Show 5 letters on 5 Common Anode 7 segment display at once.

Project Name: 

Show 5 letters on 5 Common Anode 7 segment display at once.

Objective of Project: 

Creating a program to show the string “iubat” on 5 Common Anode 7 segment display.

Circuit Diagram:

List of components:

SL	Name and Description	Quantity
1	MCU 89C2051	1
2	7 segment display ( Common Anode )	5
3	Transistors NPN low power	5
4	Capacitors 30pf (10 uf 50Volt(1), 100uf 50Volt(1))	2
5	Crystal Q11.059A1	1
6	Voltage regulator 7805	1
7	Bread board	1
8	Connecting wires
9	Battery 9 Volt	1

Flowchart of program:

Printout of Program:

Brief Description of Program:

In this experiment, we will have to show “iubat” on 5 displays at once. That means it will show ‘i’ in CA0, ‘u’ in CA1, ‘b’ in CA2, ‘a’ in CA3 and‘t’ in CA4. That’s how we will see the “iubat”. For the program, we have similarities with the previous projects program. New concepts are there also in this program. Concept is that at a time we have to activate only one CA and show the character on it and the others must be deactivated. These activation deactivation process should be done so fast that we don’t recognize the movement of the characters one after another on different display. Then only we will be able to see “iubat”. So we know that CAs will be activated if we send 1(+5V) to the CA. Following this, in order to activate CA0 we have to send 1 to CA0 and send 0 to others. For that we need a 8 bit port register. We used the P3. We also need 5 NPN low power transistors. The emitters of the transistors are connected to the +5V and the collectors of the transistors are connected to the CAs sequentially. Then base of the 1st transistor is connected to P3.0, 2nd to P3.1, 3rd to P3.2, 4th to P3.3 and 5th to P3.4. So if we make P3.0 1 and others 0 which is in binary 00000001 and 01h in hex then CA0 will be activated. After that if we make 00000010 then the 2nd display will be activated. For doing this job in our program, we used the B register to store the value 01h by the instruction 

MOV B, #01h. And for shifting the bits, we have taken help of A register by the instruction    

RL A and then stored the value again in the B register with the help of the instruction MOV B, A and keep doing the process again and again.

What are the new concepts are given below:-

1. P1 register is used for the codes which are for displaying the characters on the display.
2. P3 register is used for activating a particular Common Anode at a time. We used the RL instruction for shifting the bits towards left so that CAs activate one after another.
3. We know that our eyes can memorize for 1/18 sec. Within this time if we change something we can’t recognize it. That is why we created our delay subroutine in such a way that it doesn’t take more than 1/18 sec for a single CA display. So, totally it will take for 5 CA display 1/90 sec.

Achievements (Result): 

So, it is showing “iubat” on 5 common anodes 7 segment display at once.

See the project at https://youtu.be/HRXQYlbZEKY