Project 5 Solution

Design a Parking Meter

In this lab, you will design and implement a finite state machine (FSM) for a parking meter.

Introduction

In this lab, you are required to design an FSM to model a parking meter which simulates coins being added and displays the appropriate time remaining.

System Specifications:

The input buttons represent different coin denominations and the seven-segment LED display will display the time remaining before the meter expires in seconds.

The inputs to the system have been listed in the table below

Inputs
Function


add1
add 60 seconds


add2
add 120 seconds


add3
add 180 seconds


add4
add 300 seconds


rst1
reset time to 16 seconds


rst2
reset time to 150 seconds


clk
frequency of 100 Hz


rst
resets to the initial state





As soon as a button is pushed, the time should be added immediately. The output is modelled as 4 seven segment displays which display the time remaining.
Students will be notified via CCLE if any changes are made.




    • In the initial state, the seven-segment displays should be flashing 0000 with period 1 sec and duty cycle 50% (on for 0.5 sec and off for 0.5 sec).

    • When any add button (add0, add1, add2 or add3) is pressed, the display adds to the corresponding time and starts counting down.

    • When less than 180 seconds remain, the display should flash with a period of 2 seconds and 50% duty cycle. You should have alternate counts on the display like

180, blank,178, blank,176,…). Make sure you blink such that even values show up and odd values are blanked out.

    • When the time has expired, the display should flash 0000 with period 1 sec and duty cycle 50% (on for 0.5 sec and off for 0.5 sec).

    • For example, if add4 is then pushed, the display should read 300 seconds and begin counting down (at 1 Hz). When the timer counts down to 180 seconds and add2 is pushed, the display should then read 400 seconds (120 + 180) and continue counting down. If rst1 goes high, then the display gets reset to 15 seconds and starts flashing accordingly while counting down.

    • The max value of time will be 9999 and any attempt to increment beyond 9999, should result in the counter latching to 9999 and counting down from there.

    • Use input clock(clk) frequency as 100 Hz

    • Include a global input reset (rst) which takes the FSM to the initial state.

    • Do not account for multiple inputs being pressed at the same time.





Though you do not have access to the FPGA, you will be required to design the output module which displays the time on the 4 seven segment displays for full credit.

The output module consists of a seven-segment vector led_seg which displays the actual value fed to the 4 segments corresponding to the digits being displayed. The order of the mapping is from CA to CG with CA being the most significant bit. (refer the link below)

The anodes driving each of these segments are (one bit signals) a1,a2,a3,a4. Please refer to the Xilinx Nexys 3 reference manual to design the seven segment display module. You will need to multiplex the seven segment displays with the anodes as would be required in actual hardware.

https://reference.digilentinc.com/reference/programmable-logic/nexys-3/reference-manual



Include 4 other output ports (val1, val2, val3, val4) which display the actual digit in BCD (binary coded decimal) corresponding to each of the segments. You will be given partial credit for these ports even if your seven-segment implementation is not accurate.
Students will be notified via CCLE if any changes are made.







Deliverables

When you finish, the following should be submitted for this lab:


    1. Verilog source code for the “parking_meter” module. The file should be named exactly as “parking_meter.v” and the port names should exactly match names defined in the design description. If you are using sub-modules, define them within parking_meter.v. Please DO NOT submit them as separate files.

    2. Verilog testbench you used to evaluate your design. Note that your testbench is graded based on the correctness of the waveforms generated in your report.

Please name the file “testbench_UID.v” where UID is your UCLA ID. Make sure you test all the special cases.

    3. Lab Report: Please refer to the syllabus for the basic components of your lab report. (Introduction and (~10%) Design description (~15%), Simulation documentation (~10%), Conclusion (~5%)). Note:

        1. Include the FSM diagram and explain the states and transitions of your FSM.
        2. Explain how you test your design and include simulation waveforms

        3. Schematics can be generated from ISE but please explain how your Verilog code results in the RTL generated. Include the ‘Design Summary’ section of the synthesis report and the summary of your implementation (map) report and write 1-2 lines on the conclusions you draw from these reports. requirement

        4. Please name your report “Firstname_Lastname_Project5_UID.pdf” where UID is your UCLA ID.
    4. Video: Please refer to ‘Syllabus’ for details.

Submission Checklist :
    • Please submit ONLY the files in this table
    • There is no late submission for this project.

    • It is recommended that you have your submission ready an hour or two before the deadline so that you do not face problems due to long upload times etc.


Type
SUBMIT THESE FILES
Contents



Report
Firstname_Lastname_Project5_UID.pdf
-



Design

parking_meter.v



Students will be notified via CCLE if any changes are made.


Testbench
Firstname_Lastname_Project5_codes.zip
testbench_UID.v






Video
Firstname_Lastname_Project5_video.zip
video_UID.()


(extension : some video format -





ex. mp4)