Four way traffic light conrol using Verilog
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This presentation summarizes the history and development of traffic lights. It discusses how the first traffic light was installed in London in 1868 [1]. It then provides details on the typical light sequences of red, yellow, and green [2]. The presentation goes on to describe how a basic four-way traffic light system can be modeled using a state diagram and Verilog code [3]. It concludes by discussing how more advanced traffic light controllers can help improve urban traffic flow.
Four way traffic light conrol using Verilog
- 1. PRESENTATION BY:- ASHUTOSH SHARMA UTKARSH DE SHRAWAN RAWAT LALIT KUMAR SHUBHAM SHARMA
- 2. INTRODUCTION TRAFFIC LIGHTS HISTORY VERILOG FOUR WAY TLC TRAFFIC LIGHT STATE DIAGRAM OUR TRAFFIC LIGHT STATE TABLE STATE DIAGRAM WAVEFORM CODING OVERVIEW FUTURE SCOPE CONCLUSION
- 3. HISTORY Traffic light which is one of the vital public facilities that plays an important role to the road users. Traffic lights were first installed in 1868 in London, United Kingdom, outside the British Houses of Parliament in London, by the railway engineer J. P. Knight and constructed by the railway signal engineers of Saxby & Farmer.
- 4. The design combined three semaphore arms with red and green gas lamps for night-time use, on a pillar, operated by a police constable. The gas lantern was turned with a lever at its base so that the appropriate light faced traffic. Although it was said to be successful at controlling traffic, its operational life was brief. It exploded on 2 January 1869, as a result of a leak in one of the gas lines underneath the pavement, injuring and killing the policeman who was operating it. With doubts about its safety, the concept was abandoned until electric signals became available .
- 5. Traffic lights, also known as traffic signals, traffic lamps, signal lights, stop lights and also known technically as traffic control signals are signalling devices positioned at road intersections, pedestrian crossings and other locations to control competing flows of traffic.
- 6. Traffic lights alternate the right of way accorded to road users by displaying lights of a standard color (red, yellow, and green) following a universal color code. The typical sequence of color phases are as follows:
- 7. GREEN:- Allows traffic to proceed in the direction denoted. YELLOW:- Provides warning that the signal will be changing from green to red. RED:- Prohibits any traffic from proceeding.
- 8. 1. Safe and efficient traffic light flow 2. Assign right of way to maximize capacity, minimize and reduce collision and conflict
- 9. Verilog HDL is one of the two most common Hardware Description Languages (HDL) used by integrated circuit (IC) designers. The other one is VHDL. HDL’s allows the design to be simulated earlier in the design cycle in order to correct errors or experiment with different architectures. Designs described in HDL are technology-independent, easy to design and debug, and are
- 10. usually more readable than schematics, particularly for large circuits. Verilog can be used to describe designs at four levels of abstraction: (i) Algorithmic level (much like c code with if, case and loop statements). (ii) Register transfer level (RTL uses registers connected by Boolean equations). (iii) Gate level (interconnected AND, NOR etc.). (iv) Switch level (the switches are MOS transistors inside gates).
- 11. It is often useful to be able to sequence through an arbitrary number of states , staying in each state an arbitrary amount of time. Consider the set of traffic lights shown in Figure.
- 13. The lights are assumed to be at a four-way intersection with one street going north-south and the other road going east-west.
- 15. To simulate these traffic lights we will use the red, yellow, and green LEDs which cycle through the six states shown in Table .
- 17. A state diagram for controlling these traffic lights is shown in Fig.
- 19. If we use a 3 Hz clock to drive this state diagram then a delay of 1 second is achieved by staying in a state for three clock cycles. Similarly, a delay of 5 second is achieved by staying in a state for fifteen clock cycles.
- 20. The count variable in fig will be reset to zero when moving to the next state after a timeout.
- 21. case(state) S0: if(count < SEC5) ◦ begin state <= S0; count <= count + 1; ◦ end
- 22. else ◦ begin state <= S1; count <= 0; ◦ end
- 23. S1: if(count < SEC1) ◦ begin state <= S1; count <= count + 1; ◦ end
- 24. else ◦ begin state <= S2; count <= 0; ◦ end
- 25. :
- 26. Development of Software of Intelligent Traffic Light Control and Monitoring System : Assembler Assembler is used to convert the assembly language code to machine code. A51 assembler is used for this purpose. Following Figure shows the A51 assembler GUI.
- 28. The modern ways of multi-way traffic management improves the traffic condition up to a large extent. Advanced signaling controllers contribute to the improvement of the urban traffic which is proportional to the complexity of the controller. These more complex controllers can be well handled using states machines. Methods to reduce the states in the state machine also help in reducing the required hardware
- 29. leading to low power and area efficient design. In addition to the general procedure the Chip Scope Pro & VIO of Xilinx tool gives the flexibility in verification for the design with large number of inputs & outputs, also used for easy implementation of the design into the FPGA.