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Traffic control system // digital design and implementation

In spring of '07, I took a digital electronics class in which our final project was to design and implement a traffic control system on a CPLD using VHDL. I was the team leader for our group of three, and really enjoyed working on this project - going above and beyond the requirements. I was responsible for the physical implementation and construction, and I also designed most of the circuitry. I ended up building the circuit board, as well as debugging and rewriting most of the code.

Requirements:
• design of traffic controller on a CPLD development board
• two-lane thoroughfare with left turn lane, intersected by small crossroad
• implementation on a small model

Additional Features:
• light sensors to trigger when cars were waiting in the turn lane or cross street
• 7-segment LED displays to demonstrate timing sequences
• robust logic to optimize traffic flow
• self-contained scale model with all circuitry inside and simple user interface
• idle mode, to pause execution while explaining each state of its cycle

I won't go into much detail on this one, but here are some pictures of our model.

[p digital_1.jpg Model intersection in action][p digital_2.jpg Our completed project][p digital_3.jpg The display and sensor circuity to interface with the CPLD][p digital_4.jpg A traffic light][p digital_5.jpg Lights for the two straight lanes, and the left turn][p digital_6.jpg LED displays, sensor activity light/calibration knob, power/idle switch][p digital_7.jpg The underside][p digital_8.jpg The soldering of our circuit board][p digital_9.jpg A look inside the finished project]

And here is some of the code, developed in Xilinx ISE.

[p digital_code_1.jpg VHDL segment that controlled the internal timing][p digital_code_2.jpg The state machine that controlled the flow of the cycles][p digital_code_3.jpg Schematic of the CPLD in/outs and connections with our code blocks][p digital_schematic.jpg The light sensor interface circuit]

Our team ended up winning best design in our class (of about 10 teams), and our system is now on display in the engineering department.
curly

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