UNIT I — 8-BIT EMBEDDED PROCESSOR

8-Bit Microcontroller Architecture

8051 Microcontroller is an 8-bit microcontroller with on-chip RAM, ROM, I/O ports, timers, and serial communication.
It has:

4 KB on-chip ROM
128 bytes of RAM
32 I/O lines (4 ports – P0, P1, P2, P3)
2 timers (T0, T1)
1 serial port
5 interrupts

Block Diagram Components:

CPU – Executes instructions.
ALU – Performs arithmetic & logical operations.
Program Counter (PC) – Holds next instruction address.
Stack Pointer (SP) – Used for temporary storage.
Ports P0–P3 – Used for input/output operations.
Timers – Generate delays or count external events.
Serial Port – Used for data communication.

Instruction Set and Programming

8051 instructions are classified as:

Data Transfer Instructions (MOV, PUSH, POP)
Arithmetic Instructions (ADD, SUB, MUL, DIV)
Logical Instructions (AND, OR, NOT)
Branch Instructions (SJMP, LJMP, AJMP, CALL, RET)
Bit Manipulation Instructions (SETB, CLR, CPL, ANL)

Addressing Modes:

Immediate, Register, Direct, Indirect, Indexed

Programming Examples:

Delay Generation using timers
Addition / Multiplication / Division of numbers
Interrupt Handling and Serial Data Communication

Parallel Ports, Timers, Serial Port, and Interrupts

Parallel Ports: P0–P3 are bi-directional; used for I/O operations.
Timers: Two timers – T0 & T1, can operate in Mode 0 (13-bit), Mode 1 (16-bit), Mode 2 (8-bit auto-reload), Mode 3 (split-timer).
Serial Port: Used for serial communication (TXD, RXD).
Interrupts: 5 interrupt sources — two external, two timer, one serial.

UNIT II — EMBEDDED C PROGRAMMING

Memory and I/O Interfacing

8051 supports Program Memory (ROM) and Data Memory (RAM).
External EPROM or RAM can be interfaced using address/data bus and control signals (RD, WR, PSEN, ALE).

Memory Interfacing Techniques:

Linear decoding
Address latch enabling
Memory mapping

Programming Embedded Systems in C

Embedded C provides hardware control through low-level programming.

Supports keywords like bit, sbit, sfr for hardware registers.
Uses Keil Cx51 Compiler.
Example: Using sbit to define LED and switch pins.

Need for RTOS (Real-Time Operating System)

RTOS manages multiple tasks ensuring real-time response.
Features:

Predictable response time
Low interrupt latency
Task prioritization
Deterministic behavior

Components: Scheduler, Memory Management, Function Library, Fast dispatch latency.

Context Switching & Scheduling Policies

Context Switching: Saving CPU state when switching between tasks.
Scheduling Algorithms:

Preemptive Scheduling – High-priority tasks interrupt low-priority ones.
Non-preemptive Scheduling – Tasks run until completion.
Rate Monotonic Scheduling (RMS) – Fixed priority; shorter period = higher priority.
Earliest Deadline First (EDF) – Dynamic priority; nearest deadline = highest priority.

UNIT III — IoT AND ARDUINO PROGRAMMING

Concept of IoT Devices

IoT (Internet of Things) connects devices, sensors, and actuators via the internet to exchange data automatically.
IoT Components:

Sensors/Devices
Connectivity
Data Processing
User Interface

IoT Devices vs Computers

Parameter	IoT Devices	Computers
Purpose	Specific task	General purpose
Power	Low energy	High power
Storage	Limited	Large
Communication	Cloud-based	Local/Internet

Introduction to Arduino

Arduino is an open-source microcontroller platform used for IoT projects.

Based on ATmega microcontroller
Supports C/C++ programming
Controlled via Arduino IDE

Main Boards: Arduino UNO, Mega, Nano, LilyPad, Leonardo, Mini.
Main Components: USB Power, Analog/Digital Pins, PWM Pins, AREF, RESET, Voltage Regulator.

Arduino Toolchain

Includes compiler, assembler, linker, and libraries integrated in Arduino IDE for writing and uploading programs (called sketches).

Arduino Program Structure

setup() → executes once.
loop() → runs repeatedly.
Basic Functions:
pinMode()
digitalRead() / digitalWrite()
analogRead() / analogWrite()

Arduino Shields

Arduino Shields are plug-on modules expanding functionality (e.g., Ethernet, Motor, Wi-Fi shields).
They simplify sensor and actuator integration.

UNIT IV — IOT COMMUNICATION AND OPEN PLATFORMS

IoT Communication Models

Request-Response Model (HTTP)
Publish-Subscribe Model (MQTT)
Push-Pull Model
Exclusive Pair Model (WebSocket)

IoT Communication Protocols

Bluetooth / BLE – Short-range, low power.
Wi-Fi – High-speed, medium range.
ZigBee – Low power, mesh networking.
GPS – Global Positioning System for location tracking.
GSM – Cellular communication using SIM modules.

Open Platform — Raspberry Pi

Raspberry Pi is a low-cost single-board computer (SBC) with ARM processor (512MB–8GB RAM).
It supports Linux OS, GPIO interfacing, and cloud connectivity.

GPIO Pins: Can be programmed as input/output to control LEDs, sensors, and motors.

Steps to Access GPIO in Python:

Install GPIO library
Import library
Set pin mode
Setup input/output pin
Control with HIGH/LOW signals
Cleanup after use

UNIT V — UNIVERSAL APPLICATIONS DEVELOPMENT

Design of Embedded Systems

Embedded System Design integrates hardware and software for a specific function.
Steps:

Abstraction
Hardware–Software Architecture
System Mapping
User Interface Design
Refinement and Testing

Design Metrics: Performance, Power, Cost, Size, Maintainability, Time-to-market.

Development of IoT Applications

IoT Applications consist of four elements:

Cloud Technology
Dedicated Hardware
Reliable Network
Intuitive Software

Major IoT Applications

Smart Home
- Smart Lighting, Smart Appliances, Intrusion Detection, Smoke/Gas Sensors
Smart Agriculture
- Robotics, Drones, Smart Irrigation, Greenhouse Monitoring
Smart Cities
- Integration of digital, social, and physical infrastructure
Smart Healthcare
- Wearable sensors, remote monitoring, IoT-enabled medical devices

Here is UNIT I — 8-BIT EMBEDDED PROCESSOR in exam-oriented, simplified, and keyword-focused format based entirely on your uploaded IoT files (IOT1–IOT7 and UNIT-1.pdf).
All important terms are in bold, and key statements are made fully bold for concept clarity.

UNIT I – 8-BIT EMBEDDED PROCESSOR

1. Introduction to Microcontrollers

A Microcontroller is a compact integrated circuit designed to perform a specific task.
It contains a CPU, memory (RAM & ROM), I/O ports, timers, and serial communication interfaces all on a single chip.

Example: Intel 8051 Microcontroller, Motorola 6811, PIC 16X, etc.

2. Difference between Microprocessor and Microcontroller

Feature	Microprocessor	Microcontroller
Definition	General-purpose CPU	Single-chip computer for specific control tasks
Components	CPU only; external memory, I/O, timers required	On-chip CPU, RAM, ROM, I/O, timers, serial ports
Application	Used in computers and general-purpose systems	Used in embedded systems
System Design	Complex and expensive	Simple and cost-effective
Instruction Set	Complex	Simple
Example	Intel 8085, 8086	Intel 8051, PIC 16F877

3. Architecture of 8051 Microcontroller

The 8051 Microcontroller is an 8-bit embedded processor designed for control-based applications.

Salient Features of 8051

4 KB on-chip ROM (Program Memory)
128 bytes on-chip RAM (Data Memory)
8-bit CPU with 16-bit address bus
32 I/O lines divided into 4 ports (P0–P3)
Two 16-bit timers (T0, T1)
One full duplex serial port
Five interrupts (2 external, 2 timer, 1 serial)
One 16-bit Program Counter (PC) and one 8-bit Stack Pointer (SP)
Clock frequency = 12 MHz → 1 µs instruction cycle

Block Diagram Components

CPU (Central Processing Unit) – Executes instructions and controls system operations.
ALU (Arithmetic Logic Unit) – Performs arithmetic and logical operations.
Registers – Temporarily hold data for processing.
Program Counter (PC) – Holds the address of the next instruction.
Stack Pointer (SP) – Points to the top of the stack in RAM.
Timers/Counters – Used for delay generation and event counting.
I/O Ports (P0–P3) – Used for parallel input/output operations.
Interrupt Control – Manages internal/external interrupts.
Serial Port – Provides serial communication (TXD, RXD).
Oscillator and Clock Circuit – Provides system timing using crystal frequency.

Pin Configuration of 8051

8051 is a 40-pin IC with the following important pins:

Vcc (Pin 40): +5V power supply
GND (Pin 20): Ground
XTAL1 & XTAL2 (Pins 19 & 18): Connect to crystal oscillator
RST (Pin 9): Active-high reset input
PSEN (Pin 29): Program Store Enable (used for external ROM)
ALE (Pin 30): Address Latch Enable (demultiplexing lower address/data bus)
EA (Pin 31): External Access Enable
Ports:
- Port 0 (Pins 32–39): Multiplexed address/data bus
- Port 1 (Pins 1–8): Simple I/O port
- Port 2 (Pins 21–28): High-order address bus or I/O
- Port 3 (Pins 10–17): I/O or alternate functions (INT0, INT1, T0, T1, RXD, TXD, WR, RD)

4. Memory Organization of 8051

Types of Memory

Program Memory (ROM):
- Stores program code.
- 4 KB internal ROM.
- Can be extended externally up to 64 KB.
Data Memory (RAM):
- 128 bytes internal RAM.
- Divided into:
  - Register Banks (00H–1FH) → 4 banks, each with 8 registers.
  - Bit-Addressable Area (20H–2FH) → 16 bytes.
  - General Purpose RAM (30H–7FH) → Data storage area.
Special Function Registers (SFR):
- Upper 128 bytes (80H–FFH).
- Used for control and status registers like ACC, B, PSW, SP, DPH, DPL, TMOD, TCON, IE, IP, SCON, SBUF.

5. Programming 8051

Addressing Modes

Immediate Addressing – Data is part of the instruction.
MOV A, #45H
Register Addressing – Uses CPU registers.
MOV A, R0
Direct Addressing – Uses memory address.
MOV A, 30H
Indirect Addressing – Uses register pointer.
MOV A, @R0
Indexed Addressing – Used with DPTR for external memory.
MOVC A, @A+DPTR

Instruction Set Classification

Type	Examples
Data Transfer	MOV, PUSH, POP
Arithmetic	ADD, SUBB, INC, DEC
Logical	ANL, ORL, XRL, CPL
Branch	SJMP, LJMP, CALL, RET
Bit Manipulation	SETB, CLR, CPL, ANL, ORL

6. Timers and Counters

Timers in 8051

Timer 0 and Timer 1, both 16-bit registers.
Controlled using TMOD and TCON registers.

Timer Modes

Mode 0: 13-bit Timer (8192 counts)
Mode 1: 16-bit Timer (65536 counts)
Mode 2: 8-bit Auto Reload
Mode 3: Split Timer Mode

Example:

MOV TMOD, #01H    ; Timer 0, Mode 1
MOV TH0, #0FFH
MOV TL0, #0F2H
SETB TR0           ; Start Timer
AGAIN: JNB TF0, AGAIN
CLR TF0
CPL P1.0           ; Toggle output
SJMP AGAIN

This generates a square wave using Timer 0.

7. Serial Communication

8051 has one Full Duplex UART (TXD, RXD).
Baud rate generation uses Timer 1 in Mode 2.
Controlled by SCON and SBUF registers.
Modes:
1. Mode 0: Shift Register (Serial I/O)
2. Mode 1: 8-bit UART (Variable baud rate)
3. Mode 2: 9-bit UART (Fixed baud rate)
4. Mode 3: 9-bit UART (Variable baud rate)

8. Interrupt Handling

8051 has five interrupt sources:

INT0 (External Interrupt 0) – Pin P3.2
Timer 0 Overflow
INT1 (External Interrupt 1) – Pin P3.3
Timer 1 Overflow
Serial Communication Interrupt

Interrupt Control Registers

IE (Interrupt Enable Register): Enables/disables interrupts.
IP (Interrupt Priority Register): Sets interrupt priorities.

ISR (Interrupt Service Routine):

Executed automatically when an interrupt occurs.

Example:

ORG 0003H
LJMP ISR_EXT0
ORG 0030H
ISR_EXT0:
MOV P1, #0FFH
RETI

9. Programming Example for Interrupts

Objective: Flash Port 0 and Port 2 using two switches connected to P3.2 and P3.3.

Algorithm:

Enable interrupts using IE register.
Configure TCON for edge triggering.
Execute separate ISRs for each switch.

Registers Used: IE, TCON, EX0, EX1, IT0, IT1.

10. Summary

8051 Microcontroller is an 8-bit, single-chip computer used in embedded systems.
Contains CPU, memory, timers, serial ports, and interrupts on one chip.
Supports multiple addressing modes and rich instruction set.
Timers are used for delay generation and event counting.
Interrupts allow efficient task handling without polling.

✅ KEY POINTS TO REMEMBER (EXAM ORIENTED)

8051 = 8-bit data bus, 16-bit address bus
4 KB ROM, 128B RAM
5 Interrupts
4 I/O Ports
2 Timers (T0, T1)
1 Serial Port
12 MHz → 1 µs instruction cycle
Interrupts enable real-time control

Here’s your “Introduction to Embedded Systems” from UNIT I — 8-BIT EMBEDDED PROCESSOR, simplified and explained clearly using only your uploaded IoT sources (especially IOT1.pdf).
All keywords are in bold, and important exam points are in bold full statements.

Introduction to Embedded Systems

To make a complete microcomputer system, only a microprocessor is not sufficient.
It requires additional peripheral components such as:

Read-Only Memory (ROM)
Random Access Memory (RAM)
Decoders
Drivers
Input/Output (I/O) interfaces
Interrupt controllers
Programmable timers / counters

These external peripherals help the processor to store data, display results, and communicate with external devices.

However, to improve performance and reduce hardware complexity, all these essential components were later integrated on a single chip — this led to the development of the Microcontroller.

Microcontroller Overview

A Microcontroller is a single-chip microcomputer system that includes:

CPU (Microprocessor core)
ROM and RAM
Parallel and Serial I/O ports
Timers/Counters
Interrupt controller
Clock and timing circuit

Thus, a microcontroller is a self-contained control device capable of performing input, processing, and output operations without requiring external chips.

Advantages of Built-in Peripherals

Microcontrollers have built-in peripheral devices such as memory, I/O ports, and timers.
This provides several advantages:

Smaller access time → faster speed of operation.
Reduced hardware components → single-chip system.
Compact PCB size → increased reliability.
Lower system cost and better power efficiency.

Difference Between Microprocessor and Microcontroller

Feature	Microprocessor	Microcontroller
Definition	CPU only; needs external memory & peripherals	CPU + Memory + I/O + Timers on one chip
Components	ALU, Control Unit, Registers, Clock	Microprocessor core + Memory (ROM/RAM) + I/O + Timers + Serial/Parallel ports
Memory	External ROM/RAM	Built-in ROM and RAM
I/O Handling	Requires separate I/O devices	Has built-in I/O ports
Speed (Access Time)	Slower, due to external buses	Faster, due to on-chip memory
Hardware	Requires more hardware components	Requires less hardware, smaller PCB
Design Flexibility	More flexible for general computing	Optimized for dedicated control tasks
Pin Multiplexing	Fewer multifunction pins	More multifunction pins for I/O
Memory Map	Single memory space for code and data	Separate memory space for code and data
Examples	Intel 8085, 8086	Intel 8051, 8751, PIC 16F877

Features of 8051 Microcontroller

The 8051 is one of the most popular 8-bit microcontrollers developed by Intel.
It is optimized for control-oriented applications and single-bit Boolean operations.

Key Features

8-bit CPU with 8-bit data bus and 16-bit address bus
4 KB on-chip ROM (program memory)
128 bytes on-chip RAM (data memory)
Four Register Banks (R0–R7 × 4)
32 programmable I/O lines arranged as four 8-bit ports (P0–P3)
Two 16-bit timers/counters
Full duplex serial communication port
Five interrupt sources with two-level priority structure
64 KB program and data memory addressability (external)
1 µs instruction cycle at 12 MHz crystal frequency
Hardware multiply/divide unit (4 µs)
Direct byte and bit addressability
Built-in Boolean processor for logical operations
Compatible with Intel 8084 software

Benefits of Using 8051

Low-cost and widely available
Simple instruction set
High reliability for embedded control
Supported by many development tools

Conclusion

A microprocessor alone cannot operate as a complete system — it requires several external peripherals.
A microcontroller, on the other hand, integrates all required components (CPU, memory, I/O, timers, serial ports, etc.) on a single chip, making it ideal for embedded system applications.
The 8051 microcontroller is the most widely used 8-bit architecture due to its simplicity, efficiency, and built-in hardware features.

✅ Exam Points to Remember

Microcontroller = CPU + Memory + I/O + Timers on one chip
8051: 4 KB ROM, 128 B RAM, 32 I/O lines, 2 Timers, 5 Interrupts
Access Time (Microcontroller) < Access Time (Microprocessor)
Microcontrollers are best for control-based embedded systems

Introduction to Embedded Systems

To make a complete microcomputer system, only a microprocessor is not sufficient.
It requires additional peripheral components such as:

Read-Only Memory (ROM)
Random Access Memory (RAM)
Decoders
Drivers
Input/Output (I/O) interfaces
Interrupt controllers
Programmable timers / counters

These external peripherals help the processor to store data, display results, and communicate with external devices.

However, to improve performance and reduce hardware complexity, all these essential components were later integrated on a single chip — this led to the development of the Microcontroller.

Microcontroller Overview

A Microcontroller is a single-chip microcomputer system that includes:

CPU (Microprocessor core)
ROM and RAM
Parallel and Serial I/O ports
Timers/Counters
Interrupt controller
Clock and timing circuit

Thus, a microcontroller is a self-contained control device capable of performing input, processing, and output operations without requiring external chips.

Advantages of Built-in Peripherals

Microcontrollers have built-in peripheral devices such as memory, I/O ports, and timers.
This provides several advantages:

Smaller access time → faster speed of operation.
Reduced hardware components → single-chip system.
Compact PCB size → increased reliability.
Lower system cost and better power efficiency.

Difference Between Microprocessor and Microcontroller

Feature	Microprocessor	Microcontroller
Definition	CPU only; needs external memory & peripherals	CPU + Memory + I/O + Timers on one chip
Components	ALU, Control Unit, Registers, Clock	Microprocessor core + Memory (ROM/RAM) + I/O + Timers + Serial/Parallel ports
Memory	External ROM/RAM	Built-in ROM and RAM
I/O Handling	Requires separate I/O devices	Has built-in I/O ports
Speed (Access Time)	Slower, due to external buses	Faster, due to on-chip memory
Hardware	Requires more hardware components	Requires less hardware, smaller PCB
Design Flexibility	More flexible for general computing	Optimized for dedicated control tasks
Pin Multiplexing	Fewer multifunction pins	More multifunction pins for I/O
Memory Map	Single memory space for code and data	Separate memory space for code and data
Examples	Intel 8085, 8086	Intel 8051, 8751, PIC 16F877

Features of 8051 Microcontroller

The 8051 is one of the most popular 8-bit microcontrollers developed by Intel.
It is optimized for control-oriented applications and single-bit Boolean operations.

Key Features

8-bit CPU with 8-bit data bus and 16-bit address bus
4 KB on-chip ROM (program memory)
128 bytes on-chip RAM (data memory)
Four Register Banks (R0–R7 × 4)
32 programmable I/O lines arranged as four 8-bit ports (P0–P3)
Two 16-bit timers/counters
Full duplex serial communication port
Five interrupt sources with two-level priority structure
64 KB program and data memory addressability (external)
1 µs instruction cycle at 12 MHz crystal frequency
Hardware multiply/divide unit (4 µs)
Direct byte and bit addressability
Built-in Boolean processor for logical operations
Compatible with Intel 8084 software

Benefits of Using 8051

Low-cost and widely available
Simple instruction set
High reliability for embedded control
Supported by many development tools

Conclusion

A microprocessor alone cannot operate as a complete system — it requires several external peripherals.
A microcontroller, on the other hand, integrates all required components (CPU, memory, I/O, timers, serial ports, etc.) on a single chip, making it ideal for embedded system applications.
The 8051 microcontroller is the most widely used 8-bit architecture due to its simplicity, efficiency, and built-in hardware features.

✅ Exam Points to Remember

Microcontroller = CPU + Memory + I/O + Timers on one chip
8051: 4 KB ROM, 128 B RAM, 32 I/O lines, 2 Timers, 5 Interrupts
Access Time (Microcontroller) < Access Time (Microprocessor)
Microcontrollers are best for control-based embedded systems

Would you like me to continue with the next topic — Architecture of 8051 Microcontroller — in the same clear and exam-ready format?

Here is your 1-page quick revision for UNIT-I: 8-Bit Embedded Processor, prepared directly from your uploaded IoT sources (IOT1.pdf) — concise, exam-oriented, and with all key keywords highlighted for easy recall.

UNIT – I : 8-BIT EMBEDDED PROCESSOR – QUICK REVISION

1. Introduction

A Microprocessor alone is not sufficient to form a system – it needs memory, I/O, timers, decoders, and drivers.
A Microcontroller integrates all these components on a single chip, forming a self-contained microcomputer system.

Microcontroller = CPU + ROM + RAM + I/O + Timers + Serial Port + Clock.

2. Microprocessor vs Microcontroller

Feature	Microprocessor	Microcontroller
Components	CPU only	CPU + Memory + I/O + Timers
Memory	External	On-chip
Speed	Slower	Faster
Hardware	More hardware	Less hardware
Design	General purpose	Control specific
Example	8085, 8086	8051, 8751

3. Features of 8051 Microcontroller

8-bit CPU, 16-bit address bus
4 KB ROM, 128 B RAM, expandable to 64 KB each
4 I/O ports (P0–P3) – 32 bidirectional lines
2 Timers/Counters (16-bit)
1 Serial Port (Full Duplex UART)
5 Interrupts (2 external, 2 timer, 1 serial)
4 Register Banks (R0–R7 × 4)
1 µs instruction cycle @12 MHz
Hardware multiply/divide, Boolean processor, bit & byte addressable memory

4. 8051 Architecture Components

CPU / ALU – executes instructions.
Accumulator (A) – main register for arithmetic & logic.
B Register – used in multiply/divide.
DPTR (DPH + DPL) – 16-bit data pointer for external data.
Program Counter (PC) – holds next instruction address.
Stack Pointer (SP) – points to top of stack (starts at 07H).
PSW (Program Status Word) – flag register: CY, AC, OV, P, RS1, RS0.
Timers (T0, T1) – delay generation / counting.
Serial Port (TXD, RXD) – data communication.
Interrupt Controller – priority-based servicing.
Oscillator / Clock Circuit – timing source.

5. Memory Organization

Program Memory (ROM): 4 KB internal + up to 64 KB external.
Data Memory (RAM): 128 B internal
- 00H–1FH → Register Banks (4 banks)
- 20H–2FH → Bit-Addressable area (128 bits)
- 30H–7FH → General-Purpose RAM
SFRs (80H–FFH): Control registers (ACC, B, PSW, TCON, TMOD, SCON, SBUF, IE, IP).

6. Pin Configuration (40-Pin IC)

Vcc (40) – +5 V, GND (20) – ground
XTAL1/XTAL2 (18, 19) – crystal oscillator
RST (9) – reset
ALE (30) – address latch enable
PSEN (29) – program store enable
EA (31) – external access enable
Ports:
- P0 (32–39): AD0–AD7 (Address/Data)
- P1 (1–8): simple I/O
- P2 (21–28): high-order address or I/O
- P3 (10–17): I/O / alternate functions (INT0, INT1, T0, T1, RXD, TXD, WR, RD)

7. Timers and Counters

TMOD – mode control, TCON – start/stop & overflow flags
Modes:
- Mode 0 – 13-bit
- Mode 1 – 16-bit
- Mode 2 – 8-bit auto-reload
- Mode 3 – split timer
Used for delay generation and event counting.

8. Serial Communication

Controlled by SCON, data via SBUF.
Modes 0–3 for different baud rates.
Baud rate generated by Timer 1.

9. Interrupts

5 sources: INT0, T0, INT1, T1, Serial.
Controlled by IE (Enable) and IP (Priority).
Handled using ISR (Interrupt Service Routine).

10. Stack Operation

SP = 07H after reset → stack starts at 08H.
PUSH → SP increment, POP → SP decrement.
Used during CALL/RET and temporary data storage.

11. Important Numbers

Data bus: 8 bit
Address bus: 16 bit
I/O lines: 32
Clock: 12 MHz → 1 µs cycle
Interrupts: 5
Timers: 2
ROM: 4 KB internal + 64 KB external
RAM: 128 B internal + 64 KB external

12. Applications

Used in embedded control systems such as:

Home appliances
Traffic control
Data acquisition
Industrial automation
Robotics
Consumer electronics

✅ One-Line Summary:
8051 is a powerful 8-bit microcontroller integrating CPU, memory, I/O, timers, serial communication, and interrupt handling on a single chip – making it ideal for embedded control applications.

Would you like the next one-page revision for UNIT II – Embedded C Programming next?

Here’s your Study-Ready Revision Notes (Full Concepts – Easy to Learn, Step-by-Step)
for UNIT II – Instruction Set and Programming of 8051 — written like class notes for understanding and memorizing.

🧩 1. Addressing Modes of 8051

An addressing mode tells where the operand is located for an instruction. 8051 has six types:

Mode	Meaning	Example
Register Addressing	Operand in R0 – R7 of current bank	`MOV A, R5`
Direct Addressing	Gives RAM/SFR address in instruction	`MOV A, 30H`
Register Indirect	R0 or R1 contains RAM address	`MOV A, @R0`
Immediate	Operand is constant (‘#’ used)	`MOV A, #55H`
Indexed	A + DPTR/PC points code memory	`MOVC A,@A+DPTR`
Stack Addressing	Uses `PUSH`, `POP` with stack pointer	`PUSH 30H`

👉 On reset SP = 07H, so stack starts from address 08H upwards.

⚙️ 2. Classification of Instruction Set

Data Transfer ( MOV, MOVX, MOVC, XCH, PUSH, POP )
Arithmetic ( ADD, ADDC, SUBB, INC, DEC, MUL, DIV, DA A )
Logical (Byte / Bit level operations)
Rotate and Swap (RL, RLC, RR, RRC, SWAP A)
Branch and Call (Jumps, CALL, RET)

🗃️ 3. Data Transfer Instructions

Instruction	Function	Example
`MOV`	Copy data between registers	`MOV A, R0`
`MOVX`	Move to/from external RAM	`MOVX A,@DPTR`
`MOVC`	Read from code memory	`MOVC A,@A+DPTR`
`XCH`, `XCHD`	Exchange data	`XCH A, R1`
`PUSH / POP`	Store / Retrieve from stack	`PUSH 20H`

All external data moves through the accumulator A.

➕ 4. Arithmetic Instructions

Mnemonic	Operation	Example
`ADD`, `ADDC`	Add byte (with/without carry)	`ADD A, R2`
`SUBB`	Subtract with borrow	`SUBB A, @R1`
`INC / DEC`	Increment / Decrement	`INC R3`, `DEC A`
`MUL AB`	A×B → B:A (16-bit result)	`MUL AB`
`DIV AB`	A÷B → A=quotient, B=remainder	`DIV AB`
`DA A`	Decimal-adjust (BCD sum)	`DA A`

👉 Flags affected – CY, AC, OV in PSW.

💡 5. Logical Instructions

Byte Level: perform logic on whole bytes

ANL (AND), ORL (OR), XRL (XOR)
CLR A, CPL A (clear / complement accumulator)

Bit Level: operate on single bits (20H–2FH RAM + bit-addressable SFRs)

SETB bit (set to 1)
CLR bit (clear to 0)
CPL bit (toggle)
ANL C, bit, ORL C, bit, MOV C, bit

🔁 6. Rotate and Swap

Instruction	Effect
`RL A`	Rotate left
`RLC A`	Rotate left through carry
`RR A`	Rotate right
`RRC A`	Rotate right through carry
`SWAP A`	Exchange upper and lower nibbles

🧭 7. Branch / Jump / Call Instructions

Unconditional Jumps

SJMP label ( ±128 bytes )
AJMP addr11 (within 2 K block )
LJMP addr16 ( anywhere in 64 K )

Conditional Jumps

JZ, JNZ → Jump if A = 0 / ≠ 0
JC, JNC → Jump on carry set/clear
JB, JNB → Jump if bit = 1/0
DJNZ → Decrement and jump if not zero
CJNE → Compare and jump if not equal

Subroutines

ACALL / LCALL → Call routine
RET → Return
RETI → Return from interrupt

⏱ 8. Time Delay Concept

1 machine cycle = 12 oscillator periods
For 11.0592 MHz → 1 cycle = 1.085 µs

Example delay routine:

MOV R1,#30  
HERE: DJNZ R1,HERE

Delay ≈ (1 + 2×30)×1.085 µs ≈ 65 µs

🧮 9. Typical Assembly Examples

Add two numbers
MOV A,#25H ADD A,#12H
2’s complement
CPL A ADD A,#01H
Multiply two bytes MUL AB
BCD counter ADD A,#01H DA A
Find maximum using CJNE, JC loops

🧠 10. Important Points to Remember

All math/logic use Accumulator (A).
DPTR = 16-bit register for external addressing.
SP default = 07H, stack starts at 08H.
PSW controls register banks and flags.
Immediate data uses # symbol.
Every instruction executes in multiples of machine cycles (1 cycle ≈ 1 µs @ 12 MHz).

📝 Summary:
8051 has powerful instruction set supporting data transfer, arithmetic, logical, bit-manipulation, and branching.
It offers six addressing modes and assembly programs are built using these for I/O handling, looping, and delay generation in embedded applications.

Alright — here’s your detailed, easy-to-study full notes for UNIT II – 8051 Instruction Set and Programming, completely based on your syllabus and uploaded content.
This version is line-by-line conceptual explanation, suitable for study and writing in exams.

UNIT II – 8051 INSTRUCTION SET AND PROGRAMMING

1. INTRODUCTION

The instruction set of the 8051 defines all the operations the microcontroller can perform.
Each instruction tells the CPU what operation to perform, the data involved, and where to get or store that data.

Every instruction has:

Operation code (Opcode) – specifies what operation is to be done.
Operand(s) – specifies data, address, or register.

2. ADDRESSING MODES OF 8051

Addressing mode = the method of specifying operands in an instruction.

(a) Register Addressing Mode

The operand is stored in one of the registers R0–R7 of the currently selected bank.
Data moves between the accumulator and these registers.

Example:

MOV A, R3

→ Move contents of R3 to accumulator A.

Registers R0–R7 are in Bank 0 by default (address 00H–07H).
You can change bank using PSW register bits RS1, RS0.

(b) Direct Addressing Mode

The operand’s address in internal RAM or SFR is given directly in the instruction.
Access range: 00H–7FH (RAM) and 80H–FFH (SFR).

Example:

MOV A, 30H   ; Copy data from RAM location 30H to A
MOV 40H, A   ; Copy contents of A to location 40H

(c) Register Indirect Addressing Mode

R0 or R1 holds the address of the data in RAM.
Used for dynamic access to data (especially in loops).

Example:

MOV A, @R0   ; Copy data from address in R0 to A
MOV @R1, A   ; Copy data from A to address pointed by R1

Only R0 and R1 can be used for indirect addressing.

(d) Immediate Addressing Mode

Operand value is written in the instruction itself.
Uses symbol # before the value.

Example:

MOV A, #25H   ; Load 25H directly into A

Used for initializing registers or constants.

(e) Indexed Addressing Mode

Used to access program (code) memory using DPTR or PC.
The effective address = A + DPTR or A + PC.

Example:

MOVC A, @A+DPTR

→ Used for reading look-up table data stored in code memory (ROM).

(f) Stack Addressing Mode

Used with PUSH and POP instructions.
Operates using the Stack Pointer (SP) register.

Example:

PUSH 04H   ; Push contents of R4
POP 02H    ; Pop data into R2

On reset, SP = 07H, so the first PUSH stores data at address 08H.

3. CLASSIFICATION OF 8051 INSTRUCTION SET

Type	Examples	Purpose
1. Data Transfer	MOV, MOVX, MOVC, PUSH, POP, XCH	Transfer or exchange data
2. Arithmetic	ADD, ADDC, SUBB, INC, DEC, MUL, DIV, DA	Mathematical operations
3. Logical	ANL, ORL, XRL, CLR, CPL	Bitwise logic, masking
4. Bit-level (Boolean)	SETB, CLR, CPL, ANL C, ORL C	Single-bit control
5. Branch/Call	SJMP, LJMP, AJMP, CALL, RET	Program control and looping
6. Rotate/Swap	RL, RLC, RR, RRC, SWAP	Bit rotation operations

4. DATA TRANSFER INSTRUCTIONS

MOV (Move Instruction)

Transfers data from one place to another.

MOV A, R0       ; Register to A
MOV A, 30H      ; RAM to A
MOV 40H, A      ; A to RAM
MOV @R1, A      ; A to address in R1
MOV A, #55H     ; Immediate data to A

MOVX (Move External Data)

Used to transfer data between A and external memory.

MOVX A, @DPTR   ; Read data from external memory
MOVX @DPTR, A   ; Write data to external memory

MOVC (Move Code Memory)

Used to read data from program (ROM) memory.

MOVC A, @A+DPTR

PUSH / POP

Used with stack pointer for saving temporary data.

PUSH 30H
POP 30H

XCH / XCHD

Exchange data between registers or memory.

XCH A, R1       ; Exchange between A and R1
XCHD A, @R0     ; Exchange only lower nibbles

5. ARITHMETIC INSTRUCTIONS

Instruction	Operation	Example
ADD A, src	Add operand to A	`ADD A, #45H`
ADDC A, src	Add with carry	`ADDC A, R2`
SUBB A, src	Subtract with borrow	`SUBB A, 30H`
INC/DEC	Increment or decrement by 1	`INC R3`, `DEC A`
MUL AB	Multiply A×B (16-bit result in B:A)	`MUL AB`
DIV AB	Divide A/B (A=quotient, B=remainder)	`DIV AB`
DA A	Decimal adjust accumulator (BCD add)	`DA A`

Flags affected: CY (Carry), AC (Auxiliary Carry), OV (Overflow)

6. LOGICAL INSTRUCTIONS

Byte Level

Instruction	Example	Meaning
ANL	`ANL A,#0FH`	AND operation (mask bits)
ORL	`ORL A,40H`	OR operation (set bits)
XRL	`XRL A,R2`	XOR operation
CLR A		Clear accumulator
CPL A		Complement accumulator

Bit Level

Bit addressable area: RAM 20H–2FH and bit-addressable SFRs.

Instruction	Meaning
SETB bit – Set bit = 1	`SETB P1.2`
CLR bit – Clear bit = 0	`CLR P1.2`
CPL bit – Complement bit	`CPL P1.2`
ANL C, bit – AND carry with bit
ORL C, bit – OR carry with bit
MOV C, bit – Move bit to carry

7. ROTATE AND SWAP INSTRUCTIONS

Instruction	Function	Description
RL A	Rotate Left	Moves bit 7 → bit 0
RLC A	Rotate Left through Carry	Bit 7 → CY, CY → bit 0
RR A	Rotate Right	Bit 0 → bit 7
RRC A	Rotate Right through Carry	Bit 0 → CY, CY → bit 7
SWAP A	Swap nibbles	Upper 4 bits ↔ Lower 4 bits

8. BRANCH AND CALL INSTRUCTIONS

Jump Instructions

Change program flow.

Type	Mnemonic	Range	Description
Short Jump	`SJMP label`	±128 bytes	Short range jump
Absolute Jump	`AJMP addr11`	2 KB	Within same block
Long Jump	`LJMP addr16`	64 KB	Anywhere in memory
Conditional Jump	`JZ`, `JNZ`, `JC`, `JNC`, `JB`, `JNB`, `CJNE`, `DJNZ`	—	Based on flags or bit

Example:

JZ LABEL  ; Jump if accumulator = 0
DJNZ R0, LOOP  ; Decrement R0 and jump if not 0

Call and Return

Used for subroutines.

Instruction	Description
ACALL addr11	Call within 2 KB block
LCALL addr16	Call anywhere in memory
RET	Return from subroutine
RETI	Return from interrupt service routine

9. TIME DELAY GENERATION

Time delay depends on crystal frequency and instruction cycles.

1 machine cycle = 12 oscillator periods.
For 11.0592 MHz → 1 cycle = 1.085 µs

Delay Formula:

Delay = (No. of machine cycles × 1.085 µs)

Example:

MOV R1, #30
HERE: DJNZ R1, HERE

→ Each loop ≈ 69.4 µs delay.

10. SAMPLE PROGRAMS

(i) Add two numbers

MOV A,#30H
ADD A,#50H

(ii) Find 2’s complement

MOV A, R0
CPL A
ADD A, #01H

(iii) Multiply two numbers

MOV A,#05H
MOV B,#03H
MUL AB

(iv) Generate BCD up-counter

MOV A,#00H
BACK: MOV P1,A
ADD A,#01H
DA A
SJMP BACK

(v) Find maximum of 10 numbers

MOV DPTR,#2000H
MOV R0,#0AH
MOV R3,#00H
AGAIN: MOVX A,@DPTR
CJNE A,R3,NE
AJMP SKIP
NE: JC SKIP
MOV R3,A
SKIP: INC DPTR
DJNZ R0,AGAIN

11. IMPORTANT REGISTERS

Register	Function
A (Accumulator)	Arithmetic & logic operations
B	Used in MUL, DIV
DPTR (DPL, DPH)	16-bit data pointer for external memory
PSW	Flags & register bank selection
SP	Stack pointer (default 07H)
PC	Program counter
CY, AC, OV	Flag bits for arithmetic

12. KEY FORMULAS AND CONCEPTS

Machine Cycle Time = 12 / fosc
Delay = (No. of machine cycles × cycle time)
SP rolls over from FFH → 00H after stack overflow.
Bit-addressable RAM: 20H–2FH → 128 bits.
SFR area: 80H–FFH (TCON, SCON, P0–P3, PSW, ACC, B, etc.)

13. KEY FEATURES OF 8051 PROGRAMMING

All operations centered on Accumulator (A).
Data movement between A and registers or memory.
Flexible addressing modes simplify data access.
Boolean processor supports single-bit operations.
Timers and interrupts can be controlled by assembly instructions.

✅ Summary
The 8051 Instruction Set provides a complete set of instructions for:

Data transfer
Arithmetic and logic processing
Bit manipulation
Program control and delay generation.

Understanding these allows you to write assembly programs for all embedded control applications, from simple I/O toggling to real-time data processing.

Would you like me to continue with the next detailed notes – UNIT III (Parallel Ports, Timers, Serial Port & Interrupts) in the same structured style?

Here’s a detailed, exam-ready full explanation for “Parallel Ports, Timers, Serial Port, and Interrupts of 8051” (UNIT – III) — based completely on your uploaded textbook.
This is theoretical + programming + diagrams in words — formatted for writing answers and easy studying.

UNIT – III: Parallel Ports, Timers, Serial Port, and Interrupts

3.1 – 8051 I/O PORTS STRUCTURE

The 8051 microcontroller has 4 parallel I/O ports (P0, P1, P2, P3) each with 8 pins, totaling 32 I/O lines.
Each port can be used as input or output, depending on the program.

PORT 0 (Pins 32–39)

Functions as a dual-purpose port:
- I/O port (when used internally)
- Address/data bus (AD0–AD7) when external memory is accessed.
Open drain output → requires external pull-up resistors (10 kΩ) for normal I/O operation.
Used as multiplexed address/data bus in external memory interfacing.

Control Diagram:

Internal bus → Latch → Output driver → P0.x Pin

Special Use: Lower-order address/data bus (AD0–AD7).

PORT 1 (Pins 1–8)

Simple I/O port, used only for input/output.
Internally pulled-up, no external resistor needed.
Each pin can directly drive TTL logic devices.

Use Example: Connecting LEDs, switches, sensors.

PORT 2 (Pins 21–28)

Dual function:
- As I/O port
- As high-order address bus (A8–A15) when external memory is accessed.
Has internal pull-ups.
When used as address bus, values from P2 provide high-byte of address.

PORT 3 (Pins 10–17)

Multi-functional port:
- Can be used as I/O or for special alternate functions.

Pin	Alternate Function	Description
P3.0	RXD	Serial input
P3.1	TXD	Serial output
P3.2	INT0	External interrupt 0
P3.3	INT1	External interrupt 1
P3.4	T0	Timer 0 external input
P3.5	T1	Timer 1 external input
P3.6	WR	External memory write
P3.7	RD	External memory read

Key Points

All ports are bit and byte addressable.
On reset, all ports are configured as inputs (logic 1).
To use as output, load ‘0’ to output latch.

3.2 – I/O BIT MANIPULATION PROGRAMMING

Key Points

Port 0 requires external pull-ups for input/output.
Ports 1, 2, 3 have internal pull-ups.
To make a port input, write FFH to it.
To make a port output, write data directly.

Example Programs

1. Toggle all bits of Port 0 continuously

BACK: MOV A, #0AAH
MOV P0, A
ACALL DELAY
MOV A, #55H
MOV P0, A
ACALL DELAY
SJMP BACK

2. Read P1 and send to P2

MOV A, #0FFH
MOV P1, A
MOV A, P1
MOV P2, A

3. Test input bit and output data

SETB P1.5
JNB P1.5, SKIP
MOV P0, #35H
SKIP: SJMP SKIP

3.3 – 8051 TIMERS

Introduction

8051 has two 16-bit timers/counters: Timer 0 and Timer 1.
Used for time delay generation, event counting, and baud rate generation.

Timer Registers:

TH0, TL0 → Timer 0 High/Low byte
TH1, TL1 → Timer 1 High/Low byte

TMOD – Timer Mode Register

Bit	Name	Function
7	GATE	Control via external INTx
6	C/T	0 = Timer, 1 = Counter
5–4	M1, M0	Mode select for Timer 1
3	GATE	Same as above for Timer 0
2	C/T	Same for Timer 0
1–0	M1, M0	Mode select for Timer 0

Timer Modes:

Mode	Type	Description
0	13-bit timer	TLx = 5 bits, THx = 8 bits
1	16-bit timer	Full 16-bit count
2	8-bit auto reload	TLx overflows → reloads from THx
3	Split timer mode	TL0 and TH0 act as two separate 8-bit timers

TCON – Timer Control Register

Bit	Name	Function
7	TF1	Timer 1 overflow flag
6	TR1	Timer 1 run control
5	TF0	Timer 0 overflow flag
4	TR0	Timer 0 run control
3–0	IE1, IT1, IE0, IT0	External interrupt bits

3.4 – TIMER MODES AND PROGRAMMING

Mode 0 – 13-bit Timer

TLx = 5 bits, THx = 8 bits
Used rarely, backward-compatible.

Mode 1 – 16-bit Timer

THx and TLx form 16-bit counter.
Overflow at 65536 → TFx = 1.

Steps to program:

Load TMOD.
Load THx and TLx.
Start timer (SETB TRx).
Wait for overflow flag TFx.
Stop timer and clear flag.

Example: Generate Delay

MOV TMOD, #01H
MOV TH0, #0FFH
MOV TL0, #0A0H
SETB TR0
HERE: JNB TF0, HERE
CLR TR0
CLR TF0

Mode 2 – 8-bit Auto Reload

TLx counts; when overflow occurs, TLx reloads from THx automatically.
Used for periodic tasks and baud rate generation.

Mode 3 – Split Timer Mode

Timer 0 split into two 8-bit timers (TH0 and TL0).
Timer 1 stops.

3.5 – COUNTER PROGRAMMING

8051 timers can also act as event counters by using external pins:
- T0 → P3.4
- T1 → P3.5

Select Counter Mode:
Set C/T = 1 in TMOD register.

Example: Counter 1 Mode 2

MOV TMOD, #01100000B
MOV TH1, #00H
SETB P3.5
SETB TR1
BACK: MOV A, TL1
MOV P2, A
JNB TF1, BACK

3.6 – SERIAL PORT

Features

Full Duplex (can send and receive simultaneously)
Registers used: SBUF, SCON, PCON
Pins: P3.0 (RXD), P3.1 (TXD)

SCON – Serial Control Register

Bit	Name	Description
7	SM0	Serial mode bit 0
6	SM1	Serial mode bit 1
5	SM2	Multiprocessor bit
4	REN	Receive enable
3	TB8	Transmit bit 8
2	RB8	Receive bit 8
1	TI	Transmit interrupt flag
0	RI	Receive interrupt flag

Serial Communication Modes

Mode	Bits	Baud Rate	Function
0	8	Fixed (fosc/12)	Shift Register
1	10	Variable	UART (Start + 8 data + Stop)
2	11	Fixed (fosc/64 or fosc/32)	UART with 9-bit data
3	11	Variable	Same as Mode 2

PCON – Power Control Register

| Bit | Name | Function |
|:--|:--|
| 7 | SMOD | Doubles baud rate |
| 1 | PD | Power down |
| 0 | IDL | Idle mode |

Baud Rate Formula

For Timer 1 in Mode 2:
[
TH1 = 256 - \frac{(Oscillator Frequency)}{384 × Baud Rate}
]

Example (11.0592 MHz, 9600 baud):
[
TH1 = 256 - \frac{11059200}{384 × 9600} = FDH
]

Example: Transmit “A” Continuously

MOV TMOD, #20H
MOV TH1, #FDH
MOV SCON, #50H
SETB TR1
AGAIN: MOV SBUF, #'A'
HERE: JNB TI, HERE
CLR TI
SJMP AGAIN

3.7 – INTERRUPT STRUCTURE

Interrupt Sources in 8051

INT0 – External interrupt 0
T0 – Timer 0 overflow
INT1 – External interrupt 1
T1 – Timer 1 overflow
Serial – RI or TI flags

Interrupt Enable Register (IE)

Bit	Name	Function
7	EA	Enable all interrupts
6	–	Reserved
5	ES	Enable serial interrupt
4	ET1	Enable Timer 1
3	EX1	Enable INT1
2	ET0	Enable Timer 0
1	EX0	Enable INT0
0	–	—

Interrupt Priority Register (IP)

Sets high/low priority for each interrupt.
High priority interrupts can interrupt low ones.

Interrupt Vector Table

Interrupt	Vector Address	Priority
External INT0	0003H	Highest
Timer 0	000BH	2
External INT1	0013H	3
Timer 1	001BH	4
Serial Port	0023H	Lowest

Example: Enable Timer 0 Interrupt

SETB EA
SETB ET0

Example: Timer Interrupt ISR

ORG 000BH
CPL P1.0
RETI
ORG 0030H
MOV TMOD, #02H
MOV TH0, #1AH
MOV IE, #82H
SETB TR0
HERE: SJMP HERE

✅ Summary

Unit Component	Purpose
Ports	Interface digital I/O devices
Timers/Counters	Generate delays, count external events
Serial Port	UART communication with PC/Devices
Interrupts	Efficient handling of multiple tasks

This is the complete UNIT III (Parallel Ports, Timers, Serial Port & Interrupts) — clear, formatted, and directly exam-oriented.

Would you like the next detailed notes (UNIT IV – IoT Communication & Open Platforms) in the same structured, textbook-aligned style?

General study

8-Bit Microcontroller Architecture

Instruction Set and Programming

Parallel Ports, Timers, Serial Port, and Interrupts

UNIT II — EMBEDDED C PROGRAMMING

Memory and I/O Interfacing

Programming Embedded Systems in C

Need for RTOS (Real-Time Operating System)

Context Switching & Scheduling Policies

UNIT III — IoT AND ARDUINO PROGRAMMING

Concept of IoT Devices

IoT Devices vs Computers

Introduction to Arduino

Arduino Toolchain

Arduino Program Structure

Arduino Shields

UNIT IV — IOT COMMUNICATION AND OPEN PLATFORMS

IoT Communication Models

IoT Communication Protocols

Open Platform — Raspberry Pi

UNIT V — UNIVERSAL APPLICATIONS DEVELOPMENT

Design of Embedded Systems

Development of IoT Applications

Major IoT Applications

UNIT I – 8-BIT EMBEDDED PROCESSOR

1. Introduction to Microcontrollers

2. Difference between Microprocessor and Microcontroller

3. Architecture of 8051 Microcontroller

Salient Features of 8051

Block Diagram Components

Pin Configuration of 8051

4. Memory Organization of 8051

Types of Memory

5. Programming 8051

Addressing Modes

Instruction Set Classification

6. Timers and Counters

Timers in 8051

Timer Modes

7. Serial Communication

8. Interrupt Handling

Interrupt Control Registers

ISR (Interrupt Service Routine):

9. Programming Example for Interrupts

10. Summary

Introduction to Embedded Systems

Microcontroller Overview

Advantages of Built-in Peripherals

Difference Between Microprocessor and Microcontroller

Features of 8051 Microcontroller

Key Features

Benefits of Using 8051

Conclusion

Introduction to Embedded Systems

Microcontroller Overview

Advantages of Built-in Peripherals

Difference Between Microprocessor and Microcontroller

Features of 8051 Microcontroller

Key Features

Benefits of Using 8051

Conclusion

UNIT – I : 8-BIT EMBEDDED PROCESSOR – QUICK REVISION

1. Introduction

2. Microprocessor vs Microcontroller

3. Features of 8051 Microcontroller

4. 8051 Architecture Components

5. Memory Organization

6. Pin Configuration (40-Pin IC)

7. Timers and Counters

8. Serial Communication

9. Interrupts

10. Stack Operation

11. Important Numbers

12. Applications

🧩 1. Addressing Modes of 8051

⚙️ 2. Classification of Instruction Set

🗃️ 3. Data Transfer Instructions

➕ 4. Arithmetic Instructions

💡 5. Logical Instructions

🔁 6. Rotate and Swap