Page 67 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

The Micro-controller 8051 can be assembled in such a manner that it momentarily stops or breaks the core
program at the time of the interruption. When the sub-routine task is finished then the implementation of the core
program initiates automatically as usual. There are 5 interrupt supplies in the 8051 Microcontroller, two out of five
are peripheral interrupts, two are timer interrupts and one is serial port interrupt.
Memory
The micro-controller needs a program that is a set of commands. This program enlightens the Microcontroller to
perform precise tasks. These programs need a storage space on which they can be accumulated and interpreted
by the Microcontroller to act upon any specific process. The memory which is brought into play to accumulate the
program of the Microcontroller is recognized as Program memory or code memory. In common language, it’s also
known as Read-Only Memory or ROM.

The microcontroller also needs memory to amass data or operands for the short term. The storage space which is
employed to momentarily data storage for functioning is acknowledged as Data Memory and we employ Random
Access Memory or RAM for this principal reason. Microcontroller 8051 contains code memory or program memory
4K, so which has 4KB Rom and it also comprises data memory (RAM) of 128 bytes.
Bus

Fundamentally Bus is a group of wires which function as a communication canal or means for the transfer of Data.
These buses comprise 8, 16, or more cables. As a result, a bus can bear 8 bits, 16 bits altogether. There are two
types of buses

1 Address Bus: Microcontroller 8051 consists of a 16-bit address bus. It is brought into play to address
memory positions. It is also utilized to transmit the address from the Central Processing Unit to Memory.
2 Data Bus: Microcontroller 8051 comprises of 8 bits data bus. It is employed to cart data.

Oscillator
As we all make out the Microcontroller is a digital circuit piece of equipment, thus it needs a timer for its function.
For this function, Microcontroller 8051 consists of an on-chip oscillator that toils as a time source for the CPU
(Central Processing Unit). As the productivity thumps of the oscillator are steady as a result, it facilitates
harmonized employment of all pieces of the 8051 Microcontroller. Input/Output Port: As we are acquainted with
that Microcontroller is employed in embedded systems to manage the functions of devices.
Thus, to gather it to other machinery, gadgets or peripherals we need I/O (input/output) interfacing ports in Micro-
controller. For this function Micro-controller 8051 consists of 4 input/output ports to unite it to other peripherals.
Timers/Counters
Micro-controller 8051 is incorporated with two 16 bit counters & timers. The counters are separated into 8-bit
registers. The timers are utilized for measuring the intervals, to find out pulse width, etc.

Types of Interrupts
The interrupts of the 8051 microcontrollers have the following sources
TF0 (Timer 0 Overflow Interrupt)
TF1 (Timer 1 Overflow Interrupt)

INT0 (External Hardware Interrupt)
INT1 (External Hardware Interrupt)
RI/TI (Serial Communication Interrupt)
Memory
The memories of the 8051-microcontroller architecture include a program memory and data memory.

The instructions of the CPU are stored in the Program Memory. It is usually implemented as Read-Only Memory
or ROM, where the Program written into it will be retained even when the power is down, or the system is reset.
Data Memory in a Microcontroller is responsible for storing values of variables, temporary data, intermediate
results, and other data for the proper operation of the program.

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CITS : E & H - Electronics Mechanic - Lesson 34 - 42