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Microcontroller block diagram

Discussion in 'Electronics Homework Help' started by Baxter Burgundy, Apr 28, 2016.

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  1. Baxter Burgundy

    Baxter Burgundy

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    Nov 18, 2014
    Not homework as such, just exam preparation.

    I have a practice question asking for a block diagram of an embedded microprocessor system which is used to monitor and control the safety of a plant. The plant setup is composed of various sensors monitoring pressure, temperature and level, and has various actuators for starting pumps, opening and closing valves.

    I expect what they are looking for is a modified version of the harvard architecture of a PIC. I would probably have it interrupt driven with a hierarchy of the primary sensors. Any thoughts?
     

    Attached Files:

  2. dorke

    dorke

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    Jun 20, 2015
    The inner architecture of the μP isn't at all important.
    A sensor polling scheme is well tailored for this application.
    You should have outputs to all control points.
    Take into account that the sensors are basically analog.
    and that a poling scheme may use a pol-timer.
    Hope you can complete from this point?
     
    Baxter Burgundy likes this.
  3. Baxter Burgundy

    Baxter Burgundy

    38
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    Nov 18, 2014
    So something like the picture I've just attached? And to say that a polling system will be used ranking the sensors in order of CT, PCP, PCT, SCP, SCT, RM, Level, and the use a of PIC 16F877 that has 366 bytes of RAM to store the latest reading from the sensors and results of comparisons, 8K of EEPROM to store critical conditions and a Flash for the code?
     

    Attached Files:

  4. dorke

    dorke

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    Jun 20, 2015
    Something like that.
    Notes:
    1. Each "sensor input " may have it's own resolution (translated to number of bits) and speed of change.
    2. The output of a ADC may be parallel or serial.
    3. It may be possible to use just a single ADC and multiplex the sensor inputs to it
    4. Input from the sensors may need to be condition/amplified etc.
    5. Not every actuator need an output DAC some most probably need to be just on-off.
    6. Most actuator will require drivers,the DAC or output of the μP will not be able to drive them directly.
    7. You probably need to show just the CPU itself in a block and the memory types,timers,etc. in separate blocks
     
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  5. Baxter Burgundy

    Baxter Burgundy

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    Nov 18, 2014
    So more like this?
     

    Attached Files:

  6. dorke

    dorke

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    Jun 20, 2015
    Yes, and show the input mux select bits and output drivers connected to the i/o block.
    Add a timer/counter .
    Omit the the pic number-it is a general solution not tight to a specific one μC/μP
     
    Baxter Burgundy likes this.
  7. Baxter Burgundy

    Baxter Burgundy

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    Nov 18, 2014
    Thank you very much
     
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