In this Arduino tutorial, we will how to multiplexing seven segment display with a 74hc595 shift register. A single digit display shows 0 to 9 decimal number. Ofen we need to display two, three, four or more digit decimal number, but the problem is lack of I/O (input/output) pins in the MCUs. To solve this problem we need to multiplexing. Here we will also use a 74hc595 shift register.
You can watch the following video below:-
Components Required
The following component needed for this tutorial.
- Arduino Uno
- 2 Common anode 7 segment display
- 74hc595 shift register
- 220-ohm resistor
- Breadboard
- Some jumper wire
Pin Configuration
The following figure shows common anode 7 segment display pinout. It has total 10 pins in which pin 3,8 common pin, pin 5 is DP and remaining pins are a,b,c,d,e,f,g.
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| Fig: Common anode 7 segment display pinout |
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Fig: 74hc595 pinout
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Circuit Schematic
The following figure shows the 7 segment display multiplexing with 74hc595 shift register using Arduino.
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| Fig: 7 Segment display multiplexing |
Circuit Description
The shift register has 16 pins in which 7 output pins will connect with 7 segment LEDs pin. The shift register Vcc pin 16 and MR pin 10 will connect to +5V. The ground pin 8 and output enable pin 13 will goes to ground. Next, shift register clock, latch, and data pins are gradually 11,12 and 14 will connect to Arduino digital pin 2, 3 and 4 respectively. Seven segment display common pins will connect to Arduino digital pin 6 and 7 through the 220-ohm series resistor.
7 segment display ----------------- 74hc595 shift register
Pin_7(Seg_a) --------------- Pin_15(Q_A)
Pin_6(Seg_b) --------------- Pin_1(Q_A)
Pin_4(Seg_c) --------------- Pin_2(Q_A)
Pin_2(Seg_d) --------------- Pin_3(Q_A)
Pin_1(Seg_e) --------------- Pin_4(Q_A)
Pin_10(Seg_f) -------------- Pin_5(Q_A)
Pin_9(Seg_g) -------------- Pin_6(Q_A)
Source Code
This is the source code of multiplexing given below:-
Thanks for the project. I got it working with a single two digit LED module instead of the two separate one digit modules. I spotted one error. You specify pins 6 and 7 in the wiring diagram but define pins 5 and 6 in the code. Once I’d corrected the code it all worked perfectly.
ReplyDeletewhy "display1 and 2" meke error
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