Interfacing of Hex Keypad and Seven Segment Display Using 8051 Microcontroller

Thread Starter

Ralf123

Joined Aug 16, 2014
10
Hey Guys!
Here is a situation.... I have been assigned a task to make a full adder connected to seven segment displays...........problem here is that I have to show both the Inputs and outputs on the ssds (its not restricted to show them at a time).... I have found a few circuits related to it.......but I am stuck at the beginning...I am working on proteus 8 professional....here is my circuit Its giving no error...but its not working!



 

bertus

Joined Apr 5, 2008
20,881
Hello,

Your resistors R1, R2 and R3 are much to large.
Try values between 1K and 10K for them.
Also I see no current limiting resistors on the segments of the displays.
Put resistors of 100 to 220 Ohms between the P1.X and the display segments.

Bertus
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
Thanks for your response :)
I have done the changes you said....now the display is on but the numbers donot change even after pressing the buttons of keypad!! have a look

 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
I think the problem is with the crystal oscillator i used the one named as X1 its value is 12MHz have a look maybe you get some hint!
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
Hello,

There is a program in the link I got from you in the PM:
http://ilabzelectronics.com/blog/in...-segment-display-using-8051-micro-controller/

Did you program the controller with that program?
As far as I understand, it will show the value typed on the keyboard on the display.

Bertus
Yes firstly when I ran the simulation in the software there were a number of errors like "could not load the program code" than i inserted the .asm file in the assembly source code of 89V51RD2..... After that there was no error with everything working smooth but the display on the ssds remained same they are not changing even after pressing the keys of the keypad!!!
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
Bertus
Is it possible to connect the two circuits??
Otherwise all of my efforts will be of no use....because basically what I am trying to do here is to make a Full adder and the display to be shown on ssds, also adding the keypad to enter input?
Thanks In advance!
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
Hello,

Is this a homework assignment?
Is it needed to use a microcontroller?

Here is a page from the EDUCYPEDIA on arithmetic circuits:
http://educypedia.karadimov.info/electronics/digitaarithmetic.htm

Bertus
Yes Its a kind of homework (more specifically a Project assigned).......I have to make it work practically but I will do that easily once the circuit starts working in proteus!

No there is no condition of using this micro controller... I am free to use anything.....
here is what is demanded....but the use of hex-pad is compulsory!

'Design and Implement a simple ALU (Arithmetic Logic Unit) with only ADDITION function. You have to display the digits and their results on a seven segment display".
 

THE_RB

Joined Feb 11, 2008
5,438
The matrixed keypad won't work properly unless you have pullup (or pulldown) resistors on 4 pins.

Do you understand how a matrixed keypad works in hardware and in the code?
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10
The matrixed keypad won't work properly unless you have pullup (or pulldown) resistors on 4 pins.

Do you understand how a matrixed keypad works in hardware and in the code?
Thanks for your Response :)
Sir can you be more specific where should I place the pullup resistors.....Is it on each of the 8 output terminals of the hex-pad?


No Sir I dont have any concepts related to the phenomenon of its working!
 

Thread Starter

Ralf123

Joined Aug 16, 2014
10

THE_RB

Joined Feb 11, 2008
5,438
This gives you an idea;



The resistors pull the column lines up to 5v when no buttons are pressed.

Then you take a row low to 0v, and check all 4 columns. This has to be repeated 4 times to read all 4 rows.

You need to understand the basic operation of the circuit AND the code operation, if you want to be successful making a project.
 
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