Pin Diagram of 8051 Microcontroller - 8051 Microcontroller - Microcontroller and Its Applications

Summary

In this video, the 8051 microcontroller's pin diagram and its functionality are thoroughly explained. It covers the role of its 40 pins, divided into ports for input/output tasks and specialized functions like serial communication, external memory interfacing, and power supply. The 8051 is an 8-bit microcontroller, with ports multiplexed to manage both address and data buses, and pins assigned for interrupts, timers, and reset functionality. The video is an in-depth guide for anyone looking to understand how the 8051 microcontroller's pinout works in various applications.

Takeaways

• 😀 The 8051 microcontroller is an 8-bit, general-purpose microcontroller, available in a 40-pin DIP IC format.
• 😀 It features 32 input/output pins, divided into four ports: Port 0, Port 1, Port 2, and Port 3, with each port having 8 bits.
• 😀 Port 0 serves as both a general-purpose I/O port and a multiplexed address/data bus when external memory is used.
• 😀 Port 1 is a simple 8-bit bi-directional I/O port, with no dual function assignments.
• 😀 Port 2 acts as a general-purpose 8-bit I/O port and as the higher-order address bus when external memory is in use.
• 😀 Port 3 has multiple functions including I/O, serial communication (transmit/receive), interrupts, and timer inputs.
• 😀 The reset pin (Pin 9) resets the internal registers of the microcontroller when it is held high for two machine cycles.
• 😀 The crystal pins (Pins 18 and 19) are used to connect a crystal oscillator, providing the clock signal to the microcontroller.
• 😀 Pins 20 and 40 are used for power connections: Pin 20 for ground and Pin 40 for +5V supply.
• 😀 Special pins such as PSE (Program Store Enable), ALE (Address Latch Enable), and EA (External Access) manage memory interfacing for external memory modules.
• 😀 The microcontroller requires a +5V supply and consumes around 500mA of current for proper operation, though lower power versions exist.

Q & A

What is the 8051 microcontroller?

The 8051 is an 8-bit microcontroller, one of the most popular general-purpose microcontrollers, available in a 40-pin DIP (Dual Inline Package) IC. It can handle 8-bit operations and has a 16-bit address bus, making it suitable for a variety of applications.

What are the main features of the 8051 microcontroller's pins?

The 8051 microcontroller has 40 pins, with 32 of them serving as input/output (I/O) pins. These are divided into four 8-bit ports (Port 0, Port 1, Port 2, and Port 3), each having multiple functions including general I/O operations, addressing, and communication.

What does Port 0 of the 8051 microcontroller do?

Port 0 is an 8-bit general-purpose I/O port. It also functions as the lower-order address and data bus when external memory is used. When no external memory is present, it serves as a standard I/O port.

How does Port 1 differ from the other ports on the 8051 microcontroller?

Port 1 is a dedicated bi-directional 8-bit I/O port with no multiplexed functions. Unlike Ports 0, 2, and 3, which have dual functions, Port 1 is used purely for general-purpose input/output tasks when interfacing with external devices.

What additional functions does Port 3 provide?

Port 3 provides eight pins that can be used as general I/O ports. However, it also serves additional functions such as serial communication (TXD/RXD), external interrupts (INT0/INT1), and inputs for timers and counters (T0/T1).

What is the function of the Reset pin on the 8051 microcontroller?

The Reset pin (pin 9) is used to reset the internal registers of the 8051 microcontroller. When held high for two machine cycles, it clears all registers and sets them to their initial state, essentially restarting the microcontroller.

How does the crystal oscillator work with the 8051 microcontroller?

The 8051 microcontroller uses an external crystal connected to pins 18 and 19 to generate the clock frequency. The crystal provides the clock pulses necessary for the microcontroller's internal operations, such as timing and control signals.

What role does the Program Store Enable (PSEN) pin play in the 8051 microcontroller?

The PSEN pin is used to access external program memory. It is an active-low signal, meaning it is activated when a low voltage is applied. This signal is crucial for reading data from the external program memory.

What is the function of the Address Latch Enable (ALE) pin?

The ALE pin is used to demultiplex the address and data buses. When the ALE signal is active, the bus lines act as the address bus; when inactive, they function as the data bus, enabling proper communication with external memory.

How does the External Access (EA) pin work with external memory?

The EA pin is used to enable or disable external memory interfacing. It is active when low, indicating that external memory is connected and the microcontroller can communicate with it. When the signal is high, external memory is disabled.