lab4_s12_IO_port_keypad

lab4_s12_IO_port_keypad - University of Florida Electrical...

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University of Florida EEL 4744 – Spring 2012 Dr. Eric M. Schwartz Electrical & Computer Engineering Dept. Revision 0 Colin Watson and Ali Nuhi, TAs Page 1/5 Lab 4: Keypad and I/O Port Expansions 15-Feb-12 OBJECTIVES To explore and understand the implementation of memory-mapped I/O. Add an 8-bit input port and an 8-bit output port. To understand how a keypad functions as a raster scan input device and to learn how to interface a keypad to a microprocessor. REQUIRED MATERIALS Wire wrap tool, multi-meter, DSP board 1 - 74HC573, 1- 74HC574, 1 keypad, 2 - 0.1 F bypass capacitors, wire wrap Read/save the following document: o Timing diagram on SPRU949D (pg 33-36) o GPIO Multiplexing and PCLKCR3 description, in SPRUFB0D o Spec sheets for 74HC573 and 74HC574 Helpful Materials: 2 - 20-pin wire wrap sockets for 74HC573 and 74HC574 o Digi-Key part # ED4320-ND. 1 – 10-pin socket ( NOT for wire wrap) for keypad o A wire wrap socket would be better if you can find one o Digi-Key part # A24816-ND PRELAB REQUIREMENTS It is required that you make a flowchart or write pseudo- code before writing any program in this course. This will help you formulate a plan of attack for the code. Submit these flowcharts/pseudo-code as part of your prelab requirements. Comments in your programs are also required. The Pre- lab Report Guidelines state that “All code should be commented to a level that someone how can readily understand the purpose of each section if not each line of code.” Part A: Input/Output Ports, General Description The DSP and other many other microprocessors have several input/output (I/O) pins, often with multiple pins grouped together and called input/output ports. Each of the I/O pins typically has additional non-I/O features that can be utilized as an alternative to general I/O. Therefore, it would be useful if we can “free up” these pins for their special use by adding other memory-mapped I/O ports. 1. Generate the necessary chip-enable equations to implement one 8-bit input port and one 8-bit output port. Both ports should both be mapped to address 0x4800 and mirrored at addresses 0x4801 through 0x4FFF. (For this lab ONLY , ignore address pins A21 through A16. For subsequent labs, we will add other external components that will overlap the addresses specified for the I/O ports unless we include the address pins A21 through A16. Failure to utilize these pins in this case will cause damage to your devices.) Use partial address decoding (also known as reduced-address decoding). Tri-state buffers MUST be used for input ports and flip-flops should be used for output ports (to save output values). Two chips included in your kit, the 74HC573 and 74HC574, contain the tri-state buffers and flip- flops. 2.
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lab4_s12_IO_port_keypad - University of Florida Electrical...

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