Help on choosing the right ICs

Discussion in 'The Projects Forum' started by evios, Nov 9, 2008.

  1. evios

    Thread Starter Member

    Nov 9, 2008
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    Hi for the experts here, I am currently implementing Automatic Meter Reading using wireless Zigbee 802.15.4. I was intended to use a digital electrical meter, which has 7 segment reading indicate the current reading of the meter. Each of the 7 segment will has its pins. To capture the reading, i get the High Low input from these pins. However my problem arise here:

    i. What do i need to do to transform the reading into an IC input?
    ii. Any ICs that can periodically store the latest reading from the meter?

    Hardware: Ember Developement Kit

    Thank you.:)
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You can use a register IC to store the meter reading.
    What exactly you want to do?
    Do you want to transmit the meter reading to another place and view it on a display?
     
  3. evios

    Thread Starter Member

    Nov 9, 2008
    29
    0
    Emm...
    Basically I will need the reading from the digital meter.
    But for the intermediate, i dont have any idea on how to transfer the reading from the meter to IC. As there are 10 pins for 7 segment display, lets say if the meter has 6 digits of the reading, I might have 60 inputs of High and Low. How do I translate the reading to the input of an ICs?
    Thanks for your kind reply.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    282
    You seem to imply that the display is multiplexed. It would be easier to make sense of the actual value to go deeper into the metering IC and get the numbers before they get converted to BCD for driving the display digits.

    What were you planning on installing in the meter to get and transmit the reading?
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    If your IC has 60 inputs, as you calculated you will need, then you can connect the pins of the 7 seg display to the IC pins with some additional resistors if needed. Otherwise, you will need a multiplexer to multiplex the 60 pins to 5. Take care the voltage on the 7 seg display pins is not high for your IC. Are you going to use a microcontroller to control the whole thing?
     
  6. evios

    Thread Starter Member

    Nov 9, 2008
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    Em... thanks. I will go further details on the meter. By the way are you familiar with eectrical digital meter? Thanks
     
  7. evios

    Thread Starter Member

    Nov 9, 2008
    29
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    Well, as for the whole concept is:
    An IC periodically capture the reading from the meter.
    An MCU (from the Zigbee module) will access and get the reading from the ICs.
    I just need to know which ICs has the similar functions as to get the meter reading periodically and translate the reading into a readable form to the MCU.
    Thanks again for your reply.
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    Have you approached the issue of legality here? No utility company I am aware of will allow anyone to open and install equipment in a watthour meter.

    Also. are you aware that many power companies use power line transmission to read the installed meters?
     
  9. evios

    Thread Starter Member

    Nov 9, 2008
    29
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    Yes, i aware of that.
    This is my final year project, so everything goes in small budget.
    The digital power meter i used as I know from my lecturer is a simple one, in digital.
    I am using Zigbee transmission instead of power line.
     
  10. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Well, i dont know any IC part number but you can combine multiplexers with registers and control them with the MCU to obtain and store the results.
    If the 7-seg displays are driven by a driver IC and not directly from a microcontroller then its better to take the input of the 7-seg driver and store it rather taking its output (7-seg display pins) because you will need less pins on your MCU.
     
  11. evios

    Thread Starter Member

    Nov 9, 2008
    29
    0
    Well, thanks. If I faced any difficulties might seek for the forum again.
    Thanks
     
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