PPI 8255 Programmable I/O Device Quiz
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Questions and Answers

Which type of device is PPI 8255?

  • Power supply unit
  • Microprocessor
  • Memory unit
  • Programmable I/O device (correct)

    • How many 8-bit bidirectional I/O ports does PPI 8255 consist of?

  • Four
  • Three (correct)
  • Two
  • One

    • What is the function of Port C in PPI 8255?

  • It provides power supply to the device
  • It is used for memory storage
  • It acts as a control unit for the device
  • It is further divided into two 4-bit ports and can work in BSR mode or in mode 0 of input-output mode (correct)

    • How many control groups does PPI 8255 have?

    <p>Two (control group A and control group B)</p> Signup and view all the answers

    Which value is used to select different ports in different modes as input-output functions or BSR in PPI 8255?

    <p>CS’, A1, A0</p> Signup and view all the answers

    What is the mode of operation of Port A in PPI 8255?

    <p>Mode 0, mode 1, or mode 2 of input-output mode</p> Signup and view all the answers

    In which mode does the PPI 8255 work if the MSB of the control word (D7) is 0?

    <p>Bit set reset (BSR) mode</p> Signup and view all the answers

    Which pin is used as the Reset input in PPI 8255?

    <p>RESET</p> Signup and view all the answers

    What is the function of the A1 and A0 pins in PPI 8255?

    <p>Address input</p> Signup and view all the answers

    Which mode of operation does PPI 8255 work in if the MSB of the control word (D7) is 1?

    <p>Input-Output mode</p> Signup and view all the answers

    Which statement best describes the Handshake I/O mode of PPI 8255?

    <p>Port A or Port B can work as simple input port or simple output port, and port C bits are used for handshake signals before actual data transmission.</p> Signup and view all the answers

    What is the main advantage of the PPI 8255 in terms of versatility?

    <p>It operates in a variety of modes, making it a versatile component in many different systems.</p> Signup and view all the answers

    What is a disadvantage of the PPI 8255 in terms of functionality?

    <p>It is not capable of high-speed data transfer.</p> Signup and view all the answers

    What does the PPI 8255 lack compared to newer I/O interface components?

    <p>High-speed data transfer capability</p> Signup and view all the answers

    What makes the PPI 8255 an affordable option for many applications?

    <p>Its relatively low-cost</p> Signup and view all the answers

    What type of signals are represented by physical variables and change smoothly over time?

    <p>Analog signals</p> Signup and view all the answers

    Which devices commonly generate analog signals corresponding to the intensity of light in a scene?

    <p>CCD and CMOS image sensors</p> Signup and view all the answers

    What type of signals can only take a finite set of values?

    <p>Digital signals</p> Signup and view all the answers

    Which type of sensors commonly measure temperature and produce an analog voltage proportional to the measured temperature?

    <p>Thermocouples and resistance temperature detectors (RTDs)</p> Signup and view all the answers

    What is the main advantage of digital signals over analog signals?

    <p>They are less susceptible to noise and signal degradation</p> Signup and view all the answers

    What is the role of DACs in embedded systems?

    <p>Converting digital signals into analog signals for actuators and analog instruments</p> Signup and view all the answers

    What is the function of ADCs in the context of analog and digital signals?

    <p>Sampling the input signal at a specified rate and quantizing the sample value into a finite set of discrete values</p> Signup and view all the answers

    In what way do digital signals contribute to efficiency in processing?

    <p>They can be processed and manipulated more efficiently using digital logic circuits</p> Signup and view all the answers

    What characterizes embedded systems in smart homes?

    <p>They generate and process both analog and digital signals to control lighting, heating, and security systems</p> Signup and view all the answers

    What makes digital signals more resilient compared to analog signals?

    <p>Their discrete nature makes them less susceptible to noise, crosstalk, and signal degradation</p> Signup and view all the answers

    Study Notes

    PPI 8255

    • PPI 8255 is a Programmable Peripheral Interface (PPI) device.
    • It consists of three 8-bit bidirectional I/O ports: Port A, Port B, and Port C.

    Port C

    • Port C is used for control and status operations.

    Control Groups

    • PPI 8255 has two control groups.

    Port Selection

    • The value of the control word (D7-D0) is used to select different ports in different modes as input-output functions or BSR (Bit Set Reset) in PPI 8255.

    Mode of Operation

    • Port A operates in I/O mode or BSR mode.
    • If the MSB of the control word (D7) is 0, PPI 8255 works in I/O mode.
    • If the MSB of the control word (D7) is 1, PPI 8255 works in BSR mode.

    Reset Input

    • The Reset input is connected to pin 36 (Reset).

    Address Lines

    • A1 and A0 pins are used as address lines to select different modes.

    Handshake I/O Mode

    • In Handshake I/O mode, PPI 8255 can perform input/output operations with a handshake protocol.

    Advantages and Disadvantages

    • The main advantage of PPI 8255 is its versatility.
    • A disadvantage of PPI 8255 is its limited functionality.
    • PPI 8255 lacks the capabilities of newer I/O interface components.

    Cost Effectiveness

    • PPI 8255 is an affordable option for many applications due to its low cost.

    Signal Types

    • Analog signals are represented by physical variables and change smoothly over time.
    • Analog signals are commonly generated by devices such as light sensors, which measure the intensity of light in a scene.
    • Digital signals can only take a finite set of values.

    Analog and Digital Signals

    • Analog signals are converted to digital signals using Analog-to-Digital Converters (ADCs).
    • Digital signals are converted to analog signals using Digital-to-Analog Converters (DACs).
    • The main advantage of digital signals over analog signals is their resistance to noise and interference.
    • Digital signals contribute to efficiency in processing by allowing for fast and accurate processing.

    Embedded Systems

    • Embedded systems in smart homes are characterized by the use of digital signals.
    • Digital signals are more resilient compared to analog signals due to their ability to withstand noise and interference.

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    Description

    Test your knowledge about the PPI 8255, a versatile programmable I/O device used to interface microprocessors with external components such as ADC, DAC, and keyboards. This quiz covers its features, programming, and applications.

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