K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
Course Name:
Electro-Mechanical Systems
Semester:
V
Date of Performance: 27/08/2021
Batch No:
A1
Faculty Name:
Roll No:
1912017
Prof. Sandeep Hanumante
Faculty Sign & Date:
Grade/Marks:
Experiment No: 3
Title: Interfacing of Hex-keypad with 8051 microcontroller.
Aim and Objective of the Experiment:
• Interface Hex-key pad using Hex-key pad controller (74922) at PORT1 of 8051 microcontroller.
COs to be achieved:
CO1: Identify and describe the key elements of electro-mechanical system.
CO2: Design microcontroller based industrial applications.
CO3: Understand the principles of various electric actuator systems.
Theory:
In this experiment we used 8051 microcontroller, IC 74922(keypad controller IC), 7 segment display
(common anode) and a hex keypad.
Connections:
1. We have to connect the hex keypad with the IC 74922 through bus. Then connect the A, B,
C and D terminal of IC74922 to 8051 microcontroller port pins P1.0, P1.1, P1.2, P1.3
respectively.
2. Connect KBM of IC 74922 to ground through a 100uF capacitor and OSC to ground through
10uF capacitor.
3. Connect DA of IC 74922 to pin P3.2.
4. Connect OE* to P1.7.
5. Connect common anode 7 segment display to 8051 microcontroller.
So, after uploading the .hex file, as soon as a button on hex keypad is pushed and released the
respective HEX number will be displayed on the 7-segment display.
EMS Lab
Semester: V
Academic Year: 2021-2022
K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
Circuit Diagram/ Block Diagram:
Stepwise-Procedure:
1. Design circuit and connect it as shown in the circuit diagram using Proteus simulator.
2. Write an Embedded-C program to achieve the aim.
3. Compile the program and generate HEX file using Keil microvision-3 IDE.
4. Run the hardware and take scree shot of it to attach in the output.
Embedded-C program:
C51 COMPILER V9.60.0.0 HEX_PAD
PAGE 1
08/27/2021 17:11:56
C51 COMPILER V9.60.0.0, COMPILATION OF MODULE HEX_PAD
OBJECT MODULE PLACED IN .\Objects\hex_pad.obj
COMPILER INVOKED BY: C:\Keil_v5\C51\BIN\C51.EXE hex_pad.c OPTIMIZE(8,SPEED)
EMS Lab
Semester: V
Academic Year: 2021-2022
K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
BROWSE DEBUG OBJECTEXTEND PRINT(.\Listings\h
-ex_pad.lst) TABS(2) OBJECT(.\Objects\hex_pad.obj)
line level
source
1
#include <reg52.h>
2
#include <intrins.h>
3
#define kbdport P1
4
sbit kbd_en=P1^7;
5
sbit int_0=P3^2;
6
void isrint0(void);
7
unsigned char keycode;
8
unsigned
char
ss_code[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x98,0x88,0x83,0xc6,0xa1,0x86,0x8e};
9
10
void isrint0(void) interrupt 0
11
{
12 1
kbd_en=0;
13 1
keycode=kbdport;
14 1
keycode=keycode&0x0f;
15 1
kbd_en=1;
16 1
P2=ss_code[keycode];
17 1
}
18
19
20
21
void main(void)
22
{
23 1
SP=0x50;
24 1
kbdport=0x0f;
25 1
kbd_en=1;
26 1
int_0=1;
27 1
IE=0x81;
28 1
IT0=1;
29 1
last: goto last;
30 1
}
MODULE INFORMATION: STATIC OVERLAYABLE
CODE SIZE
= 51 ---CONSTANT SIZE = ---- ----
EMS Lab
Semester: V
Academic Year: 2021-2022
K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
XDATA SIZE
= ---- ---PDATA SIZE
= ---- ---DATA SIZE
= 17 ---IDATA SIZE
= ---- ---BIT SIZE
= ---- ---END OF MODULE INFORMATION.
C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S)
EMS Lab
Semester: V
Academic Year: 2021-2022
K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
Observation Table/Output snap of program:
EMS Lab
Semester: V
Academic Year: 2021-2022
K. J. Somaiya College of Engineering, Mumbai-77
(A Constituent College of Somaiya Vidyavihar University)
Department of Electronics Engineering
Post Lab Subjective/Objective type Questions:
1. What is disadvantage of interfacing Hex-key pad without key-pad controller?
Answer: IC 74922 is used as a key-pad controller in above experiment. Generally, microcontroller
have limited number of input/ output pins so by connecting the hex keypad directly with the
microcontroller would require 8 I/O pins. But by using the key-pad controller IC the no of pins used
reduces to only 4 i.e.by using keypad controller would save I/O pins. The key-pad controller is also
used to interrupt the microcontroller.
Conclusion:
In this experiment we learned how to us a keypad controller to interface a Hex keypad to 8051
microcontroller and display the respective key press on hex keypad on to a 7 segment display.
Signature of faculty in-charge with Date:
EMS Lab
Semester: V
Academic Year: 2021-2022