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Intelligent Ambulance for City Traffic Police

1. INTRODUCTION
In recent years due to globalization there has been a sudden rise in the demand for automated traffic control systems especially in urban areas. This requires an adaptive method actuated by vehicles that adopts logic programming to model and solve the decision problems associated with traffic control. Such a method can be applied with success to urban intersections with high levels of traffic where many different and unpredictable events contribute to large fluctuations in the number of vehicles that use the intersection. The term Intelligent Traffic Control has been adopted to address the latest generation of traffic control methods, that deploy sophisticated modelling and optimisation tools to try and meet the demand for a more efficient and effective way to manage the movements of a large number of vehicles and easy movement of special vehicles viz. VIP vehicles, Ambulances etc. In practice, there are various types of traffic control systems that are used to regulate traffic. For example, use of counters and timers to control the traffic lights. This system however does not control the traffic efficiently due to the ever increasing congestion of traffic. Here the signal phases and cycle length are predetermined using historical data; the time period of green light is predetermined and it continues to be the same throughout the day, if no sensory input is received. In our case the predetermined time for green light is 5 seconds. The system deals with the signal phase lengths that are adjusted in response to traffic flow, as registered by the actuation of vehicle and/or pedestrian detectors; if a sensory output is received by the controller, it adjusts the time period of green light for the next road.

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Intelligent Ambulance for City Traffic Police Suppose we are using only the output from the sensors then the drawback is that suppose in a low congested road an ambulance or a high priority vehicle comes it will not be signalled unless and until the congestion is avoided so to deal with this situation we are planning to in incorporate RFID modules which will prioritize the signals based on the traffic for only important vehicles Our proposed traffic control system has been designed for a congested, single intersection of an urban area. Traffic detection is carried out by various obstacle sensors that continuously provide information on the volume of traffic on each lane and the RFID's that are mounted on the special vehicles.

1.1 Specification:
Microcontroller Sensors Access Mechanism Communication Protocol Display System OS Platform P89V51RD2 [8051] IR Modulation sensors RFID + 2 Tags RS232 LEDs Linux, Windows

Table 1.1 – Specifications of Intelligent Traffic Controller

1.2 Block diagram

OBSTACLE SENSOR

LED

MICRO CONTROLLER

RFID

Figure 1.1 – Block Diagram of Intelligent Traffic control

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2. THE MICROCONTROLLER
The P89V51RB2/RC2/RD2 are 80C51 microcontrollers with 16/32/64 kB Flash and 1024 bytes of data RAM. A key feature of the P89V51RB2/RC2/RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI.The Flash program memory supports both parallel programming and in serial In-System Programming (ISP). Parallel programming mode offers gang-programming at high speed, reducing programming costs and time to market. ISP allows a device to be reprogrammed in the end product under software control. The capability to field/update the application firmware makes a wide range of applications possible. The P89V51RB2/RC2/RD2 is also In-Application Programmable (IAP), allowing the Flash program memory to be reconfigured even while the application is running.

2.1 Features
• • • • • • • • • • 80C51 Central Processing Unit 5 V Operating voltage from 0 MHz to 40 MHz 16/32/64 kB of on-chip Flash user code memory with ISP (InSystem Programming) and IAP (In-Application Programming) Supports 12-clock (default) or 6-clock mode selection via software or ISP SPI (Serial Peripheral Interface) and enhanced UART PCA (Programmable Counter Array) with PWM and Capture/Compare functions Four 8-bit I/O ports with three high-current Port 1 pins (16 mA each) Three 16-bit timers/counters Programmable watchdog timer Eight interrupt sources with four priority levels Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 3

Intelligent Ambulance for City Traffic Police • • • • • Second DPTR register Low EMI mode (ALE inhibit) TTL- and CMOS-compatible logic levels Brown-out detection Low power modes a. Power-down mode with external interrupt wake-up b. Idle mode DIP40, PLCC44 and TQFP44 packages



2.2 Block Diagram

Figure 2.1 – Block Diagram of Microcontroller

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2.3 Pinning Information

Figure 2.2 – Pin configuration

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Figure 2.3 – Another look of Pin Configuration

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2.4. Pin Multiplexing
As you will see in the following table, a no. of I/O pins have more than one functions. i.e. a pin may be used as a simple input pin or a serial communication receiver. This is called pin multiplexing. Using pin multiplexing, a pin can be used for more than one function. How is this possible? How can a pin be used for both purposes at the same time? Well, it’s not. The pin is used for only one purpose at a time. Pin multiplexing simply allows the pin to be used for different applications at different times. Thus, to use a pin as an input or a serial receiver, we just have to initialize the pin by configuring the specific register. But why to make it so complex? Why not just have a single pin for input port and another as a serial receiver? As you go through the table below, you will find that some of the pins satisfy as many as 3 functions. To replace 3 pins for every such pin will increase the pin count dramatically. To accommodate all the pins, the size of the IC will increase. Ultimately, you will end up with an IC as big as your palm, if not more! Hence, pin multiplexing helps to reduce the size of the IC without compromising in the features of the microcontroller.

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2.5 Pin Description:
SYM BOL P0.0 to P0.7 P1.0 to P1.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 to P2.7 P3.0 to P3.7 P3.0 P3.1 P3.2 P3.3 DESCRIPTION Port 0: Port 0 is an 8-bit open drain bi-directional I/O port. i.e. we can program the Port P0 to use its pins either as Inputs or as Outputs. To use these port pins as inputs, external pull up resistors should be connected. The need of pull up resistors is explained later. Pull up resistors are not essential for operating P0 as an output port. Port 1: Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 pins are pulled high by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. Apart from general purpose I/O Ports, P1 also has the following alternative functions. T2: Counter input to Timer/Counter 2 or Clock-output from Timer/Counter 2 T2EX: Timer/Counter 2 capture/reload trigger and direction control ECI: External clock input. This signal is the external clock input for the PCA CEX0: Capture/compare external I/O for PCA Module 0. Each capture/compare module connects to a Port 1 pin for external I/O. When not used by the PCA, this pin can handle standard I/O. SS: Slave port select input for SPI CEX1: Capture/compare external I/O for PCA Module 1 MOSI: Master Output Slave Input for SPI CEX2: Capture/compare external I/O for PCA Module 2 MISO: Master Input Slave Output for SPI CEX3: Capture/compare external I/O for PCA Module 3 SCK: Master Output Slave Input for SPI CEX4: Capture/compare external I/O for PCA Module 4 Port 2: Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 pins are pulled HIGH by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. . Apart from general purpose I/O Ports, P2 also has the following alternative functions. Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins are pulled HIGH by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. . Apart from general purpose I/O Ports, P3 also has the following alternative functions. RXD: serial input port TXD: serial output port INT0: external interrupt 0 input INT1: external interrupt 1 input Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 8

Intelligent Ambulance for City Traffic Police P3.4 P3.5 P3.6 P3.7 T0: external count input to Timer/Counter 0 T1: external count input to Timer/Counter 1 WR: external data memory write strobe RD: external data memory read strobe Program Store Enable: PSEN is the read strobe for external program memory. When the device is executing from internal program memory, PSEN is inactive (HIGH). When the device is executing code from external program memory, PSEN is activated twice each machine cycle. Reset: While the oscillator is running, a HIGH logic state on this pin for two machine cycles will reset the device. If the PSEN pin is driven by a HIGH-to-LOW input transition while the RST input pin is held HIGH, the device will enter the external host mode, otherwise the device will enter the normal operation mode. External Access Enable: EA must be connected to VSS in order to enable the device to fetch code from the external program memory. EA must be strapped to VDD for internal program execution. Address Latch Enable: ALE is used during accessing an external memory. This pin is also the programming pulse input (PROG) for flash programming. XTAL 1 XTAL 2 VDD VSS Power supply Ground
Table 2.1 – Pin Details

RST

Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits. Crystal 2: Output from the inverting oscillator amplifier.

2.6 Pull Up Resistors
Pull up resistors are used on the input side so that the input pins are at an expected logic level even if they are disconnected from the input switches. If Pull Up resistors are not used, the voltage level at the input pin will be floating in such a case and hence the outcome of the circuit is unpredictable. Consider the following circuit: Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 9

Intelligent Ambulance for City Traffic Police

/ ------_____/ -------| |--| ---| |--| ---| |--\/ -------

GND Here, a switch is connected at the input pin of a microcontroller. Note the absence of a pull up resistor. When the switch is closed, the pin is directly grounded and the input pin reads a logic level 0. Thus logic level 0 should indicate that the switch is closed. Now consider when the switch is open. The input pin is not connected to anything else, hence the pin in open. Thus the input pin is said to be kept floating. i.e. the voltage at the pin may vary from 0 V to 5V randomly. Thus we cannot be sure every time that when the logic at pin is 0, it is because of the closed switch or the floating voltage. Hence this circuit is not appropriate. Now consider the circuit below: VCC
/\ | | / | ------_____/ -------| |--| ---| |--| ---| |--\/ -------

GND

This circuit will eliminate our problem of floating pin. It is obvious that when the pin is open, the voltage at the input pin is Vcc. But now imagine what will happen if the switch is closed. What do you think will the voltage be at the input pin? You don’t have the time to calculate that! You have shorted Vcc and ground of your Power Supply! This is a very wrong method to eliminate our original problem of floating voltage. Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 10

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Now see what’s happening here: VCC
/\ | | \ / Pull-up resistor \ | | / | ------_____/ -------| |--| ---| |--| ---| |--\/ -------

GND When the switch is closed, the pin is directly connected to ground and reads logic level 0. When the switch is opened, the pin is connected to Vcc through a high value resistor; hence it reads a logic value 1.

Thus, the use of pull up resistor has solved our problem. Note that a high value pull up resistor must be used to limit the current flow to ground when the switch is closed.

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3. 8051 TIMER/COUNTER PROGRAMMING
P89V51RD2 has 3 timers: T0, T1 and T2.They can be used as timers or event counters. Here we’ll discuss the timers’ registers and then show how to program the timers.

3.1 Timers 3.1.1 TIMER 0:
The 16-bit register of timer 0 is accessed as a low byte and high byte. The low byte register is called TL0 and the high byte register is referred to as TH0. These register can be addressed like any other registers, such as A, B, R0, R1 etc. The mode of Timer 0 is set in the TMOD register and it is controlled by the TCON register .

3.1.2 TIMER 1:
Timer 1 is also 16 bits, and its 16-bit register is split into 2 bytes, referred to as TL1 and TH1. These registers are accessible in the same way as registers of Timer 0. The mode of Timer 1 is set in the TMOD register and it is controlled by the TCON register .

3.1.3 TIMER 2:
Timer 2 is a 16-bit Timer/Counter, which can operate as either an event timer or an event counter, as selected by C/T2 in the special function register T2CON. Timer 2 has four operating modes: Capture, Auto-reload (up or down counting), Clock-out, and Baud Rate Generator, which are selected using T2CON and T2MOD

3.2 TMOD (timer mode) Register
Both Timers 0 and 1 use the same register, called TMOD, to set various timer operation modes. TMOD is an 8-bit register in which the lower 4 bits are set aside for Timer 0 and upper 4 bits for Timer1. In Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 12

Intelligent Ambulance for City Traffic Police each case, the lower 2 bits are used to set the timer mode and upper 2 bits are used to set the operation. These options are discussed next.

Table 3.1 - TMOD Register

3.2.1 M1, M0
M0 and M1 select the timer mode. There are 4 modes: 0, 1, 2 and 3. Mode 0 is a 13 bit timer, mode 1 is a 16 bit timer, mode 2 is an 8 bit timer and mode 3 is used as a split timing mode. We will concentrate on modes 1 and 2 since they are the ones used more widely.

3.2.2 C/T (counter /timer)
This bit is used to decide whether the timer is used as a delay generator or an event counter. If C/T =0, it is used as a timer for time delay generation. The clock source for time delay is the crystal frequency of the 8051.

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3.2.3 Clock source for timer
As you know, every timer needs a clock pulse to tick. What is the source of the clock pulse for the 8051 timers? If C/T= 0, the crystal frequency attached to the 8051 is the source of the clock of the timer. The frequency for the timer is always 1/12th of the frequency of the crystal attached to the 8051.

3.2.4 GATE
Every timer has a means of starting and stopping. The timers in the 8051 can be started by both, hardware and software means. The start and stop of the timer are controlled by means of software by the TR (timer start) bits TR0 and TR1. This is achieved by setting and clearing the TR bit. This starts and stops the timers as long as GATE=0. The hardware way of starting and stopping the timer by an external source is achieved by making GATE=1 in the TMOD register. For the time being, we will consider only the software control of timers.

3.2.5 16-bit Time Mode (mode 1)
Timer mode "1" is a 16-bit timer. This is a very commonly used mode. TLx is incremented from 0 to 255. When TLx is incremented from 255, it resets to 0 and causes THx to be incremented by 1. Since this is a full 16-bit timer, the timer may contain up to 65536 distinct values. If you set a 16-bit timer to 0, it will overflow back to 0 after 65,536 machine cycles.

3.2.6 8-bit Time Mode (mode 2)
Timer mode "2" is an 8-bit auto-reload mode. When a timer is in mode 2, THx holds the "reload value" and TLx is the timer itself. Thus, Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 14

Intelligent Ambulance for City Traffic Police TLx starts counting up. When TLx reaches 255 and is subsequently incremented, instead of resetting to 0 (as in the case of modes 0 and 1), it will be reset to the value stored in THx.

3.2.7 Initialization of Timers:
Following steps are to be followed to initialize and operate a timer in any mode: 1. Load TMOD value appropriately to specify the timer used, mode of timer, hardware/software control and operation (counter or timer) 2. Load TLx and THx according to the mode selected and the time delay desired. 3. Start the timer. ( Set TRx bit) 4. Keep monitoring the timer overflow flag (TFx) in the TCON register to see if it is raised. Get out of the loop when TFx becomes high. 5. Stop the timer. (Clear TRx bit)

Example:
Write a program to generate a square wave of frequency 1Khz at the pin P1.1. Assume a crystal of 11.0592 Mhz Frequency. In8051 one instruction cycle has 12 states. Therefore, the frequency of timer is 11.0592 Mhz /12 = 921.6 KHz. Therefore the time period of each count will be 1/921.6 = 0.001085 mS = 1.085 microseconds. For a square wave of 1 Khz, High time=Low time. Also, High Time + Low Time = (1/1Khz) = 1000 microseconds Therefore High time = Low time = 500 microseconds. Now, our problem is simplified. All we have to do is wait for a time period of 500 microseconds, and then toggle the pin P1_1. To wait for 500 microseconds, we have to count up to 500/1.085 = 461 (approx). Now looking at all the available modes, we see that the 16 Bit timer mode is best suited for this application. Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 15

Intelligent Ambulance for City Traffic Police (461)D = (01CD)H thus to initialize the timers, we have to load 01 in TH0 and CD in TL0. Given below is the solution program:

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Intelligent Ambulance for City Traffic Police #include<p89v51rd2.h> void delay(); void main() { delay(); while(1) { P1_1=~P1_1; delay(); } } void delay() { TMOD= 0x01; TH0=0x01; TL0= 0xCD; TR0=1; while(TF0==0) ; TR0=0; } // select timer 0 in mode 1 (16 Bit) // enter count for 500 microseconds // “ //start timer 0 // wait for timer 0 overflow flag to be set //stop timer 0 //toggle P1_1 //wait for 500 microseconds //call delay //do continuously //include device file //declare function

3.2.8 Counter Programming
Recall from last section that C/T bit in the TMOD register decides the source of the clock for the timer. If C/T=0, the timer gets pulses from the crystal. In contrast, when C/T=1, the counter counts up as pulses are fed from pins 14 and 15. These pins are called T0 (timer 0 input) and T1 (timer 1 input). Thus pulses coming from these pins are counted in the TLx and THx registers according to the mode selected.

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3.2.9 Counter Operation
The counters have been included on the chip to relieve the processor of timing and counting chores. When the program wishes to count a certain number of internal pulses or external events, a number is placed in one of the counters. The counter increments from the initial number to the maximum and then rolls over to zero on the final pulse and also set a timer flag. The flag condition may be tested by an instruction to tell the program that the count has been accomplished. Observe the following chart:

Figure 3.1 –Flow chart of Counter

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3.3 TCON (timer control) Register
Timers 1 and 0 are controlled using the upper 4 bits of the TCON register. The lower 4 bits are used for setting interrupt function and will be discussed later. The TRx bits (TR0 and TR1) are used to start and stop the timers by software. The TFx bits (TF0 and TF1) are used to monitor the status of the timers. BIT NAME 7 TF1 6 TR1 5 TF0 4 TR0 3 IE1 2 IT1 1 IE0 0 IT0

Figure 3.2 – Block of TCON Register

3.4 8051 INTERRUPTS PROGRAMMING
There are two ways to monitor the status of an ongoing process or an external event: interrupts or polling:

3.4.1 Interrupts
If process in question (or external event) interrupts the microcontroller, asking it to execute a different program before carrying out the original program, we say an interrupt has occurred. The process can be timer operation or serial data transfer. The external event can be recognized by 2 pins on the 8051. And the “different program” id called the Interrupt Service Routine (ISR)

3.4.2 Polling
If a microcontroller keeps monitoring the status flags or inputs pins continuously until a state change occurs and then branches off to perform the rest of the program, the microcontroller is said to be polling for the flags (or inputs) Needless to say, using interrupts can result in faster and simultaneous operation of functions.

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Intelligent Ambulance for City Traffic Police The P89V51RD2 has the following 8 different interrupts: • • • • • Brown Out External Interrupts 0 and 1 Timer Interrupts 0, 1 and 2 Serial/SPI interrupt PCA

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3.4.3 The IEN0 and IEN1 (Interrupt Enable) Registers
By default at power up, all interrupts are disabled. This means that even if, for example, the TF0 bit is set, the 8051 will not execute the interrupt. Your program must specifically tell the 8051 that it wishes to enable interrupts and specifically which interrupts it wishes to enable. Your program may enable and disable interrupts by modifying the IEN0 and IEN1 SFR. Note that the EA bit in IEN0 should be enabled for any interrupt to operate. If EA is cleared, none of the interrupts will be activated irrespective of the status of other bits in IEN0 and IEN1.

IEN0:

IEN1:

Table 3.2 – Function of IEN0 and IEN1

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3.4.4 What Happens When an Interrupt Occurs?
When an interrupt is triggered, the following actions are taken automatically by the microcontroller: • • • • The current Program Address is saved. In the case of Timer and External interrupts, the corresponding interrupt flag is cleared. Program execution transfers to the corresponding Interrupt Service Routine address. The Interrupt Service Routine executes. Take special note of the 2nd step: If the interrupt being handled is a Timer or External interrupt, the microcontroller automatically clears the interrupt flag before passing control to your interrupt handler routine. This means it is not necessary that you clear the bit in your code.

3.4.5 What Happens When an Interrupt Ends?
An interrupt ends when your program executes the “Return from Interrupt” instruction. When the RETI instruction is executed the following actions are taken by the microcontroller: • • The saved Program Address is restored. Normal program execution is resumed.

3.5. PROGRAMMING TIMER INTERRUPTS
Before, we considered the operation of timers using the polling method. Now we will do the same using Interrupts. To initialize a timer interrupt, the corresponding bits in the IEN0 register should be set. Then we go about initializing the timer as described in the section above.

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Intelligent Ambulance for City Traffic Police Start the timer. When the timer rolls over from FFFF to 0000 (or FF to 00 in the 8 bit mode), the TFx flag is set. As soon as the TFx flag is set, interrupt occurs and the program control is shifted to ISR. After the ISR is executed, the TFx flag is cleared and program flow is returned to the original program. Example: Write a program to create a square wave of frequency 1Khz on pin P0.1. Simultaneously receive the data at P1 and send it to P2. Program: #include<p89v51rd2.h> void timer 0() interrupt 2 { P0_1=~P0_1; TR0=0; } void main() { IEN0=0x82; delay(); microseconds while(1) { P2=P1; } } void delay() { TMOD=0x01; TH0=0x01; TL0=0xCD; TR0=1; } // //select timer 0 in 16 bit mode //load count “ //start timer 0 //do continuously //enable interrupt for timer 0 //initialize timers and wait for 500 //interrupt service routine //toggle P0_1 //stop timer 0

// receive data from P1 and send it to P2

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3.6 PROGRAMMING EXTERNAL INTERRUPTS
To initialize an external interrupt, the corresponding bits in the IEN0 register should be set. The type of interrupt (low level/ High to Low edge) is determined by setting to IEx bits in the TCON register. (IEx=0: Low Level Interrupt, IEx=1: H-L Transition Interrupt) Whenever the appropriate signal is received on the input pins, (P3.2=Ext Int. 0, P3.3= Ext Int. 1), interrupt occurs and the program control is shifted to ISR. After the ISR is executed, the program flow is returned to the original program. The only thing that differentiates an ISR (Interrupt Service Routine) from a normal function is the syntax in which an ISR is defined. The syntax for defining an interrupt is as shown void ISR Name(void) interrupt x Eg: void TIMER0_OVF(void) interrupt 1 x Interrupt 0 Ext. Interrupt 0 (INT0) 1 Timer 0 Overflow 2 Ext. Interrupt 1 (INT1) 3 Timer 1 Overflow 4 UART 5 T2
Example on using timer interrupts

This code is for an LED blinking program using timers. The LEDs connected on P3_0, P3_6 and P3_7 will blink. #include unsigned char i=0,j=0,k=0; void timer2_ovf() interrupt 5 //Timer 2 ISR { k++; if(k==50) { k=0; RXD=!RXD; } TF2=0; //Reset overflow flag Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 24

Intelligent Ambulance for City Traffic Police } void timer0_ovf(void) interrupt 1 //Timer 0 ISR { i++; if(i==50) { i=0; RD=!RD; } } void timer1_ovf(void) interrupt 3 //Timer 1 ISR { j++; if(j==50) { j=0; WR=!WR; } } void main(void) { TMOD=0×11; //Set timer 0 and 1 in mode 1 T2CON=0×04; //Start timer 2 in 16 bit mode ET1=1; //Enable Timer 1 overflow interrupt ET0=1; //Enable Timer 0 overflow interrupt ET2=1; //Enable Timer 2 overflow interrupt TR0=1; //Timer 0 run TR1=1; //Timer 1 run EA=1; //Global Interrupt enable while(1){} }
Example on using external interrupts

In this you can see that the LEDs connected on the RD and WR (i.e. P3_6 and P3_7) pins glow when there is an external interrupt(i.e. switch is pressed)

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#include void ext_int0(void) interrupt 0 //INT0 ISR { RD=0; } void ext_int1(void) interrupt 2 //INT1 ISR { WR=0; } void main(void) { TCON=0×05; //Set interrupt type. Edge triggered in this case EX1=1; //Enable external interrupt 1 EX0=1; //Enable external interrupt 0 EA=1; //Global interrupt enable while(1){} }

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4. OBSTACLE SENSOR
4.1 Sensor
Sensors are the device that responds to a physical stimulus (heat, light, sound, pressure, motion, flow, and so on), and produces a measurable corresponding electrical signal

4.2 Sensor Technology
So far, we have considered mainly the nature and characteristics of EM radiation in terms of sources and behavior when interacting with materials and objects. It was stated that the bulk of the radiation sensed is either reflected or emitted from the target, generally through air until it is monitored by a sensor. The subject of what sensors consist of and how they perform (operate) is important and wide ranging Most remote sensing instruments (sensors) are designed to measure photons. The fundamental principle underlying sensor operation centers on what happens in a critical component - the detector. This is the concept of the photoelectric effect (for which Albert Einstein, who first explained it in detail, won his Nobel Prize [not for Relativity which was a much greater achievement]; his discovery was, however, a key step in the development of quantum physics). This, simply stated, says that there will be an emission of negative particles (electrons) when a negatively charged plate of some appropriate lightsensitive material is subjected to a beam of photons. The electrons can then be made to flow from the plate, collected, and counted as a signal. A key point: The magnitude of the electric current produced (number of photoelectrons per unit time) is directly proportional to the light intensity. Thus, changes in the electric current can be used to measure changes in the photons (numbers; intensity) that strike the plate (detector) during a given time interval. The kinetic energy of the released photoelectrons varies with frequency (or wavelength) of the impinging radiation. Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 27

Intelligent Ambulance for City Traffic Police But, different materials undergo photoelectric effect release of electrons over different wavelength intervals; each has a threshold wavelength at which the phenomenon begins and a longer wavelength at which it ceases.

4.3 Obstacle sensor
Obstacle sensor is a effective IR proximity sensor built with the TSOP 1738 module. The TSOP module is commonly found at the receiving end of an IR remote control system; e.g., in TVs, CD players etc. These modules require the incoming data to be modulated at a particular frequency and would ignore any other IR signals. There are various sources of IR sensors and our receiver must receive IR rays only from our source and ignore other IR Rays. It is also immune to ambient IR light, so one can easily use these sensors outdoors or under heavily lit conditions. Such modules are available for different carrier frequencies from 30 kHz to 56 kHz. In this particular proximity sensor, we will be generating a constant stream of square wave signal using IC555 centered at 38 kHz and would use it to drive an IR led. So whenever this signal bounces off the obstacles, the receiver would detect it and change its output. Since the TSOP 1738 module works in the active-low configuration, its output would normally remain high and would go low when it detects the signal (the obstacle)

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4.3.1 Schematic of TSOP sensor
Figure 4.1 – Schematic of TSOP

4.3.2 LM555 Timer
The LM555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive

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Figure 4.2 – LM 555 timer

4.3.3 Calculation for 555 Timer
This calculation is designed to give timing values for the 555 timer, based on the control capacitance and resistance. This particular configuration is for an astable square wave calculation. The positive output is high for T(h) seconds based on this formula: Time High (secs) = 0.693 * (R1 + R2) * C. The negative output is low for T(l) seconds based on this formula: Time Low (secs) =0.693 * R2 * C The frequency is derived by the formula: Frequency = 1.44 / ((R1 + R2 + R2) * C) The duty cycle percentage is the relationship of the high time to the overall cycle time and is derived by the formula: DCP = (T(h) / (T(h) + T(l))) * 100 Where resistance is in ohms and capacitance is in farads. Enter the capacitance in farads (not microfarads) and the resistance in ohms for each resistor. Click on Calculate to return the time high in seconds, the time low in seconds, the duty cycle percentage and the frequency in hertz.

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5. RFID
5.1 LF RFID MODULE
The DT125R series RFID Proximity OEM Reader Module has a built-inantenna in minimized form factor. It is designed to work on the industry standard carrier frequency of 125 kHz. This LF reader module with an internal or an external antenna facilitates communication with Read-Only transponders—type UNIQUE or TK5530 via the air interface. The tag data is sent to the host systems via the wired communication interface with a protocol selected from the module pinout. The LF DT125R module is best suited for applications in Access Control,Time and Attendance, Asset Management, Handheld Readers, Immobilizers, and other RFID enabled applications.

5.2 Features
• • • • • • • Selectable UART or Wigand26 Plug-and-Play, needs +5V to become a reader No repeat reads LED/Beeper indicates tag reading operation Excellent read performance without an external circuit Compact size and cost-effective A very efficient module for portable readers.

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5.3. Block Diagram

Figure 5.1 – Block diagram of RFID Module

The LF DT125R reader consists a RF front end interfaced with the baseband processor that operates with +5V power supply. An antenna is interfaced with the RF front end, and tuned at 125 kHz to detect a tag (transponder) that comes in the vicinity of the reader field. The data read from the tag by the front end is detected and decoded by the base band processor and is then sent to the UART interface. The DT125R is designed for a reading range of 50 mm to 100 mm. A LED and a beeper can be interfaced to the pin out to indicate the tag read status. DT125R has a built-in circuitry for noise reduction.

5.3.1 Data Transmission in ASCII Standard
Data read from the tag is Manchester encoded. The Manchester encoded data is decoded to ASCII standard. Decoded data is sent to the UART serial interface for wired communication with the host systems. ASCII data format is shown below: The 1byte (2 ASCII characters) Check sum is the “Exclusive OR” of the 5 hex bytes (10 ASCII) Data characters. It takes the full memory of the card from D00 to D93 and divides this memory into 10 groups of 4 bits. Group1= D00 to D03; Group2= D10 to D13 ……Group10= D90 to D93. Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 32

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The reader then takes the corresponding HEX value for each group of 4 bits 0…FHEX. This HEX value is now taken as ASCII characters and the reader transmits the ASCII value. STX (02h) DATA (10 ASCII) CHECK SUM (2 ASCII) CR LF ETX (03h)

5.3.2 Specifications:
Dimensions (LXBXH) mm Frequency Reading Distance Interface Antenna Supply Voltage Operating temperature Tag Types Output Format Color 30x30x10 125 kHz >= 50 mm UART, Wiegand26 Built-in and External +5 V 10°C to +50°C (-14°F to +122°F) Unique, TK5530 ASCII Black
Table 5.1 – Specifications of RFID Module.

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Figure 5.2 – Dimension of RFID Module

5.3.3 Pin Number Description
PIN PIN PIN PIN PIN PIN PIN PIN PIN PIN 1 2 3 4 5 6 7 8 9 10 1 LED/BEEPER Data1 Data0 GND TTL1 (TXD) TTL0 (RXD) NC VCC ANTENNA 1 ANTENNA 2
Table 5.2 – Pin Details

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Figure 5.3 – Bottom view of RFID Module

5.3.4 Schematic Diagram

Figure 5.4 – Schematic Diagram of RFID Module

5.4 Applications
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Applications of the RFID OEM LF DT125R Reader Module are limited by the imagination of the designer because of the compact form factor and low power consumption. Some of the common applications for this module are: • • • • • Access control Handheld readers Asset management Time and Attendance Immobilizers

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6. LIGHT EMITTING DIODES
Traffic lights, also known as traffic signals, stop lights, traffic lamps, stop-and-go lights, robots or semaphore, are signaling devices positioned at road intersections, pedestrian crossings, and other locations to control competing flows of traffic. Traffic lights have been installed in most cities around the world to control the flow of traffic. They assign the right of way to road users by the use of lights in standard colors (Red - Amber - Green), using a universal color code (and a precise sequence, for those who are color blind). They are used at busy intersections to more evenly apportion delay to the various users. The most common traffic lights consist of a set of three lights: red, yellow (officially amber), and green. When illuminated, the red light indicates for vehicles facing the light to stop; the amber indicates caution, either because lights are about to turn green or because lights are about to turn red; and the green light to proceed, if it is safe to do so. There are many variations in the use and legislation of traffic lights, depending on the customs of a country and the special needs of a particular intersection. There may, for example, be special lights for pedestrians, bicycles, buses, trams, etc; light sequences may differ; and there may be special rules, or sets of lights, for traffic turning in a particular direction. Complex intersections may use any combination of these.

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6.1 Traffic Lights
Traffic lights can have several additional lights for filter turns or bus lanes. This one in Warrington, also shows the distinctive red + amber combination seen in the UK. It also shows the backing board and white border used to increase the target value of the signal head. Improved visibility of the signal head is achieved during the night by using the retro-reflective white border In many regions, traffic lights function differently or have different displays depending on available technology, traffic patterns, or other vehicles such as trolleys that also use the intersection. For example, some fixtures feature a flashing green light or more than one arrow lit at one time. An example of a flashing green light found in Canada, to notify left turning drivers that they have the right of way and that the opposing lanes will not be moving.

6.1.1 Three Set Lights
Red Yellow Green Figure 6.1 – Three set Lights The universal standard is for the red to be above the green, and if there is also amber it is placed in the middle. If the three-set lights are mounted horizontally, the red will typically be to the left of the green. The standards apply whether the country drives on the left or the right, but the placement of the mountings on the road would be mirror images of the other.

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Intelligent Ambulance for City Traffic Police Each country has differing road rules, including how traffic lights are to be interpreted. For example, in some countries, a flashing yellow light means that a motorist may proceed with care if the road is clear, giving way to pedestrians and to other road vehicles that may have priority (essentially the same as arriving at a non-signalized intersection and not facing a stop sign). A flashing red may be treated as a regular stop sign.

6.2 Turning signals and rules

Figure 6.2 – Working of Traffic Lights

In

some

instances,

traffic

may

turn

left

(in

left-driving

jurisdictions) or right (in right-driving jurisdictions) after stopping at a red light, providing they give way to the pedestrians and other vehicles. In some cases which generally disallow this, a sign next to the traffic light indicates that it is allowed at a particular intersection. Conversely, jurisdictions which generally allow this might forbid it at a particular intersection with a "no turn on red" sign, or might put a green arrow to indicate specifically when a turn is allowed without having to yield to pedestrians (this is usually when traffic from the perpendicular street is making a turn onto one's street and thus no pedestrians are allowed in the intersection anyway).

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Intelligent Ambulance for City Traffic Police Some jurisdictions allow turning on red in the opposite direction (left in right-driving countries; right in left-driving countries) from a oneway road onto another one-way road; some of these even allow these turns from a two-way road onto a one-way road. Also differing is whether a red arrow prohibits turns; some jurisdictions require a "no turn on red" sign in these cases. A study in the State of Illinois (a rightdriving jurisdiction) concluded that allowing drivers to proceed straight on red after stopping, at specially posted T-intersections where the intersecting road went only left, was dangerous. Proceeding straight on red at T-intersections where the intersecting road went only left was once legal in Mainland China with right-hand traffic provided that such movement would not interfere with other traffic, but when the Road Traffic Safety Law of the People's Republic of China took effect on 1 May 2004, such movement was outlawed.[13]. In some other countries the permission is indicated by a flashing amber arrow (cars do not have to stop but must give way to other cars and pedestrians). Another distinction is between intersections that have dedicated signals for turning across the flow of opposing traffic and those that do not. Such signals are called dedicated left-turn lights in the United States and Canada (since opposing traffic is on the left). With dedicated left turn signals, a left-pointing arrow turns green when traffic may turn left without conflict, and turns red or disappears otherwise. Such a signal is referred to as a "protected" signal if it has its own red phase; a "permissive" signal does not have such a feature. Three standard versions of the permissive signal exist: One version is a horizontal bar with five lights - the green and yellow arrows are located between the standard green and yellow lights. A vertical 5-light bar holds the arrows underneath the standard green light (in this arrangement, the yellow arrow is sometimes omitted, leaving only the green arrow below the solid green light, or possibly an LED based device capable of showing both green and yellow arrows within a single lamp housing).

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Intelligent Ambulance for City Traffic Police A third type is known as a "doghouse" or "cluster head" - a vertical column with the two normal lights is on the right side of the signal, a vertical column with the two arrows is located on the left, and the normal red signal is in the middle above the two columns. Cluster signals in Australia and New Zealand use six signals, the sixth being a red arrow which can operate separately from the standard red light. In a fourth type, sometimes seen at intersections in Ontario and Quebec, Canada, there is no dedicated left-turn lamp per se. Instead, the normal green lamp flashes rapidly, indicating permission to go straight as well as make a left turn in front of opposing traffic, which is being held by a steady red lamp. (This "advance green," or flashing green can be somewhat startling and confusing to drivers not familiar with this system. This also can cause confusion amongst visitors to British Columbia, where a flashing green signal denotes a pedestrian controlled intersection.[14]) Another interesting practice seen at least in Ontario is that cars wishing to turn left that arrived after the left turn signal ended can do so during the amber phase, as long as there is enough time to make a safe turn. A flashing amber arrow, which allows drivers to make left turns after giving way to oncoming traffic, is becoming more widespread in the United States, particularly in Oregon. In the normal sequence, a protected green left-turn arrow will first change to a solid amber arrow to indicate the end of the protected phase, then to a flashing amber arrow, which remains flashing until the standard green light changes to amber and red. In Oregon, the amber-flashing arrow is usually housed in a separate light head from the steady amber arrow, in order to provide a visible position change. These generally take the form of four signal heads (green, amber, amber, red). On some newer signals, notably in the city of Bend, the green and flashing amber arrows emanate from the same light head through the use of a dual-color LED array, while the solid amber arrow is mounted above it.

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Generally, a dedicated left-turn signal is illuminated at the beginning of the green phase of the green-yellow-red-green cycle. This allows left-turn traffic, which often consists of just a few cars, to vacate the intersection quickly before giving priority to vehicles traveling straight. This increases the throughput of left-turn traffic while reducing the number of drivers, perhaps frustrated by long waits in heavy traffic for opposing traffic to clear, attempting to make an illegal left turn on red. If there is no left-turn signal, the law requires one to yield to oncoming traffic and turn when the intersection is clear and it is safe to do so. Nevertheless, it is increasingly and disturbingly common in at least the U.S. to see drivers who do not yield in the absence of a dedicated signal, cutting off traffic that has right-of-way and is starting to head across the intersection.[citation needed] In the U.S., many older inner-city and rural areas do not have dedicated left-turn lights, while most newer suburban areas have them. Such lights tend to decrease the overall efficiency of the intersection as it becomes congested, although it makes intersections safer by reducing the risk of head-on collisions and may even speed up through traffic, but if a significant amount of traffic is turning, a dedicated turn signal helps eliminate congestion. Some intersections with protected-turn signals occasionally have what is known as "yellow trap", "lag-trap", or "left turn trap" (in right-driving countries). It occurs at intersections where vehicles are permitted to make left turns on normal green lights. "Yellow trap" refers to situations when left-turning drivers are trapped in the intersection with a red light, while opposing traffic still has a green.

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For example, an intersection has dedicated left-turn signals for traffic traveling north. The southbound traffic gets a red light so northbound traffic can make a left turn, but the straight-through northbound traffic continues to get a green light. A southbound driver who had entered the intersection earlier will now be in a predicament, since they have no idea whether traffic continuing straight for both directions is becoming red, or just their direction. The driver will now have to check the traffic light behind them, which is often impossible from the viewing angle of a driver's seat. This can also happen when emergency vehicles or railroads preempt normal signal operation. In the United States, signs reading "Oncoming traffic has extended green" or "Oncoming traffic may have extended green" must be posted at intersections where the "yellow trap" condition exists. Although motorcycles and scooters in most jurisdictions follow the same traffic signal rules for left turns as do cars and trucks, some places, such as Taiwan, have different rules. In these areas, it is not permitted for such small and often hard-to-see vehicles to turn left in front of oncoming traffic on certain high-volume roads when there is no dedicated left-turn signal. Instead, in order to make a left turn, the rider moves to the right side of the road, travels through the first half of the intersection on green, then slows down and stops directly in front of the line of cars on the driver's right waiting to travel across the intersection, which are of course being held by a red light. There is often a white box painted on the road in this location to indicate where the riders should group. The rider turns the bike 90 degrees to the left from the original direction of travel and proceeds along with the line of cars when the red light turns green, completing the left turn. This procedure improves safety because the rider never has to cross oncoming traffic, which is particularly important given the much greater likelihood of injury when a cycle is hit by a car or truck.

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Intelligent Ambulance for City Traffic Police This system (called a "hook-turn") is also used at many intersections in the CBD of Melbourne, Australia, where both streets carry tramways. This is done so right-turning vehicles (Australia drives on the left) do not block the passage of trams. The system is being extended to the suburbs. At intersections where no turns are allowed from any direction, the green light can be replaced with a green arrow pointing up.

6.3 Programming on LEDs

In 8051 LEDs can be connected to pins P3_0, P3_1, P3_6, and

P3_7. These pins have to be initialized as input ports or out put port. For input initialization port is given as 1 and for out put port is given as 0. Example: Write a program for blinking of an LED #include<P89v51rd2.h> void delay(unsigned char del); void main() { while(1) { P3_0=0; delay (20); P3_0=1; Delay (20); } } void delay (unsigned char del) { int i,j; for (i=0;i<1000;i++) for (j=0;j<del;j++); } Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 44

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7. ADVANTAGES & ISSUE RELATED TO INTELLIGENT AMBULANCE
7.1 Abstract Problem statement- Traffic congestion and tidal
flow management were recognized as major problems in modern urban areas, which have caused much frustration and loss of man-hours. In order to solve the problem an intelligent RFID traffic control has been developed. It is intended to avoid the problems that usually arise with conventional systems.

7.2 Pre-timed- where the signal phases and cycle length are
predetermined using historical data; the time period of green light is predetermined and it continues to be the same throughout the day, if no sensory input is received. In our case the predetermined time for green light is 5 seconds.

7.3 Actuated- where the signal phase lengths are adjusted in
response to traffic flow, as registered by the actuation of vehicle and/or pedestrian detectors; if a sensory output is received by the controller, it adjusts the time period of green light for the next road. Suppose we are using only the output from the sensors then the drawback is that suppose in a low congested road an ambulance or a high priority vehicle comes it will not be signaled unless and until the congestion is avoided so to deal with this situation we are planning to in incorporate RFID modules which will prioritize the signals based on the traffic on the priority vehicles also.

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8. CONCLUSION
A system is useful to improve the traffic flow on the road as well as at the intersections of the roads, which in turn reduce the traveling time, fuel consumption, and emissions, by reducing the cross over time required at each intersection and by preventing or relieving the congestions on the roads. The method controls traffic of vehicles running between the two intersections or signals. The system

establishes the intelligent interaction among every two adjacent traffic signals which results in the helps in the formation of the collection of vehicles crossing the next signal which in tern helps in optimum utilization of the ON time or Green time of the traffic signals. The system also provides the real-time, necessary and useful information to drivers in order to cross the next intersection or signal in minimum time without exceeding or crossing the maximum and the minimum speed limits. The system also detects the vehicle congestions and resolves it by adjusting the traffic flow and size of the vehicle collections, accordingly by changing the ON times of the signals with the help of intelligent interaction among the traffic signals. The ON time of the traffic signal near the congestion area is increased and the increased time helps to resume the traffic flow, as earlier. The increased amount of time is adjusted from the ON time of the adjacent signals so that the traffic flow in the other areas should be less affected.

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11. REFRENCES
 8051 Microcontroller & Embedded Systems using assembly and C Languages. Author : Muhammed Ali Mazidi, Janice Gillispie Mazidi. 2006.  8051 Microcontroller 4th Edition Author : Mc Kenzie  8051 Microcontroller Hardware, Software & Interfacing Author : 1) James W Stewart 2) Kai Z. Mico 1999.  RFID Hand Book: Fundamentals & Applications Author : Klans Finkenzeller 2003. RFID : Radio Frequency Identification Author : Steven Shepherd 2005.  RFID Essentials Author : Bill Glover Himanshu Bhatt 2006.  Sensors & Actuators Author : Elseiver 2001.  Optical Sensors Author : Narayan Swami  Linear and Digital IC Application Author: U.A. Bakshi  Digital Electronics & Logic Design Author : B Somnath Nair Department of Instrumentation Technology Engineering K.B.N. College of Engineering, Gulbarga 47

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WEBSITES:
http://www.Digant.com// http://www.555 Timer tutorials.com// //Wikipedia, the free encyclopedia// http://www.alldata sheets.com// http://www.Luminlabz.com//

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