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Andy Neil
10/01/03 02:45
Read: 3291 times
Basingstoke
Uk


 
#55866 - RE: How to use 7-segments.
Responding to: ???'s previous message
You could use an external decoder/driver chip to do it all for you.

In software, a Lookup Table is the obvious answer.

First, you need to determine the bit patterns necessary to light the individual segments; eg,
// The seven individual segments are identified as "A" to "G";
// The bit values of the segments are illustrated below:
//
//            A:
//           0x01
//          ------
//         |      |
//  F: 0x20|      | B: 0x02
//         |  G:  |
//          ------
//         | 0x40 |
//  E: 0x10|      | C: 0x04
//         |      |
//          ------
//            D:        DP (Decimal Point): 0x80
//           0x08
//
// A '1' in a pattern turns the segment 'ON'
I then define symbolic constants for each segment:
#define SEG_A  0x01
#define SEG_B  0x02
#define SEG_C  0x04
etc, ...
You then have to draw out how you want each value to display, and construct your table accordingly; eg,
    // Lookup table for hex nibble values
    code unsigned char segments[] =
    {
        /* 0 */ SEG_A | SEG_B | SEG_C | SEG_D | SEG_E | SEG_F        , // 0
        /* 1 */         SEG_B | SEG_C                                , // 1
        /* 2 */ SEG_A | SEG_B |         SEG_D | SEG_E |         SEG_G, // 2
        /* 3 */ SEG_A | SEG_B | SEG_C | SEG_D |                 SEG_G, // 3
        /* 4 */         SEG_B | SEG_C |                 SEG_F | SEG_G, // 4
etc,...

Simple, eh?

You will probably also want to use the 'Search' facility on this forum to search for "multiplexing"

(of course, on a Triscend E5, I'd do the whole lot - multiplexing and all - in the configurable logic!)

List of 5 messages in thread
TopicAuthorDate
How to use 7-segments.      Jose Luis      10/01/03 02:13      
   RE: How to use 7-segments.      Andy Neil      10/01/03 02:45      
   RE: How to use 7-segments.      Félix Díaz      10/01/03 12:51      
   RE: How to use 7-segments.      Seema Oshi      10/02/03 03:23      
      RE: How to use 7-segments.      Andy Neil      10/02/03 05:43      

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