16F 7 Segment Display Example

16F 7 Segment Display Example

   7 segment displays are a cheap and effective way to display data. The only real downsides to them are;

• Unable to retain data
• Require many Pins to interface

    The data that they display can be manipulated so that the same 7 data lines can multiplex information onto other displays at the same time. This can be seen in the Multiple 18F section. But for now, and future routines, this diagram illustrates how to connect a 7 segment display to a PIC micro. This may not be the same wiring diagram that other people have used, but in my projects, it will always be the same with the exception of the common cathode pin on the display.

Schematic

 

Note the PIC's power supply/oscillator are not shown

    The box that the 7 segment is in represents the common. There are two types of 7 segment displays, common cathode and common anode. In my projects, I use common cathode displays. i.e.

    As you can see, to control any of the segments, a +ve signal is required, as they all share the same earth. aka common cathode.

The following example shows how to decode a value between 0-9 into 7 segment data and display it.

Device 16F877

Xtal = 4

Dim Number As Byte

Initialization:

ALL_DIGITAL = True
PORTB_PULLUPS = False

TRISB = %00000000 ' Make PORTB all outputs

Main:

Number = 0

Repeat ' Create a loop

GoSub Encode_Segment_Display ' Convert to segment data and display it

DelaymS 500 ' Small delay to slow down counting
Inc Number ' Increment the Number register

Until Number = 10 ' Loop until number = 10, then reset

Goto Main ' Loop forever

Encode_Segment_Display:

SELECT Number
CASE 0 ' Turn Number into segment display data
PORTB = %00111111
CASE 1
PORTB = %00000110
CASE 2
PORTB = %01011011
CASE 3
PORTB = %01001111
CASE 4
PORTB = %01100110
CASE 5
PORTB = %01101101
CASE 6
PORTB = %01111100
CASE 7
PORTB = %00000111
CASE 8
PORTB = %01111111
CASE 9
PORTB = %01100111
ENDSELECT

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