The document discusses the 8051 microcontroller, including its architecture, pin configuration, memory organization, timers, interrupts, and interfacing capabilities. It describes the 8051's features like on-chip RAM, ROM, timers and low power consumption which make it suitable for control applications. The document outlines the differences between microprocessors and microcontrollers, and covers various interfacing examples like switches, LEDs, 7-segment displays, LCDs, ADCs and relay interfacing. It concludes with common applications of the 8051 such as in automobiles, industrial processing, robotics and consumer electronics.

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2. CONTENTS
• Introduction.
• Microcontroller vs Microprocessor.
• Architecture.
• Pin diagram.
• Pin configuration.
• Memory Organisation.
• Timers.
• Interrupts.
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3. • Serial Communication.
• Interfacing.
a) +5 volt power supply.
b) switch interfacing.
c) LED interfacing.
d) 7-Segment display interfacing.
e) LCD interfacing.
f) ADC interfacing.
g) keypad interfacing.
h) relay interfacing.
• Applications.
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4. INTRODUCTION
• A single chip computer or A CPU with all
the peripherals like RAM, ROM, I/O, Timers,
ADCs, etc on the same chip.
OR
• A microcontroller is meant to be more self-
- contained and independent, and functions
as a tiny, dedicated computer.
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5. FEATURES OF 8051
• useful for small computing tasks.
• adequate for many control and monitoring
application.
• packaging(RAM,ROM,Timers on-chip).
• Less power consumption.
• Easily upgradable.
• Cost per unit is less.
• Availability of tools of microcontroller
such as proteus(simulator) and keil(compiler).
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6. MICROPROCESSOR vs
• General purpose device.
• do not contain on-chip
I/O ports, Timers, ADC
Memory etc.
• used as CPU in computer.
• design is complex and
expensive.
• it has zero status flag.
MICROCONTROLLER
• single chip computer.
• it includes RAM ,ROM
,Timers, ADC, DAC,
interrupts etc.
• performs control oriented
applications.
• simple and less expensive
• it has no zero flag.
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7. TYPES OF ARCHITECTURES
1) Von-Neumann Architecture
 only one bus.
 used for both data transfer and instruction fetches.
 cannot be performed at same time.
2) Harvard Architecture
 Separate data and instruction buses.
 Transfers to be performed simultaneously on both
buses.
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8. ARCHITECTURE
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9. PIN DIAGRAM
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10. PIN CONFIGURATION
 ALE/PROG-: when this pin is high it latches the
low byte of the address during accesses to external
memory. This pin is low during EPROM
programming.
 PSEN-: Program Store Enable is the read strobe to
external program memory.
 EA/VPP-: This pin is an active low pin connected
to ground when microcontroller is accessing the
program code stored in the external memory and
connected to Vcc when it is accessing the program code
in the on chip memory.
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11. PIN CONFIGURATION
 RST -: applying a high pulse to this pin, the
microcontroller will reset and terminate all activities.
 PORT 0 to 3 -: These are 8-bit bidirectional I/O
port. Port 0 does not contain any internal pull-ups.
Alternate function of port 3are RxD, TxD, INT0,
INT1,T0,T1,WR,RD.
 XTAL1 & XTAL2 -: connected to oscillator
amplifier.
 VCC-: Supply voltage.
 VSS-: Circuit ground potential.
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12. MEMORY ORGANISATION
• Code Memory.
• External RAM.
• On-Chip Memory.
• Internal RAM.
• Special Function Register.
• Machine Cycle.
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13. Code Memory
 holds the actual 8051 program.
 limited to 64K.
 may be both internal or external.
External RAM
 slow accessing speed.
 it gains in quantity.
 limited to 64K.
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14. On-Chip Memory
 It refers to that memory that physically exists
on the microcontroller itself.
 Two types-
a) Internal RAM.
b) SFR(Special Function Register.)
 Total 256 bytes.
 Equal memory for RAM and SFR i,e 128bytes.
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16. SPECIAL FUNCTION REGISTER
 Accumulator.
 B Register.
 Program Status Word.
 Stack Pointer.
 Data Pointer.
 Ports 0 to 3.
 Timer Registers.
 Control Register.
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17. +5 VOLT POWER SUPPLY
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18. SWITCH INTERFACING
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19. LED INTERFACING
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20. 7 SEGMENT INTERFACING
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21. LCD INTERFACING
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22. RELAY INTERFACING
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23. ADC INTERFACING
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24. MATRIX KEYPAD INTERFACING
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25. APPLICATION OF 8051
 Automobile.
 Rail Transport.
 Industrial Processing.
 Remote sensing.
 Robotics.
 Consumer electronics.
 Security(e-commerce and smart cards).
 Medical.
 Defense application.
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