7 segment interface with avr microcontroller

1. 7 SEGMENT INTERFACE WITH
AVR MICROCONTROLLER
A. D. Patel Institute Of Technology
EC :- Sem V Present By :- Pratik Makadia
(130010111017)
19 October 2015
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2. Introduction
 Seven segment displays are very common for electronic product to
display numerical output.
 Many common devices like calculators, watches, electronic
weighing scales, ovens etc use them.
 You must have also seen in our ADIT lifts display the current floor
numbers in seven segment displays.
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3. Fundamentals
 A seven-segment display is so named because it is divided into
seven different segments that can be switched on or off.
 The different combination of these segments switched on produces
different English numbers.
 The display also has a decimal point.
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4.  The figure shows a seven segment display
and the names of the various segments.
 For example if you want to display
number 4 then segments that will be ‘on’
are {f, g, b, c} while rest are ‘off’. Basically
the seven segments are just LEDs.
 The one common end of all the leds are
connected while the rest are available.
 Depending on whether anode or
cathode of all the leds are common they
are of two types.
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5. 1) Common anode
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2) Common cathode

6. PIN Configuration
 these displays should have
nine pin( one for each
segment + decimal point
+common).
 but the available modules
have two pins for common.
 They are internally
connected. So they have
total of 10 PINs.
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7. Interfacing with MCU
 Interfacing these displays are
same as interfacing LEDs with
MCU.
 I have interfaced a common
anode(+) 7 segment display
with PORTD of AVR using 8-PIN
connectors.
 The segments will be "on"
when levels on the PORT is low,
that is 0.
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8. Block Diagram Of Interfacing
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9. Table for all 16 hexadecimal digits and values for all segment to
need turn on the proper segment.
Digit Hex
Value
g f e d c b a
0 0x3F 0 1 1 1 1 1 1
1 0x06 0 0 0 0 1 1 0
2 0x5B 1 0 1 1 0 1 1
3 0x4F 1 0 0 1 1 1 1
4 0x66 1 1 0 0 1 1 0
5 0x6D 1 1 0 1 1 0 1
6 0x7D 1 1 1 1 1 0 1
7 0x07 0 0 0 0 1 1 1
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Digit Hex
Value
g f e d c b a
8 0x7F 1 1 1 1 1 1 1
9 0x6F 1 1 0 1 1 1 1
A 0x77 1 1 1 0 1 1 1
B 0x7C 1 1 1 1 1 0 0
C 0x39 0 1 1 1 0 0 1
D 0x5E 1 0 1 1 1 1 0
E 0x79 1 1 1 1 0 0 1
F 0x71 1 1 1 0 0 0 1

10. Programming
 These displays are very easy to program in C.
 The controller is initialized by sending three commands:
1) Turning on its internal oscillator
2) Enabling display output
3) Setting the brightness level
 Brightness is adjusted from 0 (dimmest) to 15 (brightest).
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