AT89S52 MICROCONTROLLER

Microcontroller is a microprocessor designed specifically for control applications, and is equipped with ROM, RAM and facilities I / O on a single chip.AT89S52 is one of the family MCS-51/52 equipped with an internal 8 Kbyte Flash EPROM (Erasable and Programmable Read Only Memory), which allows memory to be reprogrammed.

Designed by Atmel AT89S52 in accordance with standard instructions and pin layout 80C5.

AT89S52 Microcontroller Features :

• A CPU (Central Processing Unit) 8 Bit.
• 256 bytes of RAM (Random Access Memory) internally.
• Four-port I / O, which each consist of eight bits
• the internal oscillator and timing circuits.
• Two timer / counters 16 bits
• Five interrupt lines (two fruits and three external interrupt internal interruptions).
• A serial port with full duplex UART (Universal Asynchronous Receiver Transmitter).
• Able to conduct the process of multiplication, division, and Boolean.
• the size of 8 KByte EPROM for program memory.
• Maximum speed execution of instructions per cycle is 0.5 s at 24 MHz clock frequency.
If the microcontroller clock frequency used is 12 MHz, the speed is 1 s instruction execution

CPU (Central Processing Unit)
This section serves to control the entire operation on the microcontroller.This unit is divided into two parts, the control unit, or CU (Control Unit) and the arithmetic and logic unit or ALU (Aritmetic Logic Unit) The main function control unit is to take instructions from memory (fetch) and then translate the composition of these instructions into a simple collection of work processes (decode), and implement instruction sequence in accordance with the steps that have been determined the program (execute). Arithmetic and logic unit is the part that deals with arithmetic operations like addition, subtraction, and logical data manipulation operations such as AND, OR, and comparison.

Part Input / Output (I / O)
This section serves as a communication tool with a single chip device outside the system. Consistent with the name, I / O devices can receive and provide data to / from a single chip.

There are two kinds of devices I / O is used, ie devices for serial connection UART (Universal Asynchronous Receiver Transmitter) and device for so-called parallel relationship with the PIO (Parallel Input Output).Both types of I / O has been available in a single chip AT89S52.

Software
Single flakes MCS-51 family has a special programming language that is not understood by other types of single flakes. This programming language known by the name of the assembler language instruction has 256 devices.However, when this can be done with microcontroller programming using C language.With the C language, microcontroller programming easier, because the C language format will be automatically converted into assembler language with a hex file format.Software on a microcontroller can be divided into five groups as follows:

Data Transfer Instructions
This instruction serves to move the data, between registers, from memory to memory, from registers to memory, and others.

Arithmetic Instruction
These instructions perform arithmetic operations including addition, subtraction, addition of one (increments), a reduction of one (decrement), multiplication and division.

Logic and Bit Manipulation Instructions
Functions perform logic operations AND, OR, XOR, comparison, shift and complement data.

Branching instructions
Serves to alter the normal sequence of execution of a program. With this instruction, the programs that are implemented will jump to a particular address.

Instruction Stack, I / O and Control
These instructions set the stack usage, read / write I / O ports, and controlling.

Pin Configuration
AT89S52 microcontroller has 40 pins with a single 5 Volt power supply. The pin 40 is illustrated as follows:

AT89S52 MICROCONTROLLER configuration

The function of each pin AT89S52 is:
Pin 1 to 8 (Port 1) is an 8-bit parallel port of a two-way (bidirectional) that can be used for different purposes (general purpose).
Pin 9 is a pin reset, reset is active if a high ration.

• P3.0 (10): RXD (serial port data receiver)
• P3.1 (11): TXD (serial port data sender)
• P3.2 (12): INT0 (external interrupt 0 input, active low)
• P3.3 (13): INT1 (ekstrernal an interrupt input, active low)
• P3.4 (14): T0 (external input timer / counter 0)
• P3.5 (15): T1 (external input timer / counter 1)
• P3.6 (16): WR (Write, active low) control signal from port 0 write data to memory and input-output data externally.
• P3.7 (17): RD (Read, active low) control signal of the reading of input-output data memory external to the port 0. XTAL pin 18 as the second, the output is connected to the crystal oscillator. XTAL pin 19 as the first, high berpenguatan input to the oscillator, connected to the crystal.

Pin 20 as Vss, is connected to 0 or ground on the circuit.

Pin 21 to 28 (Port 2) is 8 bits parallel ports in both directions. This port sends the address byte when accessing external memory is carried on.
Pin 29 as the PSEN (Program Store Enable) is the signal used for reading, move the program the external memory (ROM / EPROM) to microcontroller (active low).
Pin 30 as the ALE (Address Latch Enable) to hold down the address for accessing external memory. This pin also functions as a prog (active low) that is activated when the internal program flash memory on the microcontroller (on chip).

Pin 31 as the EA (External Accesss) to select the memory to be used, the internal program memory (EA = Fcc) or external program memory (EA = Vss), also serves as Vpp (programming supply voltage) when programming the internal flash memory on the microcontroller Pin 32 to 39 (Port 0) is an 8-bit parallel port in both directions. Under which functions as a multiplexed address data to access an external program and data memory.Pin 40 as Fcc, connected to +5 V as a ration to the microcontroller.All single chip in the family division of MCS-51 has the address space to programs and data. The separation of program memory and data memory allows data to be accessed by a memory address 8 bits.Even so, the address memory 16 bits of data can be generated through the DPTR register (Point Data Register). Program memory can only be read can not be written because it is stored in the EPROM.In this case the EPROM is available in a single chip AT89S52 for 8 Kbyte

AT89S52 MICROCONTROLLER memory

Memory Program

If EA’s low value, the program will occupy the address 1000 H to FFFF H to external programs.

Data memory

Internal data memory are mapped as shown below memory space is divided into three blocks of the 128 down, 128 up, and space SFR (Special Function Register) Under Section 128 bytes of RAM mapped into the 32 bytes are grouped into four banks and eight registers (R0 to R7). In the next 16 bytes, on the banks of register, form a block of memory space that can teralamati per bit (bit addressable).All bytes that are within 128 below can be accessed either directly or indirectly.Section 128 above can only be accessed by indirect addressing. Section 128 of the RAM is solely in the devices have 256 bytes of RAM.

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