aLec09_switch_LED - Introduction to Embedded Microcomputer...

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Introduction to Embedded Microcomputer Systems Lecture 9.1 Jonathan W. Valvano Recap Addition and subtraction set CCR bits Subtraction used for conditional branching Overview Switch interfacing LED interfacing Introduction to Lab 2 Running on the real 9S12 board if-then statements reviewed Input Port Computer Output +5V 1k Ω V 1 33 μ F 74LS14 22 Ω +5V 10k Ω Input Pin pressed 0V low released 5V high +5V 10k Ω Input Pin pressed 0V low released 5V high Show actual switch interface and voltages with the DVM LED interfacing I V 2V 10mA LED brightness = power = V*I Photo: Circuit symbol: LEDs emit light when an electric current passes through them. LEDs have polarity, meaning current must pass from anode to cathode to activate. The anode is labeled a or + , and cathode is labeled k or - . The cathode is the short lead and there may be a slight flat spot on the body of round LEDs. Thus, the anode is the longer lead LED interfacing 250 Ω +5V 7405 LED Microcomputer Output Port high +5V low +0.5V I = = 10mA 5-2-0.5V 250 Ω low 0.5V off, HiZ I = 0, LED is dark
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This note was uploaded on 09/19/2010 for the course E E 16280 taught by Professor Valvano during the Fall '10 term at University of Texas at Austin.

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aLec09_switch_LED - Introduction to Embedded Microcomputer...

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