A digital system like a computer can understand and easily read a large number in binary format. However, a human cannot read large binary numbers.
To solve this problem we need to display it as a decimal digit using 7-segment display. It is a digital device that can be used for displaying decimal number, alphabets, and characters. Generally, there are 8 input pins in a 7-Segment display. There are two types of 7-Segment displays. In such type of 7-segment display, all the cathodes of the 7 LEDs are connected together to form a common terminal.
The type of 7-Segment display in which all the anode terminals of 7 LEDs are connected together to form common anode terminal. Each of the pins will illuminate the specific segment only. We assume common cathode LED segment as our example.
Display combination of decimal numbers is given below. Digit 1 : to display the digit 1 we need to turn on the segments b, c. This configuration will result in the display as shown in the figure below. Digit 2 : to display the digit 2 we need to turn on the segments a, b, d, e, g.
Digit 3 : to display the digit 3 we need to turn on the segments a, b, c, d, g. Digit 4 : to display the digit 4 we need to turn on the segments b, c, f, g.
Digit 5 : to display the digit 5 we need to turn on the segments a, c, d, f, g. Digit 6 : to display the digit 6 we need to turn on the segments a, c, d, e, f, g. Digit 7 : to display the digit 7 we need to turn on the segments a, b, c. I did for b but I keep having issues with a Reply.
Boolean expression is the result of K MAP simplification. Leave a Reply Cancel reply. Support Invent Logics. Loading Comments Email Required Name Required Website. Sorry, your blog cannot share posts by email. We use cookies to ensure that we give you the best experience on our website. By using our site you agree to our use of cookies. Here we design a simple display decoder circuit using logic gates. Even though commercial BCD to 7 segment decoders are available, designing a display decoder using logic gates may prove to be beneficial from economical as well as knowledge point of view.
Back to top. The basic idea involves driving a common cathode 7-segment LED display using combinational logic circuit. The logic circuit is designed with 4 inputs and 7 outputs, each representing an input to the display IC.
The first and foremost aspect of this circuit is decoder. A decoder is a combinational circuit which is used to convert a binary or BCD Binary Coded Decimal number to the corresponding decimal number. It can be a simple binary to decimal decoder or a BCD to 7 segment decoder.
Another relevant section is the combinational logic circuitry. A combinational logic circuit is a system of logic gates consisting of only outputs and inputs. The output of a combinational logic circuit depends only on the present state of the inputs and nothing else. To understand the design and operation of these logic circuits, one needs to have a good knowledge about Boolean algebra and logic gates.
A 7 segment LED display consists of an arrangement of 8 LEDs such that either all the anodes are common or cathodes are common. Step 1: The first step of the design involves analysis of the common cathode 7-segment display. A truth table is constructed with the combination of inputs for each decimal number.
For example, decimal number 1 would command a combination of b and c refer the diagram given below. Step 2: The second step involves constructing the truth table listing the 7 display input signals, decimal number and corresponding 4 digit binary numbers. The truth table for the decoder design depends on the type of 7-segment display. As we mentioned above that for a common cathode seven-segment display, the output of decoder or segment driver must be active high in order to glow the segment.
The figure below shows the truth table of a BCD to seven-segment decoder with common cathode display.
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