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0000 to 9999 Display in Quad 7-Segment Display with ATmega16

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Things gets a little bit more complicated when we want to have more than one 7-segment display and each one will show a different number. Normally, we would need 8 pins for each one (7 for seven segments and one for DP), so a total of 32 pins are required for four 7-segment display, right? No, because in that way, if we wanted to have 6 digits (for a frequency meter for example) we would need 48 pins! Instead, we will make a trick, a trick with the eye. The catch is that the human eye does not operate non-stop all the time. Instead, it takes 10 ‘photos’ each second. Between those photos, the brain will keep the last photo taken active, something like a ‘latch’. We will take advantage of this characteristic of human eye in this project. This trick or technology is called time sharing. Using this technology, we need only 12 pins of microcontroller to display from 0000 to 9999 in three 7-segment display.

In this project, we will learn How to display from 0000 to 9999 in four common anode 7-segment displays with AVR ATmega16 microcontroller. The four 7-segments are connected to the AVR ATmega16 microcontroller using multiplexing technology to save 20 I/O pins of AVR ATmega16 microcontroller. For detail see the circuit diagram. The microcontroller selects one 7-segment at a time to display one digit of the four digit number. But, the speed at which the microcontroller selects the 7-segment to display the digits is very fast. At this speed, the human eye cannot detect that; at any instant of time only one 7-segment is displaying one digit of the number and the other 7-segments are not displaying anything. The microcontroller displays the numbers from 0000 to 9999 in the four 7-segment displays and the microcontroller uses its compare match interrupt of Timer Counter feature to give a time delay between two consecutive numbers (delay functions cannot be used to give time delay between two consecutive numbers).. When the display reaches 9999, it will restart the display from 0000 and the above process continues forever.

Softwares Required

• AVR Studio 4 Software
• WinAVR 2010 Software
• SinaProg Hex Downloader Software
• USBasp Driver

Hardwares Required

Name	Quantity
AVR Trainer Board-100 with ATmega16	1pc
AVR USB Programmer	1pc
12V, 1A DC SMPS Adaptor	1pc
Quad 7-Segment Display Board	1pc
1 to 1 Connector-Female to Female	4pc
10 to 10 FRC Female to Female Connector	2pc

Video

Connection Guide

The step-by-step connection guide for 0000 to 9999 Display in Quad 7-Segment Display with ATmega16 is as follows