Exercise 1: Introduction to Digital Circuits EE214 Fall 2014

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1 Exercise 1: Introduction to Digital Circuits EE214 Fall 2014 I am submitting my own work in this exercise, and I am aware of the penalties for cheating that will be assessed if I submit work for credit that is not my own. Print Name GRADER # Points Score T 75 Sign Name Date Problem 1. (15 points) Below are some circuit elements from a simple digital system. 3.3V SW1 R A 1Kohm V A 1.3V R B V B 20mA V C SW2 R C 1K R D When the pushbutton SW1 is not pressed, what is the voltage at V A? When the SW1 is pressed, what is the voltage at V A? When the SW1 is pressed, what current flows in the 1K resistor R A? When SW1 is pressed, what power is dissipated in R A? In the LED circuit, 1.3V is required at V B to forward-bias the LED and cause current to flow. Given there is a 1.3V drop across the LED, what resistance R B is required for 20mA to flow through the LED? What power is dissipated in the LED? In the circuit on the far right, if R C dissipates 25mW, what is V C? Using the V C voltage you calculated, if R C is changed to 100Ohms, how much power would it dissipate? Using the V C voltage you calculated and a 1K R C, if pressing SW2 causes the total circuit power to increase to 75mW, what value must R D be? (3pt) Contains material Digilent, Inc. 7 pages

2 Problem 2: (20 points) Obtain and read the board s reference manual, paying close attention to the Power Supply and Configuration Sections. Answer the following. Which board are you using: Basys2 Nexys2 Nexys3 Nexys4 How many user LEDs are on the board? (user LEDs are controlled by the main chip) Are these LEDs illuminated with a logic 1 or logic 0? How many pushbuttons on the board? Do the pushbuttons output logic 1 or 0 when pressed? How many slide-switches on board? Do the slide switches output constant logic levels (yes or no)? Name the signals that turn on the 7-seg displays: What jumper is used to select USB power? About how much current will your board use from the 5V rail under normal conditions? About how much power will your board use under normal conditions? About how much energy will your board use in one hour? How much current is available to your board over the USB port? What voltage is delivered to your board by the USB port? What range of main input voltage can your board use? Min: Max:

3 Problem 3: (33 points) Find the schematic for your board, and identify the following components both in the schematic and in the photos below. Circle and label the components in the picture, and provide the schematic page number and grid location in the table below (schematic pages have a number/letter grid, with numbers across the top and bottom and letters on the left at right). You only need to complete the section for the board you are using. Basys2 1 Pushbutton number 2 3 PS/2 Port 5 Platform Flash ROM 6 Oscillator: MCLK ; 10 Capacitor C30 Cap value: 11 Resistor R56 Resistor value:

4 Nexys2 1 Pushbutton number 2 3 PS/2 Port 5 Platform Flash ROM 6 Oscillator GCLK0 10 Capacitor C102 Cap value: 11 Resistor R11 Resistor value:

5 Nexys3 1 Pushbutton number 2 3 USB HID port 5 Non-volatile serial ROM 6 Oscillator GCLK0 10 Capacitor C200 Cap value: 11 Resistor R84 Resistor value:

6 Nexys4 1 Pushbutton C 3 USB HID port 5 Non-volatile serial ROM 6 Oscillator CLK100MHz 10 Capacitor C17 Cap value: 11 Resistor R145 Resistor value:

7 Problem 4: Perform a basic inspection and test of the board. Inspect the board and note any components that appear to be missing, damaged, or otherwise compromised. When inspecting the board, you can compare it to the picture on the Digilent website (or the picture in this document). Set the programming mode jumper(s) to configure the board from the on-board ROM. Apply power to the board, and ensure the power-on LED illuminates and glows brightly. The automated test, stored in the on-board Flash ROM at manufacturing time, will automatically configure the FPGA with a circuit that can be used to test all circuits. If the automated test does not automatically load, the ROM image may have been overwritten. Obtain the appropriate Board Verification Project from the Digilent website, and re-load the Flash ROM (see the reference manual of Adept). Alternatively, you can use the automated test tab in Adept to configure the board with a test circuit to drive all the on-board devices. (7 points) Complete the check-off sheet below. If any item has been checked N in the table, consult the lab assistant for help in resolving the issue. All required components present (board, programming cable, etc.) Y N Visual inspection reveals no obvious problems Y N Power On LED glows brightly when power supply attached Y N All segments on all seven-segment digits are functional Y N All slide switches function correctly by illuminating/extinguishing LEDs Y N All LED s illuminate properly Y N All pushbuttons function correctly Y N