parameters i am looking for display

Discussion in 'The Projects Forum' started by raksha singh, Feb 15, 2011.

  1. raksha singh

    Thread Starter New Member

    Feb 14, 2011
    9
    0
    parameters i look for display
    hello

    as i am designing a voltmeter in that i have to connect my seven segment display with my controller.for connecting what parameter should i look for .please any one can help me with this so i can make my controller compatible with display,my controller is msp430f2112. ​
     
  2. edgetrigger

    Member

    Dec 19, 2010
    133
    19
    I presume you want to interface a seven segment LED display.



    Parameters required are:

    1. Look for common anode seven segment display as most controllers can easily sink more current than they can source. Common cathode LED display can also be used if the controller can source the current. For your specific controller common anode is more suitable.


    2. As your application is a volt meter you have to decide on the number of digits required which is dependent on the range and resolution of measurement.



    3. The display drive can be either multiplexed one or you can use multiple shift registers in serial configuration(only two wires are required).
    4. Most displays glow bright enough to be seen starting from 0.5ma to 3ma. The current limiting resistor is to be used and resistance is calculated by

    Res = (Vcc-voltage drop of one segment) / segment current
     
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  3. raksha singh

    Thread Starter New Member

    Feb 14, 2011
    9
    0
    hii
    i got so much help from your suggestion .i am new in electronics so i dont have much idea.i have some specified parameters like have to use common cathode display,three and 1/2 digit is required ,and resolution should be 100v.and i have finallised msp4302112series for my controller.so help me with all these specified parameters.how i can make controller compatible with seven segment led display .
     
  4. edgetrigger

    Member

    Dec 19, 2010
    133
    19
    No problem you will master electronics in no time if understand the basics of components. I think you have confusion on range and resolution. 3 and half digit reads upto 1999 it is called half because the first digit can read either 0 or 1. So we have 2000 counts from 0 to 1999 in a 3 and a half digit.


    Some Range and resolution that we can have on a 3.5 digit voltmeter:
    Range
    Resolution
    0 - 1999 volts
    1 Volt
    0 - 199.9 volts
    0.1 volt
    0 – 19.99 Volts
    0.01 v
    0 – 1.999 volts
    0.001
    0 - .1999 volts
    0.0001

    Each segment pin has to be connected to a port pin of your controller through a resistor(use 1k, 1/4w axial throughole resistor). The common anode point needs to be driven through a PNP transistor. I will upload the shcematic tonight, i am using protel software and that does not have a pdf output let me figure out the easiest way to upload schematics.

    What are you studying pregrad or undergrad ?
     
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  5. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    That's why colleges and universities can't keep up with all the EE applicants. That, and the long list of C++ applicants are choking the registrar's office nation wide. Last I heard, it's near crisis proportions. :rolleyes:
     
  6. raksha singh

    Thread Starter New Member

    Feb 14, 2011
    9
    0
    hello sir
    thank you sir for your reply .your information is quite fruitfull for me,but related with this i have so many doubts.can you please suggest me any thing throgh that i can clear all my doubts and if possible please send me schematic in altium.and if any other source you can suggest me ,that would be great for me.

    i have just completed my b.e(EC).
     
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