1. 7 SEGMENT INTERFACE WITH AVR MICROCONTROLLER A. D. Patel Institute Of Technology EC :- Sem VPresent By :- Pratik Makadia (130010111017) 23 June 2016 1

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. 23 June 2016 2

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. 23 June 2016 3

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. 23 June 2016 4

5. 1)Common anode 23 June 2016 5 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. 23 June 2016 6

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. 23 June 2016 7

8. Block Diagram Of Interfacing 23 June 2016 8

9. Table for all 16 hexadecimal digits and values for all segment to need turn on the proper segment. DigitHex Value g f e d c b a 00x3F 0 1 1 1 1 1 1 10x06 0 0 0 0 1 1 0 20x5B 1 0 1 1 0 1 1 30x4F 1 0 0 1 1 1 1 40x66 1 1 0 0 1 1 0 50x6D 1 1 0 1 1 0 1 60x7D 1 1 1 1 1 0 1 70x07 0 0 0 0 1 1 1 23 June 2016 9 DigitHex Value g f e d c b a 80x7F 1 1 1 1 1 1 1 90x6F 1 1 0 1 1 1 1 A0x77 1 1 1 0 1 1 1 B0x7C 1 1 1 1 1 0 0 C0x39 0 1 1 1 0 0 1 D0x5E 1 0 1 1 1 1 0 E0x79 1 1 1 1 0 0 1 F0x71 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). 23 June 2016 10

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