PIC-18 MICROCONTROLLER

Under the Guidence of Mr. ROHITH.S

PRESENTED BY:-

1. ASHISH RANJAN (9008149020)

What is Microcontroller ?

Microcontroller

8051 PIC ARM

TYPES OF MICROCONTROLLER

Features of PIC-18 Microcontroller

It is 8-bit Microcontroller.

It has 16-bit Instruction sets.

256 byte of EPROM.

2 KB SRAM.

32 KB Flash Memory.

It Operates at 40 MHz Crystal Oscillator.

It has 10-bit A/D Converter.

It supports Instruction Pipelining.

It is implemented with nano watt Technology

(low power consumption ).

PIN DIAGRAM OF PIC-18 MICROCONTROLLER

ARCHITECTURE OF PIC-18 MICROCONTROLLER

PIC-18 ADDRESSING MODES

Register Direct : Use an 8-bit value to specify a data register.

Ex:- movwf 0x20,A ; the value 0x20 is register direct mode

Immediate Mode : A value in the instruction to be used as an operand.

Ex:- addlw 0x10 ; add hex value 0x10 to WREG

movlw 0x30 ; load 0x30 into WREG

Inherent Mode : an implied operand.

Ex:- andlw 0x3C ; the operand WREG is implied

daw ; the operand WREG is implied

Indirect Mode : A special function register (FSRx) is used as a pointer to

the actual data register.

Ex:- movwf INDFx (where x = 0,1,2,3)

PIC-18 MEMORY ORGANIZATION

Data Memory and Program Memory are separated.

Separation of Data memory and Program memory makes possible the

the simultaneous access of data and instruction.

Data memory are used as general purpose registers or special function

registers.

On-chip Data EPROM are provided in some PIC-18 MCUs

Separation of Data Memory and Program Memory

Program

Memory

Space

PIC-18

CPU

21-bit program

address

16-bit

instruction bus

Data

Memory

Space

12-bit Register

address

8-bit Data Bus

Fig:- The PIC-18 Memory Spaces

PIC-18 DATA MEMORY

It consist of General purpose register and Special function registers.

Both are referred to as Data Registers.

PIC-18 has 4KB Data Memory.

Data Memory is Divided into Banks and each Bank has 256 bytes.

General purpose registers are used to hold dynamic data.

Special function register are used to control the Operation of Peripheral functions.

Only on bank is active at any time.

It implement access bank to reduce problem caused by bank switching.

Access bank Consists of the lowest 96 bytes and the highest 160 bytes of the data

memory space.

Fig : Data Memory map for PIC-18 Device

PROGRAM MEMORY ORGANIZATION

The program counter (PC) is 21-bit long, which enables the user program to

access up to 2MB program memory.

After Power On it starts to execute the instruction from address 0.

The Location 0x08 is reserved for high-priority interrupt service routine.

The Location 0x18 is reserved for low-priority interrupt service routine.

Up to 128 KB of Program Memory is inside the MCU chip.

Rest Part of the program memory is located outside of the MCU chip.

Fig: Program Memory Organization for PIC-18 Device

PIC-18 PIPELINING The PIC18 Divide most of the instruction execution into two

stages: instruction fetch and instruction execution.

Up to two instructions are overlapped in their execution. One instruction

is inexecution fetch stage while the second instruction is in execution stage.

Because of pipelining, each instruction appears to take one instruction

cycle to complete.

Fetch 2

Execute 1

Fetch 4

Fetch 3

Fetch 1

Execute 2

Execute 3

Execute sub_1Fetch sub_1

Flush

TCY0 TCY1 TCY2 TCY3 TCY4 TCY5

Fig : An Example of Instruction Pipeline flow

THANK YOU…..