Encoding and Decoding of Digital Signals - Lab Assignment #2 | EECS 203, Lab Reports of Discrete Mathematics

Download Encoding and Decoding of Digital Signals - Lab Assignment #2 | EECS 203 and more Lab Reports Discrete Mathematics in PDF only on Docsity! Encoding and Decoding of Digital Signals Laboratory assignment two ECE 203 Prepared by Robert Dick Lab report due during your lab check slot on 16 April Please keep track of how long you spend doing this laboratory assignment. Specifically, how much time is needed to do the problems after studying enough to understand the concepts? Please carefully review lecture four before starting this assignment. If you make catastrophic wiring mistakes, this could result in be exploding integrated circuits sending chunks of plastic into your forehead. In this laboratory assignment, you will be implementing two circuits. The first will encode signals for transmission through fewer communication wires. The second will decode the signal. Please show your work in your lab report. For example, if you do algebraic simplification, show your steps. Don’t unwire this lab when you’re done. You’ll need to use it as a starting point for your next assignment! Please make your design compact. It will make the next assignment easier. 1 Background You have been hired by a space flight company to design an orbital rocket control system. An actuator is a device which performs a mechanical action in response to an input signal. Most of actuator signals for the rocket generated by error-tolerant primary control computers located very near the actuators. However, a few signals must come from the pilot control panel. The pilot should be able to push buttons to generate any of the following signals: “open hatch,” “decompress cabin,” “release safety harness,” and “eject pilot”. 2 Design change Initially, it seemed wise to use a heavily shielded cable with separate wire for each of the lines, for a total of four wires. However, after the rocket was built, the design team decided to add a “self-destruct” button for use by the pilot in case the rocket was on course toward a populated area during takeoff or landing. There is a time delay associated with the self-destruct signal, giving enough time to press the “eject pilot” button before it takes effect. 3 Backward compatability Unfortunately, the addition of a new signal complicates transmission from the pilot control panel to the actuators. A number of other devices have been built around the control signal cable – replacing it with a cable composed of five wires would take a huge amount of time. Instead, your team suggests encoding the button information so that it requires fewer bits. 1 4 Redesign: Encoder Given that only one button will be pressed at a time, the following six conditions must be representable: 1. no action 2. open hatch (H) 3. decompress cabin (C) 4. eject pilot (P ) 5. release safety harness (S) 6. self-destruct (D) Determine a way to encode these five conditions using only three bits of information, i.e., assign a three-bit binary number to each of the five conditions. By using three bits, you will require only three of the four wires in the existing cable. For each of the three encoded signal wires (J, K, and L), find a function of the inputs (H,C, P, S, and D). Implement these functions using whichever gates are most convenient. For example, if one had only two input buttons, A and B, and three codes carried on two signal wires (J and K), the following encodings could be used: Input Code (JK) none 00 A 01 B 11 In this case, J = B and K = A + B. In other words, you can build your circuit with Or gates. Recall that you can build three-input Or gates from two-input Or gates, i.e., A + B + C = (A + B) + C. This implementation is your input circuit. It will consist of five input switches, some logic gates to implement the encoding, and three output signals connected to LEDs. You can leave off the display LEDs on the inputs, but not on the J, K, and L, or the outputs. Don’t omit the 510 Ω pull-down resistors on the inputs. 2