Difference between revisions of "Interfacing Seven Segment with 8051"

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[[Category:8051 tutorials]]
 
[[Category:8051 tutorials]]
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=Schematic=
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In the earlier tutorials, we saw how to interface the LEDs to PIC microcontroller and wrote the code to blink them. However, the LEDs cannot be used to display any user information like numbers, chars etc. To display numeric values we can use seven segment displays.<br>
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[[File:Schematic 8051 Interfacing DC_Motor.JPG|680px]]
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In this tutorial, we will interface a seven segment to PIC16f877a and display a single digit decimal counter(0-9).
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=Code=
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Later same will be extended to multiplex 4 seven segment displays to generate a 4-digit counter.
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<syntaxhighlight>
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<br><br><br>
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/* This program demonstrates, control of 2 DC Motors using L293D Driver.
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Four switches connected to P1 Drive 2 motors connected to P2.
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For more details visit the tutorial Page:http://exploreembedded.com/wiki/*/
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#include<reg51.h>
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#define Motors P2
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#define Switches P1
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#define Forward 0x05
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#define Backward 0x0a
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#define Left 0x06
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#define Right 0x09
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#define stop 0x00
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=Seven Segment Display=
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void main()
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[[File:BasicSevenSegmentDisplay.png|thumbnail|Basic 7 segment Display]]
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{ 
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Well, the name 7 segments imply there are 7 LED segments arranged as shown in figure 1.
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unsigned char SwitchInput; 
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After LEDs, these are the easiest interfaces to a microcontroller.
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Switches = 0x0f; //Configure Switches  as Input   
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There is also a decimal point or dp. It is used when decimal digits like 5.1 etc are displayed.
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Motors = 0X00; //Configure both Motors as Output.
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==Applications==
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while(1)  
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Seven segments are widely used in applications where digits[0-9] are required to be displayed.Although they also display letters A to F as shown in figure(2) simulation.
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{  
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This is a very simple and convenient way to display numbers in a bright fashion.
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  SwitchInput = (0x0f & Switches);//read switch status and mask lower byte.    
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==Form Factor==
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  switch(SwitchInput)  
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  {  
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*'''Sizes''':They come in various sizes; 0.28”, 0.3”, 0.32”, 0.36”, 0.39”, 0.4”, 0.5”, 0.56”, 0.6”, 0.8”, 1.0”, 1.2”, 1.5”, 1.8”, 2.0”, 2.3”, 3.0”, 4.0”, 5.0”, 7.0”)  
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  case 1: Motors = Forward; break;  
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*'''Colors''': and varied colors too; Red, Green, Yellow, Orange, Blue, and White.
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  case 2: Motors = Backward; break;  
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<br><br>
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  case 4: Motors = Left; break;  
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  case 8: Motors = Right; break;  
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  default: Motors =stop;
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=Working=
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  } 
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Since these are basically LEDs arranged as a group they can either have the anode in common or cathode thus they are named as Common-Anode/Common-Cathode displays.
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}
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[[File:Common Cathode 7Segment.jpeg|thumbnail]]
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}
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[[File:Common Anode 7Segment.jpeg|thumbnail]]
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</syntaxhighlight>
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*<b>Common Cathode</b>: In this type of segments all the cathode terminals are made common and tied to GND. Thus the segments  '''a''' to '''g''' needs a logic High signal(5v) in order to glow. <br><br>
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*<b>Common Anode</b>: In this type of segments all the anodes terminals are made common and tied to VCC(5v). Thus the segments '''a''' to '''g''' needs a logic LOW signal(GND) in order to glow.<br>
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<br><br><br><br>
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[[FILE:0SevenSegment.gif]]
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Below table shows the binary/hex values for displaying the digits on  CommonAnode seven segment display.
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{| class="table table-striped table-hover table-condensed table-bordered"
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|-class="info"
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|Digit || h ||  g ||  f ||  e ||  d ||  c ||  b || a || Hex Value
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|-
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|0 || 1 ||  1  || 0 || 0 || 0 || 0 || 0 || 0 || 0xC0
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|-                                             
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|1 || 1  ||  1  || 1 || 1 || 1 || 0 || 0 || 1 || 0xF9
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|-                                             
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|2 || 1  ||  0  || 1 || 0 || 0 || 1 || 0 || 0 || 0xA4
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|-                                             
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|3 || 1  ||  0  || 1 || 1 || 0 || 0 || 0 || 0 || 0xB0
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|-                                             
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|4 || 1  ||  0  || 0 || 1 || 1 || 0 || 0 || 1 || 0x99
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|-                                             
 +
|5 || 1  ||  0  || 0 || 1 || 0 || 0 || 1 || 0 || 0x92
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|-                                             
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|6 || 1  ||  0  || 0 || 0 || 0 || 0 || 1 || 0 || 0x82
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|-                                             
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|7 || 1  ||  1  || 1 || 1 || 1 || 0 || 0 || 0 || 0xF8
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|-                                             
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|8 || 1  ||  0  || 0 || 0 || 0 || 0 || 0 || 0 || 0x80
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|-                                             
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|9 || 1  ||  0  || 0 || 1 || 0 || 0 || 0 || 0 || 0x90
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|}
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<br><br>
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=Hardware Connection=
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Below image shows the hardware connection as per the table.<br>
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{| class="table table-striped table-hover table-condensed table-bordered"
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|-class="info"
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!a || b || c || d || e || f || g || h || COM
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|-
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|PD0  || PD1  || PD2  || PD3 || PD4 || PD5 || PD6 || PD7 || VCC
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|}
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<br><br>
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[[File:7SegmentSignleDigit bb.png|none]]
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=Code: Single Segment=
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Below is the sample code to display single digit up counter.
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<html>
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<script src="https://gist.github.com/SaheblalBagwan/436101343ba0a1a0e8eb6f6c9140e538.js"></script>
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</html>
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<br><br>
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=Hardware Connections=
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[[File:7Segment4Digit bb.png|none]]
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=Code: Four Segments=
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Below is the sample code for multiplexing four segments to display 4-digit up counter.
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<html>
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<script src="https://gist.github.com/SaheblalBagwan/d6952b2b0efa63becd32ea71eb06acd3.js"></script>
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</html>
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=Downloads=
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Download the complete project folder from the below link:<br>
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[https://github.com/ExploreEmbedded/8051_DevelopmentBoard Hardware design Files and Code Library]
 +
 
 +
 
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Have an opinion, suggestion , question or feedback about the article let it out here!
 +
{{DISQUS}}

Revision as of 13:21, 27 August 2016

In the earlier tutorials, we saw how to interface the LEDs to PIC microcontroller and wrote the code to blink them. However, the LEDs cannot be used to display any user information like numbers, chars etc. To display numeric values we can use seven segment displays.
In this tutorial, we will interface a seven segment to PIC16f877a and display a single digit decimal counter(0-9). Later same will be extended to multiplex 4 seven segment displays to generate a 4-digit counter.


Seven Segment Display

Basic 7 segment Display

Well, the name 7 segments imply there are 7 LED segments arranged as shown in figure 1. After LEDs, these are the easiest interfaces to a microcontroller. There is also a decimal point or dp. It is used when decimal digits like 5.1 etc are displayed.

Applications

Seven segments are widely used in applications where digits[0-9] are required to be displayed.Although they also display letters A to F as shown in figure(2) simulation. This is a very simple and convenient way to display numbers in a bright fashion.

Form Factor

  • Sizes:They come in various sizes; 0.28”, 0.3”, 0.32”, 0.36”, 0.39”, 0.4”, 0.5”, 0.56”, 0.6”, 0.8”, 1.0”, 1.2”, 1.5”, 1.8”, 2.0”, 2.3”, 3.0”, 4.0”, 5.0”, 7.0”)
  • Colors: and varied colors too; Red, Green, Yellow, Orange, Blue, and White.




Working

Since these are basically LEDs arranged as a group they can either have the anode in common or cathode thus they are named as Common-Anode/Common-Cathode displays.

Common Cathode 7Segment.jpeg
Common Anode 7Segment.jpeg
  • Common Cathode: In this type of segments all the cathode terminals are made common and tied to GND. Thus the segments a to g needs a logic High signal(5v) in order to glow.

  • Common Anode: In this type of segments all the anodes terminals are made common and tied to VCC(5v). Thus the segments a to g needs a logic LOW signal(GND) in order to glow.





0SevenSegment.gif

Below table shows the binary/hex values for displaying the digits on CommonAnode seven segment display.

Digit h g f e d c b a Hex Value
0 1 1 0 0 0 0 0 0 0xC0
1 1 1 1 1 1 0 0 1 0xF9
2 1 0 1 0 0 1 0 0 0xA4
3 1 0 1 1 0 0 0 0 0xB0
4 1 0 0 1 1 0 0 1 0x99
5 1 0 0 1 0 0 1 0 0x92
6 1 0 0 0 0 0 1 0 0x82
7 1 1 1 1 1 0 0 0 0xF8
8 1 0 0 0 0 0 0 0 0x80
9 1 0 0 1 0 0 0 0 0x90



Hardware Connection

Below image shows the hardware connection as per the table.

a b c d e f g h COM
PD0 PD1 PD2 PD3 PD4 PD5 PD6 PD7 VCC



7SegmentSignleDigit bb.png

Code: Single Segment

Below is the sample code to display single digit up counter.



Hardware Connections

7Segment4Digit bb.png

Code: Four Segments

Below is the sample code for multiplexing four segments to display 4-digit up counter.

Downloads

Download the complete project folder from the below link:
Hardware design Files and Code Library


Have an opinion, suggestion , question or feedback about the article let it out here!

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