TRAFFIC SIGNAL CONTROL SYSTEM BASED ON WIRELESS TECHNOLOGY
CONTENTS
The growing vehicle population in all developing and developed countries calls for a major change in the existing traffic signaling systems. The most widely used automated system uses simple timer based operation which is inefficient for non-uniform traffic. Advanced automated systems in testing use image processing techniques or advanced communication systems in vehicles to communicate with signals and ask for routing. This might not be implementable in developing countries as they prove to be complex and expensive. The concept proposed in this paper involves use of wireless sensor networks to sense presence of traffic near junctions and hence route the traffic based on traffic density in the desired direction. This system does not require any system in vehicles so can be implemented in any traffic system easily. This system uses wireless sensor networks technology to sense vehicles and a microcontroller based routing algorithm for traffic management.
Introduction
Block diagram
Microcontroller in embedded systems
We want to have systems that :
● are reliable
● are small and lightweight
● have a low power consumption
These issues are critical when we deal with body implants
Some features / advantages of microcontrollers:
● they are small and flexible
● easy to use ( most of the time .. )
● few external components and wires needed
● low and ultra low power designs possible (-> PSoC, ASIC )
● wide range of different uCs available
(memory, I/O, speed, busses, A/Ds )
● data interchange using standard bus systems;
-> various peripheral hardware accessible
● IDEs and tool chains for firmware programming /
● Simulation and high level languages
-> 90% of the manufactured CPUs are not found in desktop PCs but in embedded systems, with growing areas of application: RFID, hidden "ubiquitous" computing, wearables, "smart environments", MEMS (micro electro-mechanical systems)
LPC2148
LPC2148 - RISC Architecture
● 130 Instructions – Most Single-clock Cycle Execution
● 32 x 8 General Purpose Working Registers
● 64 x 8 Special Function Registers (I/O Registers)
● Up to 16 MIPS Throughput at 16 MHz
● On-chip 2-cycle Multiplier
Nonvolatile Program and Data Memories
● 8K Bytes of In-System Self-Programmable Flash
10,000 Write/Erase Cycles
● Optional Boot Code Section with Independent Lock Bits
● 512 Bytes EEPROM (100,000 Write/Erase Cycles)
● 1K Byte Internal SRAM
● Programming Lock for Software Security
Peripheral Features
● Two 8-bit Timer/Counters
● One 16-bit Timer/Counter with Capture Mode
● Real Time Counter with Separate Oscillator
● Three PWM Channels
● 6-channel ADC with 10 resp 8 Bit resolution (TQFP: 8 channels)
● Two-wire Serial Interface (TWI)
● Programmable Serial USART
● Master/Slave SPI Serial Interface
● Programmable Watchdog Timer with On-chip Oscillator
● On-chip Analog Comparator
Special Microcontroller Features
● Programmable Brown-out Detection
● Internal Calibrated RC Oscillator
● External and Internal Interrupt Sources
● Five Sleep Modes
I/O and Packages
● 23 Programmable I/O Lines
● 28-lead PDIP, 32-lead TQFP, and 32-pad MLF
Operating Voltages
● 2.7 - 5.5V (LPC2148L)
● 4.5 - 5.5V (LPC2148)
Speed Grades
● 0 - 8 MHz (LPC2148L)
● 0 - 16 MHz (LPC2148)
Power Consumption at 4 Mhz, 3V, 25°C
● Active: 3.6 mA
● Idle Mode: 1.0 mA
● Power-down Mode: 0.5 μA
Harvard architecture
● Separate storage and signal pathways for � instructions and data.
● History: Harvard Mark I
relay-based computer
● word width, timing, and implementation � technology of instruction and data memories � can differ.
● Contrast: ‘Von Neumann’ - architecture: � Instructions and data use the same signal � pathways and memory.
Harvard architecture
● Separate storage and signal pathways for � instructions and data.
● History: Harvard Mark I
relay-based computer
● word width, timing, and implementation � technology of instruction and data memories � can differ.
● Contrast: ‘Von Neumann’ - architecture: � Instructions and data use the same signal � pathways and memory.
RF
REMOTE SECTION
RECEIVER SECTION
PIN DIAGRAM OF TRANMITTER AND RECEIVER:
IC HT12E:
HT12E is an encoder integrated circuit of 2^12 series of encoders. They are paired with 2^12 series of decoders for use in remote control system applications. It is mainly used in interfacing RF and infrared circuits. The chosen pair of encoder/decoder should have same number of addresses and data format.
IC HT12D:
HT12D is a decoder integrated circuit that belongs to 212 series of decoders. This series of decoders are mainly used for remote control system applications, like burglar alarm, car door controller, security system etc. It is mainly provided to interface RF and infrared circuits. They are paired with 212 series of encoders. The chosen pair of encoder/decoder should have same number of addresses and data format.
Power supply
The input to the circuit is applied from the regulated power supply. The a.c. input i.e., 230V from the mains supply is step down by the transformer to 12V and is fed to a rectifier. The output obtained from the rectifier is a pulsating d.c voltage. So in order to get a pure d.c voltage, the output voltage from the rectifier is fed to a filter to remove any a.c components present even after rectification. Now, this voltage is given to a voltage regulator to obtain a pure constant dc voltage.