems embedded systems are designed to serve a single purpose.

Once the embedded software is in memory, there is usually no reason to change it. This allows a

less expansive read only memory to be used for permanent storage of the program. Since there is

no need to store the program on disk, a significant amount of software can be eliminated that

would otherwise be necessary to support a file system.

Both the embedded applications software and a real-time kernel are stored in the same

read only memory as a single program image, with no need for a file system, the kernel Is much

smaller than the regular OS and is easily linked into the program as yet together another object

file. In general the same kind of software development tools are used to build both embedded

and desktop applications. Although tools suites designed especially for embedded applications

developments are commercially available, in many cases it’s possible to use same compiler,

assembler and linker that you use for desktop applications. There are two important differences,

however. First, the run time library that comes with compilers for desktop applications is usually

not intended for multitasking applications and must be replaced by one that is reentrant.

Second, additional software called a locator is required to convert the linkers output to a

form suitable for storing in read only memory. In a desktop OS load an executable program

image produced by a linker into memory, it has to modify a few bytes whose value depends on

the address where the program is to be loaded. Before we can use such an executable image to

permanently store our embedded program in a read only memory, we must first perform the same

“fix-ups” using a program called a locator.



1.1 Embedded Software Development Tools

Application programmers typically do their work on the same kind of computer on which

the application will run. If programmers edit the program, compiles its links it, tries it out and

debugs it, all on the same machine. The tactic has to change for embedded systems. In the first

place, most embedded systems have specialized hardware to attach to special sensors or to drive

special controls, and the only way to try out the software is on the specialized hardware. In the

second place, embedded systems often use microprocessors that have never been used as the

basis of workstations. Obviously, programs do not get magically compiled into the instruction set

for whatever microprocessor you happen to have chosen for your system, and programs do not

magically jump into the memory of your embedded system for execution.

Host and Target Machines

Most programming work for embedded systems is done on a host, a computer system on

which all the programming tools run. Only after the program has been written, compiled,

assembled and linked is it moved to target, the system that is shipped to customers. Some people

use the word workstation instead of host; the word target is almost universal (See in Figure given

below).

HOST MACHINE

Cross Assemblers

Another tool that will need if we must write any of the program in assembly language is a

cross assembler. As we might imagine from the name, a cross assembler is an assembler that run

on host but produces binary instructions appropriated for the target. The input to the cross

assembler must be assembly language appropriated for the target (since that is the only assembly

language that can be translated into binary instructions for the target).

Linker/Locators for Embedded Software

The first difference between a native linker and locator is the nature of the output files that

they create. The native linker creates a file on the disk drive of the host system that is read by



the O.S called the loader. The locator creates file that will be used by some program that copies

the output to the target system. Later, the output from the locator will have to run its own. In an

embedded system, there is no separate O.S. Linkers for embedded system is often called as

locators.

Fig. 1.1 Cross Compilers


EC Files(.C)

Cross Compiler

.Obj

Assembly (.asm)

Cross Assembler

.Obj

Linker

Locator


1.2 Embedded Design Methodology

The fast growing complexity and short time to market of today's real-time embedded

systems necessitates new design methods and tools to face the problem of specification, design,

analysis, scheduling, simulation, integration and validation of complex systems. In the project, a

system level method for embedded real-time systems design is developed exploiting System

strength for system level Dan co-design modeling. In order to support the methodology, some

extension to System is proposed starting form RTOS modeling and framework for scheduling

simulation.


http://www.systemc.org/


1.3 Schematic Diagram:



Fig:1.2.1 Schematic diagram



CHAPTER 2

EMBEDDED MICROCONTROLLER AND HARDWARE

2.1 Introduction

A micro controller (also MCU or µC) is a functional computer system-on-a-chip. It

contains a processor core, memory, and programmable input/output peripherals.

Micro controllers include an integrated CPU, memory (a small amount of RAM, program

memory, or both) and peripherals capable of input and output. It emphasizes high integration, in

contrast to a microprocessor, which only contains a CPU (the kind used in a PC). In addition to

the usual arithmetic and logic elements of a general-purpose microprocessor, the micro controller

integrates additional elements such as read-write memory for data storage, read-only memory for

program storage, Flash memory for permanent data storage, peripherals, and input/output

interfaces.

At clock speeds of as little as 32KHz, micro controllers often operate at very low speed

compared to microprocessors, but this is adequate for typical applications. They consume

relatively little power (mill watts or even microwatts), and will generally have the ability to retain

functionality while waiting for an event such as a button press or interrupt. Power consumption

while sleeping (CPU clock and peripherals disabled) may be just nanowatts, making them ideal

for low power and long lasting battery applications.

Micro controllers are used in automatically controlled products and devices, such as

automobile engine control systems, remote controls, office machines, appliances, power tools,

and toys. By reducing the size, cost, and power consumption compared to a design using a

separate microprocessor, memory, and input/output devices, micro controllers make it

economical to electronically control many more processes.

Circumstances that we find ourselves in today in the field of microcontrollers had their

beginnings in the development of technology of integrated circuits. This development has made it

possible to store hundreds of thousands of transistors into one chip. Microprocessors and

microcontrollers are widely used in embedded systems products. Microcontroller is a

programmable device.


http://en.wikipedia.org/wiki/Read-only_memory

http://en.wikipedia.org/wiki/Read-write

http://en.wikipedia.org/wiki/Personal_computer

http://en.wikipedia.org/wiki/Microprocessor

http://en.wikipedia.org/wiki/Input/output

http://en.wikipedia.org/wiki/Integrated_circuit

http://en.wikipedia.org/wiki/System-on-a-chip

http://en.wikipedia.org/wiki/Computer


2.2 The Major Features of 89C52 Microcontroller

Fig:2.2 block diagram of 89C52

Why AT 89C52


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM The system requirements and control specifications clearly rule out the use of 16, 32 or 64 bit

micro controllers or microprocessors. Systems using these may be earlier to implement due to

large number of internal features. They are also faster and more reliable but, the above

application is satisfactorily served by 8-bit micro controller. Moreover ATMEL is the leader in

flash technology in today’s market place Using an inexpensive 8-bit Microcontroller will doom

the 32-bit product failure in any competitive market place.Coming to the question of why to use

AT89C52 of all the 8-bit microcontroller available in the market the main answer would be

because it has 8 Kb on chip flash memory which is just sufficient for our application. The on-chip

Flash ROM allows the program memory to be reprogrammed in system or by conventional non-

volatile memory Programmer. Moreover ATMEL is the leader in flash technology in today’s

market place and hence using AT 89C52 is the optimal solution. Holding low forces the CPU to

execute out of external memory regardless of the Program .AT89C52 consists of Internal ROM

or EPROM (8751) of 0(8031) to 8K (89C52)Internal RAM of 256 bytes. Eight –bit CPU with

registers A (the accumulator) and B Sixteen-bit program counter (PC) and data pointer (DPTR).

PSEN: Program Store Enable is the read strobe to external Program Memory. When the device

is executing out of external Program Memory, PSEN is activated twice each machine cycle

(except that two PSEN activations are skipped during accesses to external Data Memory). PSEN

is not activated when the device is executing out of internal Program Memory. Another

important signal 89C52 is program store signal.

EA/VPP: When EA is held high the CPU executes out of internal Program Memory (unless the

Program Counter exceeds 0FFFH in the 80C52). Holding EA low forces the CPU to execute out

of external memory regardless of the Program Counter value. In the 80C31, EA must be

externally wired low. In the EPROM devices, this pin also receives the programming supply

voltage (VPP) during EPROM programming. The EA pin is connected to vcc to indicate that the

program code is stored in the micro controller on chip ROM. To indicate the program code is

stored in external ROM.



2.3 PIN DIAGRAM OF AT 89C52


1234567891011121314151617181920

4039383736353433323130292827262524232221

P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7RST

(RXD)P3.0(TXD)P3.1

(T0)P3.4(T1)P3.5

XTAL2XTAL1

GND

(INT0)P3.2(INT1)P3.3

(RD)P3.7(WR)P3.6

VccP0.0(AD0)P0.1(AD1)P0.2(AD22222)P0.3(AD3)P0.4(AD4)P0.5(AD5)P0.6(AD6)P0.7(AD7)EA/VPPALE/PROGPSENP2.7(A15)P2.6(A14)P2.5(A13)P2.4(A12)P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)

AT89 C52


2.3 Port Description

ALE/PROG: Address Latch Enable output pulse for latching the low byte of the address

during accesses to external memory. ALE is emitted at a constant rate of 1/6 of the oscillator

frequency, for external timing or clocking purposes, even when there are no accesses to external

memory. (However, one ALE pulse is skipped during each access to external Data Memory.)

This pin is also the program pulse input (PROG) during EPROM programming.

XTAL1: Input to the inverting oscillator amplifier.

XTAL2: Output from the inverting oscillator amplifier.

Port 0: Port 0 is an 8-bit open drain bi-directional port. As an open drain output port, it can sink

eight LS TTL loads. Port 0 pins that have 1s written to them float, and in that state will function

as high impedance inputs. Port 0 is also the multiplexed low-order address and data bus during

accesses to external memory. In this application it uses strong internal pull-ups when emitting 1s.

Port 0 emits code bytes during program verification. In this application, external pull-ups are

required.



Port 1: Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. Port 1 pins that have 1s

written to them are pulled high by the internal pull-ups, and in that state can be used as inputs. As

inputs, port 1 pins that are externally being pulled low will source current because of the internal

pull-ups.

Port 2: Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 emits the high-

order address byte during accesses to external memory that use 16-bit addresses. In this

application, it uses the strong internal pull-ups when emitting 1s.

Port 3: Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. It also serves the

functions of various special features of the 80C52 Family as follows:

Port Pin Alternate Function




PORT 3.0 RXD ( SERIAL INPUT

PORT)

PORT 3.1 TXD (SERIAL OUTPUT

PORT)

PORT 3.2 INTO ( EXTERNAL

INTERRUPT 0)

PORT 3.3 INT1 ( EXTERNAL

INTERRUPT 1)

PORT 3.4 T0 (TIMER 0 EXTERNAL

INPUT)

PORT 3.5 T1 (TIMER 1 EXTERNAL

INPUT)

PORT 3.6 WR (EXTERNAL DATA

MEMORY WRITE

STROBE)

PORT 3.7 RD (EXTERNAL DATA

MEMORY READ

STROBE)

VCC SUPPLY VOLTAGE

VSS CIRCUIT GROUND

POTENTIAL


AT89C52 MICROCONTROLLER ARCHITECTURE

The 89C52 architecture consists of these specific features:

Eight –bit CPU with registers A (the accumulator) and B

Sixteen-bit program counter (PC) and data pointer (DPTR)

Eight- bit stack pointer (PSW)

Eight-bit stack pointer (Sp)

Internal ROM or EPROM (8751) of 0(8031) to 8K (89C52)

Internal RAM of 256 bytes:

1. Four register banks, each containing eight registers

2. Sixteen bytes, which may be addressed at the bit level

3. Eighty bytes of general- purpose data memory

Thirty –two input/output pins arranged as four 8-bit ports:p0-p3

Two 16-bit timer/counters: T0, T1 and T2

Full duplex serial data receiver/transmitter: SBUF

Control registers: TCON, TMOD, SCON, PCON, IP, and IE

Two external and three internal interrupts sources.

Oscillator and clock circuits

AT89C52 FAMILY INSTRUCTION SET

The 89C52 instruction set is optimized for 8-bit control applications. It provides a variety

of fast addressing modes for accessing the internal RAM to facilitate byte operations on small

data structures. The instruction set provides extensive support for one-bit variables as a separate

data type, allowing direct bit manipulation in control and logic systems that require Boolean

processing.



2.4 Basic Components of Embedded System

Embedded Hardware, Embedded Software/Firmware, RTOS or Real Time Kernel

Fig. 2.3 Basic Embedded Components

2.5 Addressing Modes

The addressing modes in the 89C52 instruction set are as follows:

a. Direct Addressing

In direct addressing the operand is specified by an 8-bit address field in the instruction.

Only internal Data RAM and SFRs can be directly addressed.

b. Indirect Addressing SPHOORTHY ENGINEERING COLLEGE 17

[Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Text Box Tools tab to change the formatting of the pull quote text box.]

UART

I/O Ports

I2C

CPU

Interrupts

Timers

ROM S/WRAMElec

tric

al in

terf

ace

Har

d w

are

LCD

DAC

ADC

Input drivers interface

Output driver interfaceKeypad

interface

Switches/Sensors Application specific

Hard ware

AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMIn indirect addressing the instruction specifies a register which contains the address of the

operand. Both internal and external RAM can be indirectly addressed. The address register for 8-

bit addresses can be R0 or R1 of the selected bank, or the Stack Pointer. The address register for

16-bit addresses can only be the 16-bit “data pointer” register, DPTR.

c. Register Instructions

The register banks, containing registers R0 through R7, can be accessed by certain

instructions which carry a 3-bit register specification within the opcode of the instruction.

Instructions that access the registers this way are code efficient, since this mode eliminates an

address byte. When the instruction is executed, one of the eight registers in the selected bank is

accessed. One of four banks is selected at execution time by the two bank select bits in the PSW.

d. Register-Specific Instructions

Some instructions are specific to a certain register. For example, some instructions always

operate on the Accumulator, or Data Pointer, etc., so no address byte is needed to point to it. The

op-code itself does that. Instructions that refer to the Accumulator as A assemble as accumulator

specific op-codes.

e.Immediate Constants

The value of a constant can follow the op-code in Program Memory. For example, MOV

A, #100 loads the Accumulator with the decimal number 100. The same number could be

specified in hex digits as 64H.

f. Indexed Addressing

Only program Memory can be accessed with indexed addressing, and it can only be read.

This addressing mode is intended for reading look-up tables in Program Memory A 16-bit base

register (either DPTR or the Program Counter) points to the base of the table, and the

Accumulator is set up with the table entry number. The address of the table entry in Program

Memory is formed by adding the Accumulator data to the base pointer. Another type of indexed

addressing is used in the “case jump” instruction. In this case the destination address of a jump

instruction is computed as the sum of the base pointer and the Accumulator data.



2.6 MEMORY MODELS

MEMORY ORGANIZATION

All 80C51 devices have separate address spaces for program and data memory, as shown in

Figures 1 and 2. The logical separation of program and data memory allows the data memory to

be accessed by 8-bit addresses, which can be quickly stored and manipulated by an 8-bit CPU.

Nevertheless, 16-bit data memory addresses can also be generated through the DPTR register.

Program memory (ROM, EPROM) can only be read, not written. There can be up to 64k bytes of

program memory. In the 80C51, the lowest 4k bytes of program are on-chip. In the ROM less

versions, all program memory is external.

The read strobe for external program memory is the PSEN (program store enable). Data

Memory (RAM) occupies a separate address space from Program Memory. In the 80C52, the

lowest 128 bytes of data memory are on-chip. Up to 64k bytes of external RAM can be addressed

in the external Data Memory space. In the ROM less version, the lowest 128 bytes are on-chip.

The CPU generates read and write signals, RD and WR, as needed during external Data Memory

accesses. External Program Memory and external Data Memory may be combined if desired by

applying the RD and PSEN signals to the inputs of an AND gate and using the output of the gate

as the read strobe to the external Program/Data memory.

a. Program Memory

After reset, the CPU begins execution from location 0000H. Each interrupt is assigned a

fixed location in Program Memory. The interrupt causes the CPU to jump to that location, where

it commences execution of the service routine. External Interrupt 0, for example, is assigned to

location 0003H.

If External Interrupt 0 is going to be used, its service routine must begin at location 0003H.

If the interrupt is not going to be used, its service location is available as general purpose

Program Memory.

The interrupt service locations are spaced at 8-byte intervals: 0003Hfor External Interrupt

0, 000BH for Timer 0, 0013H for External Interrupt 1, 001BH for Timer 1, etc. If an interrupt

service routine is short enough (as is often the case in control applications), it can reside entirely


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMwithin that 8-byte interval. Longer service routines Can use a jump instruction to skip over

subsequent interrupt locations, if other interrupts are in use. The lowest 4k bytes of Program

Memory can either be in the on-chip ROM or in an external ROM. This selection is made by

strapping the EA (External Access) pin to either VCC, or VSS. In the 80C51, if the EA pin is

strapped to VCC, then the program fetches to addresses 0000H through 0FFFH are directed to the

internal ROM. Program fetches to addresses 1000H through FFFFH are directed to external

ROM. If the EA pin is strapped to VSS, then all program fetches are directed to external ROM.

The ROM less parts (8031, 80C31, etc.) must have this pin externally strapped to VSS to enable

them to execute from external Program Memory. The read strobe to external ROM, PSEN, is

used for all external program fetches. PSEN is not activated for internal program fetches.

The hardware configuration for external program execution is shown in Figure 4. Note that

16 I/O lines (Ports 0 and 2) are dedicated to bus functions during external Program Memory

fetches. Port 0 (P0 in Figure 4) serves as a multiplexed address/data bus. It emits the low byte of

the Program Counter (PCL) as an address, and then goes into a float state awaiting the arrival of

the code byte from the Program Memory. During the time that the low byte of the Program

Counter is valid on Port 0, the signal ALE (Address Latch Enable) clocks this byte into an

address latch. Meanwhile, Port 2 (P2 in Figure 4) emits the high byte of the Program Counter

(PCH). Then PSEN strobes the EPROM and the code byte is read into the microcontroller.

Program Memory addresses are always 16 bits wide, even though the actual amount of

Program Memory used may be less than 64k bytes. External program execution sacrifices two of

the 8-bit ports, P0 and P2, to the function of addressing the Program Memory.

b.Data Memory

The CPU in this case is executing from internal ROM. Port 0 serves as a multiplexed

address/data bus to the RAM, and 3 lines of Port 2 are being used to page the RAM. The CPU

generates RD and WR signals as needed during external RAM accesses. There can be up to 64k

bytes of external Data Memory. External Data Memory addresses can be either 1 or 2 bytes wide.

One-byte addresses are often used in conjunction with one or more other I/O lines to page the

RAM, as shown in Figure 5. Two-byte addresses can also be used, in which case the high address

byte is emitted at Port 2. Internal Data Memory is mapped in Figure 6.


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMThe memory space is shown divided into three blocks, which are generally referred to

as the Lower 128, the Upper 128, and SFR space. Internal Data Memory addresses are always

one byte wide, which implies an address space of only 256 bytes. However, the addressing modes

for internal RAM can in fact accommodate 384 bytes, using a simple trick. Direct addresses

higher than 7FH access one memory space and indirect addresses higher than 7FH access a

different memory space. Thus Figure 6 shows the Upper 128 and SFR space occupying the same

block of addresses, 80H through FFH, although they are physically separate entities.

The Lower128 bytes of RAM are present in all 80C51 devices as mapped in Figure 7. The

lowest 32 bytes are grouped into 4 banks of 8 registers. Program instructions call out these

registers as R0 through R7. Two bits in the Program Status Word (PSW) select which register

bank is in use. This allows more efficient use of code space, since register instructions are shorter

than instructions that use direct addressing. The next 16 bytes above the register banks form a

block of bit-addressable memory space.

The 80C51 instruction set includes a wide selection of single-bit instructions, and the 128

bits in this area can be directly addressed by these instructions. The bit addresses in this area are

00H through 7FH. All of the bytes in the Lower 128 can be accessed by either direct or indirect

addressing. The Upper 128 (Figure 8) can only be accessed by indirect addressing. Figure 9 gives

a brief look at the Special Function Register (SFR) space. SFRs include the Port latches, timers,

peripheral controls, etc. These registers can only be accessed by direct addressing. Sixteen

addresses in SFR space are both byte- and bit-addressable. The bit-addressable SFRs are those

whose address ends in 0H or 8H

Fig 2.7 80C51 Block Diagram



.



Types of memory:

The 89C52 have three general types of memory. They are on-chip memory , external

Code memory and external Ram. On-Chip memory refers to physically existing memory on

the microcontroller itself. External code memory is the code memory that resides off chip. This

is often in the form of an external EPROM. External RAM is the Ram that resides off chip. This

often is in the form of standard static RAM or flash RAM.

a) Code memory

Code memory is the memory that holds the actual 89C52 programs that is to be run.

This memory is limited to 64K. Code memory may be found on-chip or off-chip. On-Chip

memory refers to physically existing memory on the microcontroller itself. External code

memory is the code memory that resides off chip It is possible to have 4K of code memory on-

chip and 60K off chip memory simultaneously. If only off-chip memory is available then there

can be 64K of off chip ROM. This is controlled by pin provided as EA

b)Internal RAM

The 89C52 have a bank of 256 of internal RAM. The internal RAM is found on-chip.

So it is the fastest Ram available. And also it is most flexible in terms of reading and writing.

Internal Ram is volatile, so when 89C52 is reset, this memory is cleared. 256 bytes of internal

memory are subdivided. The CPU in this case is executing from internal ROM. Port 0 serves as a

multiplexed address/data bus to the RAM, and 3 lines of Port 2 are being used to page the RAM.

The CPU in this case is executing from internal ROM. Port 0 serves as a multiplexed address/data

bus to the RAM, and 3 lines of Port 2 are being used to page the RAM. the addressing modes for

internal RAM can in fact accommodate 384 bytes.

The first 32 bytes are divided into 4 register banks. Each bank contains 8 registers. Internal RAM

also contains 256 bits, which are addressed from 20h to 2Fh. These bits are bit addressed i.e. each

individual bit of a byte can be addressed by the user. They are numbered 00h to 7Fh. The user

may make use of these variables with commands such as SETB and CLR.

CHAPTER 3 SPHOORTHY ENGINEERING COLLEGE 23


HARDWARE DESCRIPTION

3.1 REGULATED POWER SUPPLY

A variable regulated power supply, also called a variable bench power supply, is one where

you can continuously adjust the output voltage to your requirements. Varying the output of the

power supply is the recommended way to test a project after having double checked parts

placement against circuit drawings and the parts placement guide. This type of regulation is ideal

for having a simple variable bench power supply. Actually this is quite important because one of

the first projects a hobbyist should undertake is the construction of a variable regulated power

supply. While a dedicated supply is quite handy e.g. 5V or 12V, it's much handier to have a

variable supply on hand, especially for testing. Most digital logic circuits and processors need a 5

volt power supply. To use these parts we need to build a regulated 5 volt source. Usually you

start with an unregulated power supply ranging from 9 volts to 24 volts DC (A 12 volt power

supply is included with the Beginner Kit and the Microcontroller Beginner Kit.). To make a 5

volt power supply, we use a LM7805 voltage regulator IC .

FIG:

The LM7805 is simple to use. You simply connect the positive lead of your unregulated DC

power supply (anything from 9VDC to 24VDC) to the Input pin, connect the negative lead to the

Common pin and then when you turn on the power, you get a 5 volt supply from the Output pin.

a. CIRCUIT FEATURES


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM Brief description of operation: Gives out well regulated +5V output, output current capability

of 100 mA

Circuit protection: Built-in overheating protection shuts down output when regulator IC

gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit successfully as

part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unregulated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input transformer cost

b. BLOCK DIAGRAM

Fig 3.1 Power Supply Block Diagram

c. CIRCUIT DIAGRAM



3.2 CIRCUIT DIAGRAM OF POWER SUPPLY

BASIC POWER SUPPLY CIRCUIT

Above is the circuit of a basic unregulated dc power supply. A bridge rectifier D1 to D4

rectifies the ac from the transformer secondary, which may also be a block rectifier such as WO4

or even four individual diodes such as 1N4004 types. (See later re rectifier ratings).The principal

advantage of a bridge rectifier is you do not need a centre tap on the secondary of the

transformer. A further but significant advantage is that the ripple frequency at the output is twice

the line frequency (i.e. 50 Hz or 60 Hz) and makes filtering somewhat easier.

As a design example consider we wanted a small unregulated bench supply for our

projects. Here we will go for a voltage of about 12 - 13V at a maximum

output current (IL) of 500ma (0.5A). Maximum ripple will be 2.5% and load regulation is

5%.Now the RMS secondary voltage (primary is whatever is consistent with your area) for our

power transformer T1 must be our desired output Vo PLUS the voltage drops across D2 and D4 (

2 * 0.7V) divided by 1.414.

This means that Vsec = [13V + 1.4V] / 1.414 which equals about 10.2V. Depending on the

VA rating of your transformer, the secondary voltage will vary considerably in accordance with

the applied load. The secondary voltage on a transformer advertised as say 20VA will be much

greater if the secondary is only lightly loaded. If we accept the 2.5% ripple as adequate for our

purposes then at 13V this becomes 13 * 0.025 = 0.325 Vrms. The peak to peak value is 2.828

time this value. Vrip = 0.325V X 2.828 = 0.92 V and this value is required to calculate the value

of C1.


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMAlso required for this calculation is the time interval for charging pulses. If you are on a

60Hz system it is 1/ (2 * 60 ) = 0.008333 which is 8.33 milliseconds. For a 50Hz system it is 0.01

sec or 10 milliseconds.Remember the tolerance of the type of capacitor used here is very loose.

The important thing to be aware of is the voltage rating should be at least 13V X 1.414 or 18.33.

Here you would use at least the standard 25V or higher (absolutely not 16V).With our rectifier

diodes or bridge they should have a PIV rating of 2.828 times the Vsec or at least 29V. Don't

search for this rating because it doesn't exist. Use the next highest standard or even higher. The

current rating should be at least twice the load current maximum i.e. 2 X 0.5A or 1A. A good

type to use would be 1N4004, 1N4006 or 1N4008 types.

These are rated 1 Amp at 400PIV, 600PIV and 1000PIV respectively. Always be on the

lookout for the higher voltage ones when they are on special.

TRANSFORMER RATING –

In our example above we were taking 0.5A out of the Vsec of 10V. The VA required is 10 X

0.5A = 5VA. This is a small PCB mount transformer available in Australia and probably

elsewhere. This would be an absolute minimum and if you anticipated drawing the maximum

current all the time then go to a higher VA rating.The two capacitors in the primary side are small

value types and if you don't know precisely and I mean precisely what you are doing then OMIT

them

CONSTRUCTION

The whole project MUST be enclosed in a suitable box. The main switch (preferably

double pole) must be rated at 240V or 120V at the current rating. All exposed parts within the

box MUST be fully insulated, preferably with heat shrink tubing.

3.2BUZZER

A buzzer is an audio signaling device which may be mechanical, electromechanical,

or piezoelectric. Typical uses of buzzers and beepers include alarms, timers and confirmation of

user input such as a mouse click or keystroke.A joy buzzer is an example of a purely mechanical

buzzer. Early devices were based on an electromechanical system identical to an electric

bell without the metal gong.

Similarly, a relay may be connected to interrupt its own actuating current, causing

the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a sounding



board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made. A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep.

Uses

Enunciator panels

Electronic metronomes

Game shows

3.3LCD Background:

One of the most common devices attached to a micro controller is an LCD display. Some of the

most common LCD’s connected to the many microcontrollers are 16x2 and 20x2 displays. This

means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively.

Basic 16x 2 Characters LCD

The LCD requires 3 control lines as well as either 4 or 8 I/O lines for the data bus. The

user may select whether the LCD is to operate with a 4-bit data bus or an 8-bit data bus. If a 4-bit

data bus is used the LCD will require a total of 7 data lines (3 control lines .The three control

lines are referred to as EN, RS, and RW..The EN line is called "Enable." This control line is used

to tell the LCD that we are sending it data. To send data to the LCD, our program should make

sure this line is low (0) and then set the other two control lines and/or put data on the data bus.

When the other lines are completely ready, bring EN high (1) and wait for the minimum amount



Of time required by the LCD datasheet (this varies from LCD to LCD), and end by bringing it

low (0) again.

Figure 3.3.1: LCD Pin diagram

3.3.1Pin description:




PIN NO.

NAME

DESCRIPTION

PIN NO.1

VSS

POWER

SUPPLY(GND)

PIN NO.2

VCC

POWER

SUPPLY(+5V)

PIN NO.3

VEE

CONTRAST

ADJUST

PIN NO.4

RS

0=INSTRUCTION

INPUT

1=DATA INPUT

PIN NO.5

R/W

0=WRITE TO LCD

1=READ FROM

LCD

PIN NO.6

EN

ENABLE SIGNAL

PIN NO.7

D0

DATA BUS LINE

0 (LSB)

PIN NO.8

D1

DATA BUS LINE

1

PIN NO.9

D2

DATA BUS LINE

2

PIN NO.10

D3

DATA BUS LINE

3

PIN NO.11

D4

DATA BUS LINE

4

PIN NO.12

D5

DATA BUS LINE

5

PIN NO.13

D6

DATA BUS LINE

6

PIN NO.14

D7

DATA BUS LINE

7( MSB)


Table 3.3.2 Character LCD pins with Microcontroller

The RS line is the "Register Select" line. When RS is low (0), the data is to be treated as a

command or special instruction (such as clear screen, position cursor, etc.). When RS is high (1),

the data being sent is text data which should be displayed on the screen. For example, to display

the letter "T" on the screen we would set RS high The RW line is the "Read/Write" control line.

When RW is low (0), the information on the data bus is being written to the LCD.

An 8051 program must interact with the outside world using input and output devices that

communicate directly with a human being. One of the most common devices attached to an 8051

is an LCD display. Some of the most common LCDs connected to the 8051 are 16x2 and 20x2

displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines,

respectively. Fortunately, a very popular standard exists which allows us to communicate with

the vast majority of LCDs regardless of their manufacturer. The standard is referred to as


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMHD44780U, which refers to the controller chip which receives data from an external source (in

this case, the 8051) and communicates directly with the LCD.

Fig 3.3.2 Interfacing of lcd with microcontroller

PIN ASSIGNMENT:



INTERFACE TIMING (DATA WRITE)



.

Technical Specifications:

Power Requirements: 5 VDC

Communication: 4-bit or 8-bit Parallel Interface

Dimensions: ~3.25L x ~1.75W x 0.25H in (~85L x ~45W x ~6H mm)

Operating Temperature32° to +158° F (0° to + 70° C)

An 8051 program must interact with the outside world using input and output devices

that communicate directly with a human being. One of the most common devices attached to an

8051 is an LCD display. Some of the most common LCDs connected to the 8051 are 16x2 and

20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines,

respectively.

3.4 LED:

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as

indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical

electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions

are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.

The internal structure and parts of a led are shown in figures 3.4.1 and 3.4.2 respectively.



Fig 3.4.1: Inside a LED Fig 3.4.2: Parts of a LED

Working:

The structure of the LED light is completely different than that of the light bulb.

Amazingly, the LED has a simple and strong structure. The light-emitting when a diode is

forward biased (switched on), electrons are able to recombine with holes within the device,

releasing energy in the form of photons. This effect is called electroluminescence and the color of

the light (corresponding to the energy of the photon) is determined by the energy gap of the

semiconductor.

An LED is usually small in area (less than 1 mm2), and integrated optical components are used to

shape its radiation pattern and assist in reflection. LED’s present many advantages over

incandescent light sources including lower energy consumption, longer lifetime, improved

robustness, smaller size, faster switching, and greater durability and reliability. However, they are

relatively expensive and require more precise current and heat management than traditional light

sources. The compact size of LED’s has allowed new text and video displays and sensors to be

developed, while their high switching rates are useful in advanced communications technology.

The electrical symbol and polarities of led are shown in fig: 3.4.3.



Fig 3.4.3: Electrical Symbol & Polarities of LED

LED lights have a variety of advantages over other light sources:

High-levels of brightness and intensity

High-efficiency

Low-voltage and current requirements

Low radiated heat

Applications of LED fall into three major categories:

Visual signal application where the light goes more or less directly from the LED to the human

eye, to convey a message or meaning.

Illumination where LED light is reflected from object to give visual response of these object

A light-emitting diode (LED) is a semiconductor device that emits incoherent narrow-spectrum

light when electrically biased in the forward direction of the p-n junction. This effect is a form of

electroluminescence.

An LED is usually a small area source, often with extra optics added to the chip to shape its

radiation pattern [10]. The color of the emitted light depends on the composition and condition of

the semiconducting material used, and can be infrared, visible, or near-ultraviolet. This effect is

called electroluminescence and the color of the light (corresponding to the energy of the photon)

is determined by the energy gap of the semiconductor. An LED is usually small in area (less than

1 mm2), and integrated optical components are used to shape its radiation pattern and assist in



reflection. LED’s present many advantages over incandescent light sources including lower

energy consumption.


Color Maximum Forward Voltage

Infrared 1.6V

Red 1.8 V to 2.1 V

Orange 2.

Yellow

2.4V

Green

2.6V

Blue

3.0 V to 3.5 V

White

3.0 V to 3.5 V

Ultraviolet

3.5V


3.5 RF Transmitter

General Description: The ST-TX01-ASK is an ASK Hybrid transmitter module. ST-

TX01-ASK is designed by the Saw Resonator, with an effective low cost, small size, and

simple-to-use for designing.

Frequency Range: 315 / 433.92 MHZ.

Supply Voltage: 3~12V.

Output Power: 4~16dBm

Circuit Shape: Saw

Fig: 3.5.1 315/434 MHz TRANSMITTER



Fig: 3.5.2 433 MHz RF Transmitter STT-433

Pin Description:

ANT: 50 ohm antenna output. The antenna port impedance affects output power and harmonic

emissions. An L-C low-pass filter may be needed to sufficiently filter harmonic emissions.

Antenna can be single core wire of approximately 17cm length or PCB trace antenna

VCC: Operating voltage for the transmitter. VCC should be bypassed with a .01uF ceramic

capacitor and filtered with a 4.7uF tantalum capacitor. Noise on the power supply will degrade

transmitter noise performance

DATA: Digital data input. This input is CMOS compatible and should be driven with CMOS

level inputs.

GND: Transmitter ground. Connect to ground plane.The STT-433 is ideal for remote control

applications where low cost and longer range is required. The transmitter operates from a 1.5-

12V supply, making it ideal for battery- powered applications. The transmitter employs a SAW-

stabilized oscillator, ensuring

Features of RF transmitter:

433.92 MHz Frequency

Low Cost

1.5-12V operation


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM 11mA current consumption at 3V

Small size

dBm output power at 3V

Specifications of RF transmitter:

1. Operating Voltage Vcc: 1.5 to 12 Volts DC

2. Operating Current: Icc - 11mA @3V, 59mA @5V

3. Frequency Accuracy: -75 to 75 KHz

4. Center Frequency: 433 Mhz

5. RF Output Power: 4 dBM@3V (2 mW), 16 dBM@5V (39 mW)

6. Data Rate: 200 to 3K bps

7. Temperature:-20 to +60 Deg. C

8. Power up delay: 20 ms

Theory:

OOK (On off Keying) modulation is a binary form of amplitude modulation. When a

logical 0 (data line low) is being sent, the transmitter is off, fully suppressing the carrier. In this

state, the transmitter current is very low, less than 1mA. When a logical 1 is being sent, the

carrier is fully on. In this state, the module current consumption is at its highest, about 11mA

with a 3V power supply.

OOK is the modulation method of choice for remote control applications where power

consumption and cost are the primary factors. Because OOK transmitters draw no power when

they transmit a 0, they exhibit significantly better power consumption than FSK

transmitters.OOK data rate is limited by the start-up time of the oscillator. High-Q oscillators

which have very stable center frequencies take longer to start-up than low-Q oscillators.


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMData Rate: The oscillator start-up time is on the order of 40uSec, which limits the

maximum data rate to 4.8 kbit/sec. SAW stabilized oscillator: The transmitter is basically a

negative resistance LC oscillator whose center frequency is tightly controlled by a SAW

resonator. SAW (Surface Acoustic Wave) resonators are fundamental frequency devices that

resonate at frequencies much higher than crystals.

Applications:

1. Remote Keyless Entry (RKE)

2. Remote Lighting Controls

3. Wireless Alarm and Security Systems

4. Long Range RFID

5. Automated Resource Management

6. Wireless security systems

7. Car Alarm systems

8. Remote controls

9. Sensor reporting

3.6 RF Receiver:

General Description:

The ST-RX02-ASK is an ASK Hybrid receiver module. A effective low cost solution for using at

315/433.92 MHZ. The circuit shape of ST-RX02-ASK is L/C.

Receiver Frequency: 315 / 433.92 MHZ

Typical sensitivity: -105dBm

Supply Current: 3.5mA

IF Frequency: 1MHz

Features:


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM Low power consumption.

Easy for application.

Operation temperature range : ﹣20℃～＋70℃ Operation voltage: 5 Volts.

Fig: 3.5.2 315/434 MHz RECEIVER

Overview:

The STR-433 is ideal for short-range remote control applications where cost is a primary

concern. The receiver module requires no external RF components except for the antenna. It

generates virtually no emissions, making FCC and ETSI approvals easy. The Super-regenerative

design exhibits exceptional sensitivity at a very low cost. The manufacturing-friendly SIP style

package and low-cost make the STR-433 suitable for high volume applications

Features:

Low Cost

Voperation

3.5mA current drain

No External Parts are required

Receiver Frequency: 433.92 MHZ

Typical sensitivity: -105dBm

IF Frequency: 1MHz

433.92 MHz Frequency

Low Cost SPHOORTHY ENGINEERING COLLEGE 42

AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM 1.5-12V operation

11mA current consumption at 3V

Small size

dBm output power at 3V

Pin Diagram of RF Receiver:

FIG: 3.3.2 PIN DIAGRAM OF RF RECEIVER

Pin Name Description:

ANT: Antenna input.

GND: Receiver Ground. Connect to ground plane.

VCC: (5V) VCC pins are electrically connected and provide operating voltage for the receiver.

VCC can be applied to either or both. VCC should be bypassed with a .1μF ceramic capacitor.

Noise on the power supply will degrade receiver sensitivity.

DATA: Digital data output. This output is capable of driving one TTL or CMOS load. It is a

CMOS compatible output.

Operation: SPHOORTHY ENGINEERING COLLEGE 43

AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMThe STR-433 uses a super-regenerative AM detector to demodulate the incoming AM

carrier. A super regenerative detector is a gain stage with positive feedback greater than unity so

that it oscillates. An RC-time constant is included in the gain stage so that when the gain stage

oscillates, the gain will be lowered over time proportional to the RC time constant until

the oscillation eventually dies.

When the oscillation dies, the current draw of the gain stage decreases, charging the RC

circuit, increasing the gain, and ultimately the oscillation starts again. In this way, the oscillation

of the gain stage is turned on and off at a rate set by the RC time constant.

This rate is chosen to be super-audible but much lower than the main oscillation rate.

Detection is accomplished by measuring the emitter current of the gain stage. Any RF input

signal at the frequency of the main oscillation will aid the main oscillation in restarting.

If the amplitude of the RF input increases, the main oscillation will stay on for a longer

period of time, and the emitter current will be higher. Therefore, we can detect the original base-

band signal by simply low-pass filtering the emitter current.

The average emitter current is not very linear as a function of the RF input level. It

exhibits a 1/ln response because of the exponentially rising nature of oscillator start-up. The steep

slope of a logarithm near zero results in high sensitivity to small input signals. This rate is chosen

to be super-audible but much lower than the main oscillation rate. Detection is accomplished by

measuring the emitter current of the gain stage.

The most common source for NRZ data is from a UART embedded in a micro-controller.

Applications that use NRZ data encoding typically involve microcontrollers.

Power Supply: The STR-433 is designed to operate from a 5V power supply. It is crucial that

this power supply be very quiet. 11mA current consumption at 3V.The power supply should be

bypassed using a 0.1uF low-ESR ceramic capacitor and a 4.7uF tantalum capacitor.

These capacitors should be placed as close to the power pins as possible. The STR- 433 is

designed for continuous duty operation. From the time power is applied, it can take up to


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM750mSec for the data output to become valid. The Super-regenerative design exhibits exceptional

sensitivity at a very low cost.

Schematic Diagram



FIG



1.Schematic Diagram



3.7 ANALOG SENSORS

Features

Analog sensors give both a voltage signal 0-10V, and current signal 0-20mA.

Analog sensors may be used for distance, thickness control of conveyor belts, detection of

unevenness, positioning, continuous level-control, max-control with variable hysteresis as

well as for counting and control, to name but a few, they are particularly suited for use in

measuring techniques and control systems and are PLC-compatible.

Analog sensors give a signal output which is Proportional to sensing distance.

General:

In common with capacitive and inductive sensors the analog sensor also consists of a transistor

oscillator. The oscillator current will be influenced by the approach of metals and electric

conductive media to the inductive analog sensors or by metals and all non-metals.

FIG3.7.1INDUCTIVE ANALOG SENSOR



FIG:3.7.2 CAPACITIVE ANALOG

3.8 MAX 232

The MAX232 is a dual driver/receiver that includes a capacitive voltage generator to

supply TIA/EIA-232-F Voltage levels from a single 5-V supply. Each receiver converts

TIA/EIA-232-F inputs to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3

V, a typical hysteresis of 0.5 V, and can accept ±30-V inputs. Each driver converts TTL/CMOS

input levels into TIA/EIA-232-F levels.

3.9 RS 232

The MAX220–MAX249 family of line drivers/receivers is intended for all EIA/TIA-232E

and V.28/V.24 communications interfaces, particularly applications where ±12V is not available.

These parts are especially useful in battery-powered systems, since their low-power shutdown

mode reduces power dissipation to less than 5μW. The MAX225, MAX233, MAX235, and

MAX245/MAX246/MAX247 use no external components and are recommended for applications

where printed circuit board space is critical.



CHAPTER 4

INTRODUCTION TO KEIL SOFTWARE

4.1 KEIL µVision IDE Overview

The µVision IDE from Keil combines project management, make facilities, source code

editing, program debugging, and complete simulation in one powerful environment. The µVision

development platform is easy-to-use and it helps you quickly create embedded programs that

work. The µVision editor and debugger are integrated in a single application that provides a

seamless embedded project development environment.

µVision is the Keil Integrated Development and Debugging Environment that helps you

quickly create and test embedded applications for ARM7, ARM9, Cortex-M3, C16x, ST10,

XC16x, C251, and C51 embedded micro controllers. It combines all aspects of embedded project

development including source code editing, project organization and management, revision

control, make facility, target debugging, simulation, and Flash programming. µVision offers a

significant advantage to new users and to developers who must get projects working quickly.

A51 Macro Assembler

The A51 Assembler is a macro assembler for the 8051 family of microcontrollers. It

supports all 8051 derivatives. It translates symbolic assembly language mnemonics into

relocatable object code where the utmost speed, small code size, and hardware control are

critical.

The A51 assembler translates assembler source files into a relocatable object modules. The

DEBUG directive adds full symbolic information to the object module and supports debugging

with the µVision Debugger or an in-circuit emulator.

In addition to object files, the A51 assembler generates list files which may optionally

include symbol table and cross reference information.



C51 C Compiler

Compiler Details

Compiler Directives

Code Optimizer

Memory Models

Memory Types

Pointers

Interrupt Functions

Library Reference

The Keil C51 C Compiler for the 8051 microcontroller is the most popular 8051 C

compiler in the world. It provides more features than any other 8051 C compiler available today.

The C51 Compiler allows you to write 8051 microcontroller applications in C that,

once compiled, have the efficiency and speed of assembly language. Language extensions in the

C51 Compiler give you full access to all resources of the 8051.

The C51 Compiler translates C source files into reloadable object modules which contain full

symbolic information for debugging with the µVision Debugger or an in-circuit emulator. In

addition to the object file, the compiler generates a listing file which may optionally include

symbol table and cross reference information.

FEATURES:

Nine basic data types, including 32-bit IEEE floating-point,

Flexible variable allocation with bit, data, bdata, idata, xdata, and pdata memory types,

Interrupt functions may be written in C,

Full use of the 8051 register banks, Complete symbol and type information for source-level

debugging,

Built-in interface for the RTX51 Real-Time Kernel,

Support for dual data pointers on Atmel, AMD, Cypress, Dallas Semiconductor, Infineon,

Philips, and Triscend microcontrollers,

Support for the Philips 8xC750, 8xC751, and 8xC752 limited instruction sets,

Support for the Infineon 80C517 arithmetic unit.



BL51 Code Banking Linker/Locator

The BL51 code banking linker/locator combines OMF51 object modules and creates

executable 8051 programs. The linker resolves external and public references and assigns

absolute or fixed addresses to reloadable program segments.

The BL51 Linker processes object files created by the Keil C51 Compiler and A51

Assembler and the Intel PL/M-51 Compiler and ASM-51 Assembler. These object modules must

adhere to the OMF51 object module specification. BL51 outputs an absolute OMF51 object

module that may be loaded into practically any emulator, the Keil µVision Debugger, or the

OH51 Object-HEX converter (to create an Intel HEX file).

OH51 Object-HEX Converter

The OH51 Object-HEX converter creates Intel HEX files from absolute OMF51 object

modules. Absolute object files may be created by the following:

The BL51 code banking linker.

The A51 assembler.

The OC51 banked object converter.

Intel HEX files are ASCII files that contain a hexadecimal representation of your program. They

may be easily loaded into a device programmer for writing EPROMs or other memory devices.

Several utilities are available that may help you with your HEX files:

HEX2BIN converts an Intel HEX file into a flat BINARY file.

BIN2HEX converts a flat BINARY file into an Intel HEX file.

The following documents provide additional information about the different output file

formats.

Description of the Intel OMF51 Object Module Format.

Description of the Intel HEX File Format.



OC51 Banked Object Converter

The OC51 banked object file converter creates an absolute object module for each code

bank in a banked object module. You do not need this utility unless you have created a code

banking program using the BL51 code banking linker.

When you create a code banking application, all symbolic and source-level information is

maintained in the banked object module and is transferred by OC51 to each individual absolute

object module for each code bank.

Once you have used OC51 to create the absolute object modules, you may use OH51 to

create an Intel HEX file for each code bank.

Why You Need A Simulator

We agree that you can probably create, test, and debug your embedded applications

without a simulator. However, there are several reasons why a simulator (like the µVision

Debugger) can make your engineering tasks easier and save you lots of development time.

Customers with the simulator spend less time debugging simple program errors. The

simulator lets them learn about things like on-chip peripherals and addressing modes without

designing real hardware

It is our experience that customers who have a simulator require LESS technical support

and are able to get up-to-speed with the tools faster. The simulator makes it easy to write and test

code and learn about programming your microcontroller.

The µVision Debugger provides complete simulation support for on-chip peripherals like

PWM, Power saving modes, A/D, Serial I/O, and so on.

It is easier for our support engineers to explain complex problems if you have a simulator.



It is easier to discover if a problem is in the hardware or software when you use a

simulator. For example, if the application works in the simulator and if it works in the emulator,

there's most likely a problem with the target hardware.

The simulator requires no setup time. An emulator may require configuration and a target

board before you can debug.

The simulator is not a replacement for an emulator. A simulator is a different tool

entirely. While an emulator allows you to debug software running on your target hardware, a

simulator allows you to debug your software as well as your understanding of the microcontroller

and the programming language. There are no real-time debugging effects of a simulator.

For debugging embedded applications, we have a general list of favorite tools that we use

in- house.

Logic Probe

Digital Multi-Meter

High-speed Analog Oscilloscope

High-speed Digital Storage Oscilloscope

Logic Analyzer (with a disassembly pod)

Emulator

Software Simulator

4.2 Embedded C Features:

Memory Areas

Memory Types

Memory Models

Memory Type Specifiers


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM Variable Data Type Specifiers

Bit Variables and Bit-addressable Data

Special Function Registers

Pointers

Function Attributes

4.3 Memory Areas

The 8051 architecture supports several physically separate memory areas or memory

spaces for program and data. Each memory area offers certain advantages and disadvantages.

There are memory spaces that may be:

_ read from but not written to.

_ read from or written to

._ read from or written to more quickly than other memory spaces.

This wide variety of memory space is quite different from most mainframe,

minicomputer, and microcomputer architectures where the program, data, and constants are all

loaded into the same physical memory space within the computer. Refer to the Intel 8-Bit

Embedded Controllers handbook or other 8051 data books for more information about the 8051

memory architecture.

4.4 Code Memory

Program (CODE) memory is read only; it cannot be written to. Program memory may

reside within the 8051 CPU, it may be external, or it may be both, depending upon the 8051

derivative and the hardware design. There may be up to 64 KBytes of program memory. Program

code, including all functions and library routines, is stored in program memory. Constant

variables may also be stored in program memory. The 8051 executes programs stored in program

memory only. Program memory may be accessed using the code memory type specifier in the

Cx51 compiler.

Internal Data Memory


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMInternal data memory resides within the 8051 CPU and is read/write. Up to 256 bytes of

internal data memory are available depending upon the 8051 derivative. The first 128 bytes of

internal data memory are both directly and indirectly addressable. The upper 128 bytes of data

memory (from 0x80 to 0xFF) can be addressed only indirectly. There is also a 16 byte area

starting at 20h that is bit-addressable. Access to internal data memory is very fast because it can

be accessed using an 8-bit address. However, internal data memory is limited to a maximum of

256 bytes.

Internal data can be broken down into three distinct memory types: data, I data, and b

data. The data memory specified always refers to the first 128 bytes of internal data memory.

Variables stored here are accessed using direct addressing. The I data memory specified refers to

all 256 bytes of internal data memory; however, this memory type specified code is generated by

indirect addressing which is slower than direct addressing. The b data memory specified refers to

the 16 bytes of bit-addressable memory in the internal data area (20h to 2Fh). This memory type

specified allows you to declare data types that can also be accessed at the bit.

External Data Memory

External data memory is read/write. Access to external data is slower than access to

internal data memory because the external data memory is indirectly accessed through a data

pointer register which must be loaded with an address. Several 8051 devices provide on-chip

XRAM space that is accessed with the same instructions as the traditional external data space.

This XRAM space is typically enabled via dedicated chip configuration SFR registers and

overlaps the external memory space. There may be up to 64 KBytes of external data memory;

though, this address space does not necessarily have to be used as memory.

The Cx51 Compiler offers two different memory types that access external data:

xdata and pdata.

The xdata memory specifier refers to any location in the 64 KByte address space of

external data memory.

The pdata memory type specifier refers to only one (1) page or 256 bytes of external data

memory. See “Compact Model” on page 95 for more information on pdata.

Special Function Register Memory SPHOORTHY ENGINEERING COLLEGE 56

AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEMThe 8051 provides 128 bytes of memory for Special Function Registers (SFRs). SFRs

are bit, byte, or word-sized registers that are used to control timers, counters, serial I/O, port I/O,

and peripherals.

4.5Dumping steps:

Initially before connecting the program dumper to the microcontroller kit the window is

appeared as shown below.

Fig 4.5.1.: Picture of program dumper window

Select Tools option and click on Check Communication for establishing a connection as

shown in below window



Fig 4.5.2: Picture of checking communications before dumping

Program into microcontroller

After connecting the dumper properly to the microcontroller kit the window is appeared as shown

below.



Fig 4.5.3: Picture after connecting the dumper to microcontroller


AERONAUTICAL CRASH PREVENTION THROUGH RF COMMUNICATION SYSTEM Again by selecting the Tools option and clicking on Check Communication the

microcontroller gets recognized by the dumper and hence the window is as shown below.

Fig 4.5.4: Picture of dumper recognition to microcontroller



Import the program which is ‘.hex’ file from the saved location by selecting File option

Fig 4.5.5: Picture of program importing into the microcontroller



After clicking on ‘Import Hex’ option we need to browse the location of our program and click

the ‘prog.hex’ and click on ‘open’ for dumping the program into the microcontroller.

Fig 4.5.6: Picture of program browsing which is to be dumped



After the successful dumping of program the window is as shown below.

Fig 4.5.7: Picture after program dumped into the microcontroller



CHAPTER 5

CODING



CHAPTER 6

RESULT

The project “AERONAUTICAL CRASH PREVENTION THROUGH RF

COMMUNICATION SYSTEM” was designed to operate a toll gate using RF remote.

Also, the total vehicle count is displayed on LCD. The project has been executed successfully.



CHAPTER 7

7.1CONCLUSION:

Integrating features of all the hardware components used have been developed in it.

Presence of every module has been reasoned out and placed carefully, thus contributing to the

best working of the unit. Secondly, using highly advanced IC’s with the help of growing

technology, the project has been successfully implemented. Thus the project has been

successfully designed and tested.

7.2 FUTURE SCOPE:

Our project “RF based toll gate with vehicle counter” is mainly intended to to

operate a toll gate using RF remote. Also, the total vehicle count is displayed on LCD. This

operation is performed through an intelligent device called Microcontroller.

The main drawback of this system is it uses wireless RF communication which

gives the communication only for limited distance. Zigbee can be used to increase the distance.



CHAPTER 8

BIBLIOGRAPHY:

1. WWW.ATMEL.DATABOOK.COM

2. WWW.KEIL.COM

3. WWW.WIKIPEDIA.COM


http://WWW.WIKIPEDIA.COM/

http://WWW.KEIL.COM/

http://WWW.ATMEL.DATABOOK.COM/


CHAPTER 9

REFERENCES:

Microcontrollers Architecture, Programming, Interfacing and System Design.

BY: - Raj kamal–

Embedded system

BY: - Mazda and Mazidi

PCB Design Tutorial

BY:- David.L.Jones.

PIC Microcontroller Manual –

BY:-Microchip..

Embedded C

BY:-Michael.J.Pont.


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