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Bar graph

chandu sri

Hi

In my project iam measuring the leak rate.

The range of leak rate is 1.0E-11 to 1.0E-02.Up now I measured leak rate and displayed
On the 7 segment display with 0.1 resolution. Here I used look up table method I taken hole Range values In the table and iam displaying the value for corresponding voltage .
I stored values in the farm Of (1011 =1.0E-11) here "." ,"E","-" are constants.

Now I want display the leak rate on BAR graph display.
For 20 digits I have to take one led.

The fallowing values I have to show on bar graph
1E-11, 3E-11, 5E-11, 7E-11, 9E-11, 1E-10,
3E-10, 5E-10…………………………………………2E-02

ex:
1E-11 = one led should glow
3E-11 = 2 leds should glow
5E-11 = 3 leds should glow
:
:
:


How to convert table values in to bar graph display.

Thanks

Regards

Parents
  • 0 in reply to erik malund 

    #define NumLeds 12
Value Threshold[NumLeds] =
    {
    // for each LED, list the value at which
    // the LED should turn on
    };


currentValue = GetCurrentValue();

// go through all LEDs, lowest to highest,
// and turn on all those LEDs for which the
// current value is greater than its threshold
for (led = 0; led < NumLeds; ++led)
   {
   if (currentValue >= Threshold[led])
       {
       // current value is at least high enough
       // to activate this LED
       SetLed (led, LedOn);
       }
   else
       { // turn off LEDs
       // current value no longer high enough
       // to activate this LED
       SetLed (led, LedOff)
       }
   }


    If you just want one segment of the bar to turn on, at the current level, then instead of turning on LEDs all the way up, you could just remember the index of the highest value matched, and then turn the corresponding LED on. (You'll also have to remember the last LED activated so you can turn it off.)

Reply
  • 0 in reply to erik malund 

    #define NumLeds 12
Value Threshold[NumLeds] =
    {
    // for each LED, list the value at which
    // the LED should turn on
    };


currentValue = GetCurrentValue();

// go through all LEDs, lowest to highest,
// and turn on all those LEDs for which the
// current value is greater than its threshold
for (led = 0; led < NumLeds; ++led)
   {
   if (currentValue >= Threshold[led])
       {
       // current value is at least high enough
       // to activate this LED
       SetLed (led, LedOn);
       }
   else
       { // turn off LEDs
       // current value no longer high enough
       // to activate this LED
       SetLed (led, LedOff)
       }
   }


    If you just want one segment of the bar to turn on, at the current level, then instead of turning on LEDs all the way up, you could just remember the index of the highest value matched, and then turn the corresponding LED on. (You'll also have to remember the last LED activated so you can turn it off.)

Children
  • 0 in reply to Drew Davis

    Thanks for reply

    Here I wane glow 50 leds means I have to send 50 ones on to the port.

    My doubt is how to store the 50 ones in the array?

    Here I well use 7 latches (8 bit data * 7 latches =48 bits).

    So I well send only 8 bits on to the port. For 48 bits I want send 7 times on to the PORT.

    Ex:


    /* First 8 bits */

    C1=0;/* latch disable*/
    P1=8 bit data;
    C1=1;/* latch enable*/


    /*Second 8 bits */

    C1=0;/* latch disable*/
    P1=8 bit data;
    C1=1;/* latch enable*/


    /* Third 8 bits */

    C1=0;/* latch disable*/
    P1=8 bit data;
    C1=1;/* latch enable*/

    :
    :


    /* Seven 8 bits */

    C1=0;/* latch disable*/
    P1=8 bit data;
    C1=1;/* latch enable*/


    How to divide the 48-bit number in to seven 8-bit numbers?

    Regards
    Sri

  • 0 in reply to chandu sri

    "How to divide the 48-bit number in to seven 8-bit numbers?"

    Why 48 bits?
    If you have 50 LEDs, you need 50 bits!

    Keil C51 doesn't have any data type larger than 32 bits anyhow, so you can't do it directly.

    Easiest way is probably to have a 7-byte array:

    array[0] holds bits 0-7;
    array[1] holds bits 8-15;
    :
    :
    array[6] holds bits 48-55 (note you have some spare bits here).

    Hint: Look up the Modulus operator, '%' (percentage sign), in your 'C' textbook - it will come in useful in deciding which bit to set in which byte of the array...