RELAY INTERFACING 8051

1. welcome

3. A RELAY IS AUTOMATICALLY CONTROLABLE
SWITCH.
IT IS HAVE THREE COMPONENTS,
o COIL
o SET OF CONTACTS

6. RELAY COIL IS CONTROL TO THE MICROCONTROLLER PINS.
IC 8051 KIT
DRIVER CIRCUIT, i.e (ULN2803)
OR
Power transistor
What is the purpose of driver circuit? Why?

8. • Relay coil energized needs
• But, IC 8051 microcontroller can provided maximum
range
10
mA
1-2 mA

9. IC
8051
DRIVER
CIRCUIT

12. • Main Program:
ORG 00H
HLT: SETB P1.0
MOV R5,#55
ACALL DELAY
CLR P1.0
MOV R5,#55
ACALL DELAY
SJMP HLT

13. Delay: MOV R4,#100
CCC: MOV R3,#253
BBB: DJNZ R3,AAA
AAA: DJNZ R4,BBB
DJNZ R5,CCC
RET
END

14. • MICRO OVEN
• Water pump control
• Industry motor control
• Home appliances