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pressure

chandu sri

hi sir

i need one help

now iam doing project on 89c51 using C51 Evaluation Software

i converted 0-5 analog volatge to 0-5 digital voltage .

now i want convert digital data to pressure

my output should be like this

0v 1.1E-1 3v 4.1E-4
0.1 1.2E-1 4v 5.1E-5
1v 2.1E-2 5v 6.1E-6
2v 3.1E-3

i want 500 values in between 0 to 5 volts
how to calibrate the voltage interms of preesure
what logic i want use to convert Voltage to pressure
my C51 not taking floting oparations

please help

regards
chandra sri

Parents
  • 0 in reply to Andy Neil

    thank you sir

    thank you for your valueble answers

    Hear in my project iam using 4 seven segment display for to display the pressure.

    up to now iam displaying the pressure on the serial window.

    pleace tell how to display the data on 7 segment display with out using printf statement.

    Because printf is taking lot of memory .

    regards

    chandu

Reply
  • 0 in reply to Andy Neil

    thank you sir

    thank you for your valueble answers

    Hear in my project iam using 4 seven segment display for to display the pressure.

    up to now iam displaying the pressure on the serial window.

    pleace tell how to display the data on 7 segment display with out using printf statement.

    Because printf is taking lot of memory .

    regards

    chandu

Children
  • 0 in reply to chandu chi

    "in my project iam using 4 seven segment display for to display the pressure."

    Do you mean a four-digit 7-segment display?

    If so, how do you plan to display, for example, "4.1E-4" on four 7-segment digits:

    4. = 1st digit
1  = 2nd digit
E  = 3rd digit
-  = 4th digit
4  = Oops! no more digits!!
    Or, as all the values contain the 'E' and '-', will they just be permanently marked on the panel?
    In which case, you only need 3 digits - not 4!

    "please tell how to..."

    No - you need to learn how to think these things out for yourself!

    The Lookup-Table technique can still be used; you could even still make it a table of strings.
    Instead of using printf, you just write the 1st character of the string to the left-most 7-segment digit, and so on...

    Using a table of strings for this is probably quite inefficient, because:
    1. each string has a null-terminator added, which you don't need;
    2. the actual table contains pointers to the strings (textbook basics) - so these pointers have to be stored in addition to the actual strings, With such small strings, this is a significant overhead!

    A more compact way would be to use a two-dimensional array...

    Textbook time, again!

    "Because printf is taking lot of memory"

    Yes, printf does take quite a lot of memory.
    But, in this case are you sure that it's printf that's the real problem - or is it just the size of the table?

  • 0 in reply to chandu chi

    "in my project iam using 4 seven segment display for to display the pressure."

    Do you mean a four-digit 7-segment display?

    If so, how do you plan to display, for example, "4.1E-4" on four 7-segment digits:

    4. = 1st digit
1  = 2nd digit
E  = 3rd digit
-  = 4th digit
4  = Oops! no more digits!!
    Or, as all the values contain the 'E' and '-', will they just be permanently marked on the panel?
    In which case, you only need 3 digits - not 4!

    "please tell how to..."

    No - you need to learn how to think these things out for yourself!

    The Lookup-Table technique can still be used; you could even still make it a table of strings.
    Instead of using printf, you just write the 1st character of the string to the left-most 7-segment digit, and so on...

    Using a table of strings for this is probably quite inefficient, because:
    1. each string has a null-terminator added, which you don't need;
    2. the actual table contains pointers to the strings (textbook basics) - so these pointers have to be stored in addition to the actual strings, With such small strings, this is a significant overhead!

    A more compact way would be to use a two-dimensional array...

    Textbook time, again!

    "Because printf is taking lot of memory"

    Yes, printf does take quite a lot of memory.
    But, in this case are you sure that it's printf that's the real problem - or is it just the size of the table?

  • 0 in reply to Andy Neil

    Textbook time, again!

    Andy, do not come to the US, we have laws against cruel and unusual punishment :)

    Erik

  • 0 in reply to erik malund

    we have laws against cruel and unusual punishment

    Textbook time may be cruel, but it is certainly not unusual, and therefore perfectly fine. :)

  • 0 in reply to Christoph Franck

    "Textbook time ... is certainly not unusual"

    It seems to be becoming increasingly unusual amongst today's students... :-(

  • 0 in reply to Andy Neil

    hi sir

    this is my code

    {
    unsigned int voltage;
    unsigned char *pressure_string[] ={"3.07E-12","1.22E-10","6.56E-10");
    v=0x02;
    voltage=voltage*50;
    P1=string[voltage];
    }


    For voltage=0x02 carresponding pressure is

    6.56E-10 from table.

    that is P1=6.56E-10;

    sir my doubt is PORT 1 well takes only 1 byte

    (8bits) then how it takes 6.56E-10;

    and how to devide the pressure 6.56E-10

    into "6",".=constant","5","6","E=constant",

    "-=constant","1","0" .

    sir here iam using seven numbers 7segment

    Led display for displaying the pressure.

    thank you sir

    Regards

    chandu

  • 0 in reply to Andy Neil

    Hi sir

    how to divide the "string" into singal elements

    example:

    string={"3.56E-12") in to "3", "." ,"5","6","E","-","1","2".

    Thank you

    Regards

    chandu

  • 0 in reply to chandu chi

    Stop! Now!!

    You are struggling with absolutely basic concepts of both 'C' programming and, apparently, the hardware itself.

    You seriously need to set this project aside, go back to basics, and get a proper understanding in the 'C' Language

    Get yourself a good book, and study it:
    http://www.keil.com/books/8051books.asp
    http://www.8052.com/books.phtml


    "my doubt is PORT 1 well takes only 1 byte (8bits) ... i am using seven numbers 7segment LED display"

    Sure, all the 8051's ports are 8 bits (1 byte) wide.
    So how have you connected seven 7-Segment digits to your 8051?

    Obviously, the way you write stuff to the display will depend entirely on how it is connected to the 8051!!