1. EE 316 Computer Engineering Junior Lab Project 1: Traffic Light Controller

2. The traffic Light Controller Source: John Wakerly

3. Specifications EW street is heavily traveled NW street is lightly traveled Pedestrian can halt traffic for crossing but not create traffic jam EW, NS and Pedestrian traffic signals have at least Green and Red lights Each green light is on for 5, 9 and 4 secs, respectively

4. Remember! The design cycle involves:  Careful planning  Learning  Setting specific goals  Designing  Building  Testing and  Troubleshooting

5. Design Methodology Study the details in the Specification (read between lines). Partition the design problem into smaller sub-components or parts. Create specifications for each part and their interactions with others. Design and build each of the basic components/parts and test them thoroughly before attempting to combine with or connect to other sub- components. Predict what to expect at each step and decide how would you test your hypothesis with measurements.

6. Design Methodology (contd.) Test the circuit and verify if your design worked as expected Troubleshoot your circuit if design does not work. Pay attention to power/ground lines, interfaces/ports (pin diagram and wires), fanout, drive currents (TTL vs. CMOS), bad connections, wrong delays etc. Modify the design if needs and repeat the steps. Write every step in the Notebook (legible documentation please). Draw circuit diagrams, pin diagrams chips, test and measurement results, troubleshooting, and design changes etc.

7. A partial list of subcomponents A state machine (sequential circuit) Counter/timer Clock generator circuit 7-segment displays LEDs to be used as traffic signals PC and XP compatible software

8. The state machine and the controller State diagram/table and outputs State assignment and K-maps A timer/counter to be used as a controller to trigger transition from one state to the other depending on the inputs

9. Counter/Timer and clock generation circuit Identify a TTL or CMOS based 7400 series chip that would be appropriate for this project Study the data sheet carefully before using any chip Verify the clock frequency with an oscilloscope. Use the digital logic analyzer to verify design

10. 7-Segment Displays and LEDs You will need appropriate Drivers for the two kinds Of displays. Also, remember LEDs/displays can be destroyed very easily. Use resistors to limit current http://www.play-hookey.com/digital/experiments/seven_seg_led.html

11. More details Add bypass capacitors between VDD and GND if you cannot explain state skips or strange behaviors.

12. The IEEE 1284 parallel interface standard Parallel ports are used for connecting a computer (host) to a printer or certain other peripheral devices over a parallel (eight bits of data at a time) physical and electrical interface. Parallel ports conform to the specifications of document of the Institute of Electrical and Electronic Engineers (IEEE) called IEEE Std 1284-1994: Standard Signaling Method for a Bi-directional Parallel Peripheral Interface for Personal Computers, or IEEE 1284 for short. http://whatis.techtarget.com/definition/0,,sid9_gci213469,00.html http://www.lavalink.com/fileadmin/white_papers/ieee1284_parallel_ports.pdf

13. Modes of operation (The IEEE 1284 standard) Compatibility mode (Default “Forward” mode) Nibble mode (4-bit “reverse” mode) Byte mode (8-bit “reverse” mode) EPP mode (Enhanced Parallel Port mode) ECP mode (Enhanced Capability Port mode) Source: http://www.lvr.com/files/ppc1.pdfhttp://www.lvr.com/files/ppc1.pdf Forward: Host to Peripheral Reverse: Peripheral to Host

14. 25 Pin D-sub or IEEE 1284-A connectors http://www.lavalink.com/fileadmin/white_papers/ieee1284_parallel_ports.pdf

15. 36 Pin Centronics or IEEE 1284-B connectors http://www.lavalink.com/fileadmin/white_papers/ieee1284_parallel_ports.pdf

16. IEEE-1284 compliant Parallel Printer Cables Connector Types IEEE-1284 Printer Type “A” Connector (DB25) This is the connector most commonly used as the computers parallel port output. IEEE-1284 Printer Type “B” Connector (CN36) This is the most commonly used connector for the end of the cable that goes to the printer. IEEE-1284 Printer Type “C” Connector (HPCN36) This is a new connector for the printer end of the cable. http://www.ramelectronics.net/html/ieee-1284_printer_cables.html

17. DB-25 Female D-type Connector (on the computer) http://www.doc.ic.ac.uk/~ih/doc/par/index.html#index 8 output pins accessed via the DATA Port (bidirectional) 5 input pins (one inverted) accessed via the STATUS Port (peripheral to HOST) 4 output pins (three inverted) accessed via the CONTROL Port (output only) The remaining 8 pins are grounded

19. Addressing Standard parallel port uses three contiguous addresses: 3BCh, 3BDh, 3BEh (LPT1) 378h, 379h, 37Ah (LPT1, LPT2) 278h, 279h, 27Ah (LPT1, LPT2, LPT3)) First Address -- Port base address (data registers) Second Address -- (base+1) Port’s status registers Third Address – (base+2) Ports Control Registers In our lab we have a PCI parallel card that uses the Following address: DF18h, DF19h, DF1Ah

20. Parallel port output drive capabilities http://www.hut.fi/Misc/Electronics/circuits/lptpower.html The outputs of the data registers are filtered through A 27 Ohm resistor and a 2.2 nF capacitors. The numbers can vary substantially between different port types. For fast transitions and more drive currents it is best to use Schmitt-trigger buffers/inverters at the receiving end.

21. Project Reports Each project writer is to submit a project report containing: Summary (Executive summary or abstract) Design Problem Statement Problem Decomposition Significant details of design process Alternative designs Design Documentation Schematics documenting your hardware design HDL and test bench files (for future reports Software design, i.e. flowchart or pseudocode Testing: Module level testing Specification testing Performance Results and Analysis References

22. References http://www.lvr.com/files/ppc1.pdf http://whatis.techtarget.com/definition/0,,sid9_gci213469,00.html http://www.doc.ic.ac.uk/~ih/doc/par/index.html#index http://www.epanorama.net/circuits/parallel_output.html http://www.hut.fi/Misc/Electronics/circuits/lptpower.html