lab3_s12_switch_LED_GPIO_loop_LSA - University of Florida...

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University of Florida EEL 4744 – Spring 2012 Dr. Eric M. Schwartz Electrical & Computer Engineering Dept. Revision 3 Erick Macias & Eric Jeffers, TA Page 1/4 Lab 3: Switch Inputs, LED outputs, GPIO, Timing Loop and LSA 13-Feb-12 .OBJECTIVES In this lab you will learn to use the input/output pins on our TI F28335 DSP, called GPIO. You will solder and wirewrap 8 switches (inputs) and 8 LEDs (outputs) to your UF DSP board. For the first time this semester, you will see your programs controlling I/O. You will also learn how to use a logic state analyzer (LSA). REQUIRED MATERIALS UF F28335 DSP board kit and documents from lab 0 through 2 Multimeter YOUR wirewrap tool Access to an LSA (supplied in lab) Read/save the following document: o Lecture 6: GPIO o System Control and Interrupts Reference Guide (TI #: SPRUFB0D) GPIO: Pages 6-68, Section 6 Some of the prelab requirements involve soldering. If you do not own or have access to a soldering iron outside of our 4744 lab, that means that you will need to spend some time prior to your lab at the TA office hours. The TAs will bring a few soldering irons to the TA office hour room in NEB 222. INTRODUCTION Read the entire lab handout before starting! In this first part of the lab you will create an 8-bit LED output circuit connected to GPIO15:8 and an 8-bit switch input circuit connected to GPIO7:0. The active-high LEDs should use series resistors (with the 470 Ohm SIP resistor pack in your lab kit) to limit the current. The switches should be pulled-up to +3.3V (with the 1.2k Ohm SIP resistor pack in your kit). You learned how to build LED and switch circuits in EEL 3701. If you don’t remember, the document at the following website describes how these circuits are constructed: Do not forget to properly set up the GPIO MUX and data direction register and to use the EALLOW instruction near the beginning of your program, in order to allow writes to the GPIO registers. You must also turn off the watchdog timer, or an interrupt will occur almost immediately after you start running your program. Note: IC power and ground should NOT be wirewrapped on printed circuit boards. But in order to allow us to simplify our construction, we will allow it in this course. But, we will expect all IC power and ground signals to have two wirewrap connections. PRELAB REQUIREMENTS Note: Prelab requirements MUST be accomplished PRIOR to coming to your lab. Wirewapping for inexperience engineers may take a significant amount of time; please start early. PART A In this part of the lab you will install an LED output circuit on your PCB. The circuit will be placed as shown in Figure 1. In order to properly orient the LED DIP, you must determine which side has the LED anodes and which has the cathodes. If necessary, use your 3701 breadboard to perform an experiment to determine these positions. Think carefully about how you will orient the DIP LED pack on your PCB. Once the anode/cathode
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lab3_s12_switch_LED_GPIO_loop_LSA - University of Florida...

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