Microcontrollers Lecture Notes

Overview of Microcontrollers

• Microcontrollers are considered as single-chip computers.
• They include a CPU, memory, and peripheral interfaces.
• Notable microcontroller: 8051.

Key Features of 8051 Microcontroller

• Memory:
  • 4 KB ROM
  • 128 Bytes RAM
• I/O Ports: 4 ports, 8 bits each (32 bits total).
• Timers: 2 timers (16-bits each).
• Serial Interface: 1 serial communication port.

Architecture of the 8051 Microcontroller

• Includes essential modules: RAM, ROM, Timers, I/O Ports, and Serial Communication.
• The architecture is similar to that of a computer system but integrated into one chip.
• Overall benefits:
  • Reduced size of the system.
  • Increased speed due to on-chip connections.

Components of the Microcontroller

• CPU: Processes data and instructions.
• ROM: Stores the program code (fixed).
• RAM: Stores temporary data (read/write).
• I/O Ports: Required for external device communication.
• Timers/Counters: For precise timing and counting events.

Internal Structure of 8051

• Block Diagram Components:
  • 4 KB ROM
  • 128 Bytes RAM
  • 4 I/O Ports
  • 2 Timers
  • 1 Serial Port
• Additional Features:
  • Single on-chip oscillator
  • 6 interrupt sources (2 external, 3 internal)
  • Up to 64 KB external code and data memory (split)
  • Program Store Enable (PSEN) signal for ROM access.

Embedded Systems and Microcontrollers

• Microcontrollers are widely used in embedded systems (ex: washing machines, cars).
• They perform specific tasks and are integrated into larger systems.
• Task-oriented: Programs are typically fixed and burned onto ROM.
• Examples of applications include:
  • Automotive controls
  • Home appliances
  • Consumer electronics (e.g., mobile phones, cameras).

Choosing a Microcontroller

Criteria for Selection:

1. Performance Needs:
   • Speed of processing should meet task requirements.
   • Adequate ROM and RAM space.
2. I/O Ports:
   • Number of I/O ports needed for devices.
3. Timers:
   • Number of timers required for the application.
4. System Size & Power Consumption:
   • Consider package size and energy efficiency.
5. Upgrade Capability:
   • How easy it is to upgrade to higher performance versions.
6. Cost:
   • Cost per unit and overall system affordability.
7. Software Development Tools:
   • Availability of compilers, debuggers, etc.

Variants of the 8051 Microcontroller

• Variations exist such as:
  • 8031 (no internal ROM)
  • 8052 (additional timer)
• Higher series processors offer additional features like:
  • Flash memory
  • Watchdog timers for deadline monitoring.

Conclusion

• The 8051 microcontroller is a versatile option for embedded systems.
• Understanding the architecture and features is crucial for effective applications.
• Choosing the right microcontroller depends on application requirements and resource availability.