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Friday, 19 September 2014

Circuit to Control a Cluster of 8 Common Cathode SSD by Arduino Mega (Part 1 of 16)

by realfinetime  |  in Seven Segment Display at  05:13

<<<< Previous : Convert Segments of a cluster of 8 Seven Segment Displays to 8*8 LED Matrix

          In the past few blogs , we found the circuit for converting the segments of a cluster of eight common cathode seven segment displays to an 8*8 LED matrix. Converting the cluster of common cathode seven segment displays to 8*8 LED matrix will help to reduce the number of control terminals. That is, in normal case, nine control pins (eight anode and one cathode terminal) are needed to control one seven segment display. For eight common cathode seven segment displays, 8*9 control terminals will be needed. But, if a cluster of eight common cathode seven segment displays is arranged in the form of an 8*8 LED matrix, only sixteen control pins is required to control the entire cluster. That is, 72 control pins is reduced to 16 control pins. To control these 16 pins, an arduino mega and two 74595 shift register ICs are used. Circuit is given below. If the circuit is not clear, download it to your computer (Right click on the circuit => Save image as) and open in a suitable image viewer.
See Larger Image in Pinterest

Pin out diagram of common cathode seven segment display is given below.
Pin out diagram of 74595 shift register IC is given below.

          In the circuit, two 74595 ICs are connected to arduino mega. ST_CP (Pin 12), SH_CP (pin 11) and DS (pin 14) pins of both 74595s are connected to seperate digital pins of arduino mega. MR pin (pin 10) of both 74595s are connected to the VCC pin (pin 16) of 74595s. Similarly, OE pin (pin 13) of both seven segment displays are connected to the Gnd pin (pin 8) of 74595s. Gnd pin of arduino mega should be connected to the Gnd (pin 8) pin of 74595.

Connection between Arduino mega and 74595 ICs can be summarized as :

5th digital pin of arduino mega is connected to the DS pin (pin 14) of 2nd 74595.
6th digital pin of arduino mega is connected to the ST_CP pin (pin 12) of 2nd 74595.
7th digital pin of arduino mega is connected to the SH_CP pin (pin 11) of 2nd 74595.

11th digital pin of arduino mega is connected to the DS pin (pin 14) of 1st 74595.
12th digital pin of arduino mega is connected to the ST_CP pin (pin 12) of 1st 74595.
13th digital pin of arduino mega is connected to the SH_CP pin (pin 11) of 1st 74595.

Continued in Next Page (Part 2) >>>>

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IMPORTANT NOTICE

All the circuits, published in this blog is only after testing and getting proper results in my private lab. When you try these circuits, you should check the supply voltage, polarity of components, presence of childrens nearby and shorts in the circuits. This website will not be responsible for any harm happened to you or your components caused by your carelessness.

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