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Difference between revisions of "seven-segment display"

(Created page with "right|250px A '''seven-segment display''' ('''SSD''') is a display device packaged in a single IC chip and composed of a group of seven bar-...")
 
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There are two basic configurations of seven-segment displays: common cathode (CC) and common anode (CA).  
 
There are two basic configurations of seven-segment displays: common cathode (CC) and common anode (CA).  
 
=== Common Anode ===
 
=== Common Anode ===
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A '''common anode seven-segment display''' is one where the anode leads of all the LEDs are tied together. In a CA SSD, power must be supplied to anode that is common to all the segments. Appropriate segments can be lit up by applying ground to them. In this setup a [[pull-down resistor]]
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A '''common anode seven-segment display''' is one where the anode leads of all the LEDs are tied together. In a CA SSD, power must be supplied to anode that is common to all the segments. Appropriate segments can be lit up by applying ground to them.
  
 
=== Common Cathode ===
 
=== Common Cathode ===
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{{clear}}
 
{{clear}}
 
== Basics ==
 
== Basics ==
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[[File:7 segment display labeled.svg|thumb|200px|right|The individual segments of a seven-segment display.]]
 
 
The various numbers (and possibly A-F) can be displayed by simply powering the correct segments by either connecting GND or Vcc.
 
The various numbers (and possibly A-F) can be displayed by simply powering the correct segments by either connecting GND or Vcc.
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 +
{| class="wikitable" style="text-align: center;"
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!rowspan="2" | Digit !! colspan="4" | [[BCD]] !! colspan="7" | 7-Segments !! rowspan="2" | abcdefg !! rowspan="2" | gfedcba !! rowspan="2" | Display !! rowspan="2" | Reference
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|-
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! D !! C !! B !! A !!      a !! b !! c !! d !! e !! f !! g
 +
|-
 +
| 0 || 0 || 0 || 0 || 0 || 1 || 1 || 1 || 1 || 1 || 1 || 0 || 0x7E || 0x3F || [[File:7-segment abcdef.svg|10px]] || rowspan="16" | [[File:7 segment display labeled.svg|200px]]
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|-
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| 1 || 0 || 0 || 0 || 1 || 0 || 1 || 1 || 0 || 0 || 0 || 0 || 0x30 || 0x06 || [[File:7-segment bc.svg|10px]]
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|-
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| 2 || 0 || 0 || 1 || 0 || 1 || 1 || 0 || 1 || 1 || 0 || 1 || 0x6D || 0x5B || [[File:7-segment abdeg.svg|10px]]
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|-
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| 3 || 0 || 0 || 1 || 1 || 1 || 1 || 1 || 1 || 0 || 0 || 1 || 0x79 || 0x4F || [[File:7-segment abcdg.svg|10px]]
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|-
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| 4 || 0 || 1 || 0 || 0 || 0 || 1 || 1 || 0 || 0 || 1 || 1 || 0x33 || 0x66 || [[File:7-segment bcfg.svg|10px]]
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|-
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| 5 || 0 || 1 || 0 || 1 || 1 || 0 || 1 || 1 || 0 || 1 || 1 || 0x5B || 0x6D || [[File:7-segment acdfg.svg|10px]]
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|-
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| 6 || 0 || 1 || 1 || 0 || 1 || 0 || 1 || 1 || 1 || 1 || 1 || 0x5F || 0x7D || [[File:7-segment acdefg.svg|10px]]
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|-
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| 7 || 0 || 1 || 1 || 1 || 1 || 1 || 1 || 0 || 0 || 0 || 0 || 0x70 || 0x07 || [[File:7-segment abc.svg|10px]]
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|-
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| 8 || 1 || 0 || 0 || 0 || 1 || 1 || 1 || 1 || 1 || 1 || 1 || 0x7F || 0x7F || [[File:7-segment abcdefg.svg|10px]]
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|-
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| 9 || 1 || 0 || 0 || 1 || 1 || 1 || 1 || 1 || 0 || 1 || 1 || 0x7B || 0x6F || [[File:7-segment abcdfg.svg|10px]]
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|-
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| A || 1 || 0 || 0 || 1 || 1 || 1 || 1 || 0 || 1 || 1 || 1 || 0x77 || 0x77 || [[File:7-segment abcefg.svg|10px]]
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|-
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| B || 1 || 0 || 0 || 1 || 0 || 0 || 1 || 1 || 1 || 1 || 1 || 0x1F || 0x7C || [[File:7-segment cdefg.svg|10px]]
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|-
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| C || 1 || 0 || 0 || 1 || 1 || 0 || 0 || 1 || 1 || 1 || 0 || 0x4E || 0x39 || [[File:7-segment adef.svg|10px]]
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|-
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| D || 1 || 0 || 0 || 1 || 0 || 1 || 1 || 1 || 1 || 0 || 1 || 0x3D || 0x5E || [[File:7-segment bcdeg.svg|10px]]
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|-
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| E || 1 || 0 || 0 || 1 || 1 || 0 || 0 || 1 || 1 || 1 || 1 || 0x4F || 0x79 || [[File:7-segment adefg.svg|10px]]
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|-
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| F || 1 || 0 || 0 || 1 || 1 || 0 || 0 || 0 || 1 || 1 || 1 || 0x47 || 0x71 || [[File:7-segment aefg.svg|10px]]
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|}
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In-code decoding can be done easily using a simple [[lookup table]] such as the one below:
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<source lang="C">
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const unsigned char seven_seg_digits_decode_abcdefg[16]=
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{
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/*  0    1    2    3    4    5    6    7    */
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    0x7E, 0x30, 0x6D, 0x79, 0x33, 0x5B, 0x5F, 0x70,
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/*  8    9    A    B    C    D    E    F    */
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    0x7F, 0x7B, 0x77, 0x1F, 0x4E, 0x3D, 0x4F, 0x47
 +
};
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const unsigned char seven_seg_digits_decode_gfedcba[16]=
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{
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/*  0    1    2    3    4    5    6    7    */
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    0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07,
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/*  8    9    A    B    C    D    E    F    */
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    0x7F, 0x6F, 0x77, 0x7C, 0x39, 0x5E, 0x79, 0x71
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};
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</source>
  
 
[[Category:display devices]]
 
[[Category:display devices]]

Revision as of 12:13, 10 November 2015

7 Segment LED.jpg

A seven-segment display (SSD) is a display device packaged in a single IC chip and composed of a group of seven bar-shaped LEDs. Some seven-segment displays may come with a decimal point (DP). Different numbers and letters may be formed by powering selected LED elements. SSDs come in various packages and pin arranges.

Dialog-warning-yellow.svg This article may contain examples using specific pins. Your device pinout may differ. Always consult your datasheet.

Configurations

Common Anode SSD
Common cathode SSD

There are two basic configurations of seven-segment displays: common cathode (CC) and common anode (CA).

Common Anode

A common anode seven-segment display is one where the anode leads of all the LEDs are tied together. In a CA SSD, power must be supplied to anode that is common to all the segments. Appropriate segments can be lit up by applying ground to them.

Common Cathode

a Common cathode seven-segment display is one where the cathode leads of all the LEDs are tied together.

Basics

The various numbers (and possibly A-F) can be displayed by simply powering the correct segments by either connecting GND or Vcc.

Digit BCD 7-Segments abcdefg gfedcba Display Reference
D C B A a b c d e f g
0 0 0 0 0 1 1 1 1 1 1 0 0x7E 0x3F 7-segment abcdef.svg 7 segment display labeled.svg
1 0 0 0 1 0 1 1 0 0 0 0 0x30 0x06 7-segment bc.svg
2 0 0 1 0 1 1 0 1 1 0 1 0x6D 0x5B 7-segment abdeg.svg
3 0 0 1 1 1 1 1 1 0 0 1 0x79 0x4F 7-segment abcdg.svg
4 0 1 0 0 0 1 1 0 0 1 1 0x33 0x66 7-segment bcfg.svg
5 0 1 0 1 1 0 1 1 0 1 1 0x5B 0x6D 7-segment acdfg.svg
6 0 1 1 0 1 0 1 1 1 1 1 0x5F 0x7D 7-segment acdefg.svg
7 0 1 1 1 1 1 1 0 0 0 0 0x70 0x07 7-segment abc.svg
8 1 0 0 0 1 1 1 1 1 1 1 0x7F 0x7F 7-segment abcdefg.svg
9 1 0 0 1 1 1 1 1 0 1 1 0x7B 0x6F 7-segment abcdfg.svg
A 1 0 0 1 1 1 1 0 1 1 1 0x77 0x77 7-segment abcefg.svg
B 1 0 0 1 0 0 1 1 1 1 1 0x1F 0x7C 7-segment cdefg.svg
C 1 0 0 1 1 0 0 1 1 1 0 0x4E 0x39 7-segment adef.svg
D 1 0 0 1 0 1 1 1 1 0 1 0x3D 0x5E 7-segment bcdeg.svg
E 1 0 0 1 1 0 0 1 1 1 1 0x4F 0x79 7-segment adefg.svg
F 1 0 0 1 1 0 0 0 1 1 1 0x47 0x71 7-segment aefg.svg

In-code decoding can be done easily using a simple lookup table such as the one below: 

const unsigned char seven_seg_digits_decode_abcdefg[16]=
{
/*  0     1     2     3     4     5     6     7    */
    0x7E, 0x30, 0x6D, 0x79, 0x33, 0x5B, 0x5F, 0x70,
/*  8     9     A     B     C     D     E     F    */
    0x7F, 0x7B, 0x77, 0x1F, 0x4E, 0x3D, 0x4F, 0x47
};
const unsigned char seven_seg_digits_decode_gfedcba[16]=
{
/*  0     1     2     3     4     5     6     7    */
    0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07,
/*  8     9     A     B     C     D     E     F    */
    0x7F, 0x6F, 0x77, 0x7C, 0x39, 0x5E, 0x79, 0x71
};
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