Ch3_Solutions_WAM2.2

Ch3_Solutions_WAM2.2 - What's a Microcontroller? - Chapter...

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What’s a Microcontroller? - Chapter 3 Homework Solutions Chapter 3 Questions 1. What are the warning signs that indicate you might have made a serious mistake while wiring your circuit? If you were using the Board of Education, if the PwrLED goes dim or goes out completely when you plug in the power supply, it means you have a short circuit, and need to disconnect power and correct the circuit immediately. 2. What two states can a pushbutton circuit be in? What numbers does the BASIC Stamp use for each of these states? The two states are either an open loop or a closed loop. The Basic Stamp uses a 0 for an open loop and a 1 for a closed loop. 3. What does a BASIC Stamp I/O pin set to input see when a normally open pushbutton circuit that uses a pull-down resistor is pressed? What does it see when the pushbutton is not pressed? When the pushbutton is pressed it senses that Vdd is connected to the I/O pin. If the pushbutton is not pressed, the BASIC Stamp cannot sense Vdd, but it can sense Vss. 4. When does current flow through a pushbutton circuit with a normally open pushbutton? Current flows through a normally open pushbutton circuit when the button is pressed. 5. What is the difference between a pull-up and pull-down resistor? A pull-down resistor pulls the voltage at the I/O pin down to Vss (0 volts) when the button is not pressed. A pull-up resistor pulls the voltage up to Vdd (5 volts) when the button is not pressed. For the pull-up resistor, the IN3 stores a 1 when the button is not pressed and a 0 when it is pressed (opposite of a pull-down resistor). 6. If you modify a pushbutton circuit that used to use a pull-down resistor so that it uses a pull-up resistor, do you expect to see changes in the values at the I/O pin? Yes, for the pull-down resistor, the IN3 stores a 0 when the button is not pressed,
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This note was uploaded on 07/25/2008 for the course ME 456 taught by Professor Radcliffe during the Fall '07 term at Michigan State University.

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Ch3_Solutions_WAM2.2 - What's a Microcontroller? - Chapter...

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