Question

Find the functionality and function table for the given question which is basically the traffic light controller for a dld square

Answer 1

Title: Traffic light controller functionality and function table.

Introduction: The traffic problem is crucial in recent days ,can be solved at road crossings or junctions is controlled by switching ON or OFF Red, Green & Amber lights in a particular sequence.

            The traffic light controller is designed to generate a sequence of digital data called switching sequences that can be used to control the traffic lights of a typical four roads junction in a fixed sequence for all the day.

              It is a sequential machine to be analysed and programmed through a multistep process. The device that involves an analysis of existing sequential machines in traffic lights controllers, timing and synchronization and introduction of operation and flashing light synthesis sequence.

          The methods that are used in this project are designing the circuit with model, simulation, synthesis and implementation of hardware. For modelling and implementation XILINX ISE and VIVADO 2016.1 tools can be used..even one can use another variety of tools also.]

            Traffic jamming is a critical predicament in many of the cities and towns all over the world .Traffic congestion has been causing many setbacks and challenges in the major and most occupied cities all over the globe. To travel within the cities to the place of work or recreation has become a big problem to the commutates all along. Due to these problems people lose time, money and most importantly the energy resources will be exhausted due to the continual use in the automobiles.

            This traffic jam directly impacts the productivity of the workers, traders, suppliers and in all effecting the market and raising the prices of the commodities in a way. To solve these traffic related problems, we have to build new conveniences, infrastructure but at the same time make it smart. The only drawback of making new roads on facilities is that it makes the surroundings more congested, but then this will make a way to have new ways to ease the traffic. Perhaps all the countries are working to accommodate the traffic flow and advance transportation and reduce the demand of vehicle use.

Preferred FSM for functionality and function table as a part of DLD square

:           FSM stands for Finite state machine it is a model of computation used to design sequential logic circuits. It is an abstract model of machine that can be in one of the finite number of states at a time. The state at any given time is called the current state. A particular FSM is given by a set of states and the triggering condition for each transition .In these, the hardware gets reduced as the whole algorithm can be explained in one process

           

            There are mainly two types of machines-Mealy and Moore. We are using the mealy machine model in which the output depends on the present state as well as the input.

Types of State Machines:

• Two types of state machines are in general use, namely

(i) Moore machines and

(ii) Mealy machines

• In this course we will only look in detail at FSM design using Moore machines, although for completeness we will briefly describe the structure of Mealy machines.

Mealy machine:

• It is a Sequential system where output depends on current input and state.

Moore machine:

•Sequential system where output depends only on current state.

Functionality:

• Traffic signals control vehicle and pedestrian traffic by assigning priorities to various traffic movements to influence traffic flow.
• It increases traffic- handling capacity of an intersection and it provides continuous movement of traffic at a definite speed along a given route.
• Interrupt heavy traffic at intervals to permit other vehicles or pedestrians to cross.
• Traffic light controller can be operated in different types of modes. Fixed-time mode and Actual mode.
• In Fixed- time mode, signals follow a predetermined sequence of signal operation
• In Actual mode, signals change the lights according to the amount of traffic in each direction.
• In this Traffic light controller consists of three outputs, namely Red, Green and Yellow Lights and one input which is a clock signal.
• The working of this system is explained as follows:
• Initially we give a continuous clock input to the system.
• In this condition, the Red light will be ON , then after a fixed amount of delay provided by the system the clock signal is operated at low level( clock = 0 ) then the Red light is going to be in OFF state.
• when ever the clock pulse signal is going to be High, then the present output changes from Red to Green.
• Similarly, the yellow light can be turned ON , again when the clock signal is made to be High.

Function table: