Chp4 introduction to the pic microcontroller copy

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LOGO

Introduction to Introduction to the PIC the PIC

MicrocontrollerMicrocontroller

BEE 3213: Microprocessor & Microcontroller

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LOGO OutlineOutline

What is Microcontroller? µC vs General-Purpose µP A Brief History of PIC µC PIC16F84 Features PIC Clock Generator Reset PORTS Center Processing Unit (CPU) MEMORY ORGANIZATION Timer & Prescalar Flash Memory RAM ROM EEPROM

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LOGO What is Microcontroller?What is Microcontroller?

Integrated chip that contains CPU, RAM, some form of ROM, I/O ports, and timers

Designed for a very specific task to control a particular system

reduce production cost

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LOGO µC µC vs General-Purpose vs General-Purpose µµPP

Microcontroller Microprocessor

Devices Microchip’s PIC’s series, Atmel’s AVR series

Intel’s x86 family (8086, 80286, 80386, 80486 & the Pentium) or (Motorola’s PowerPC family)

Components Internal CPU, RAM, ROM, I/O ports and timers

External RAM, ROM, and I/O ports

Application Perform specific function: A small set of signal processing functions for digital signal processor

Perform more tasks that related to general requirements: calculations of software, personal computer

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LOGO µC µC vs General-Purpose vs General-Purpose µµPP Cont…

CPU / μP

RegisterRegister

Control UnitControl Unit

ALUALU

DATA BUSCPU / μP

Register

Register

Control UnitControl Unit

ALUALU

ADDRESS BUS

CONTROL BUS

μC

RAM ROM I/O TimerSerial COM

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LOGO µC µC vs General-Purpose vs General-Purpose µµPP Cont…

Mic

ropr

oces

sor

EEPROM

RAM

Inputand

outputports

Serial I/O

Parallel I/O

Timer

PWM

Inputand

outputports

A/D

D/A

AnalogI/O

ROM

Mic

ropr

oces

sor

EEPROM

RAM

Inputand

outputports

Serial I/O

Parallel I/O

Timer

PWM

Inputand

outputports

A/DA/D

D/AD/A

AnalogI/O

ROM

Microprocessor-based System Microcontroller-based System

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LOGO A Brief History of PIC µCA Brief History of PIC µC

In 1989, Microchip Technology Corporation introduced an 8-bit µC called PIC (Peripheral Interface Controller).

This 8 pins chip contains a small amounts of data RAM, a few hundred bytes of on-chip ROM for program, one timer, and a few pins for I/O ports.

The family of 8-bit µC: 10xxx, 12xxx, 14xxx, 16xxx, 17xxx, and 18xxx

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LOGO A Brief History of PIC µCA Brief History of PIC µC Cont…

http://www.microchip.com

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They are all 8-bit processors that the CPU can work on only 8 bits of data a time.

Problem: not all 100% upwardly compatible in terms of software when going from one family to another family.

Ex.: 12xxx - 12-bit wide instructions

16xxx- 14-bit wide instructions

PIC18xxx - 16-bit wide with many

new instructions

Cont…

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Advantages of PIC: 30 to 100 times faster than other µCs

(program memory is integrated to the chip) Smaller size (on-board memory) Easy to program, reusable and

inexpensive

Cont…

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Architecture:

Cont…

CPUProgram &

Data MemoryVon Neumann architecture

CPUProgram Memory

Data Memory

Harvard architecture

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LOGO ReviewReview

1.A C normally has which of the following devices on-chip?

(a) RAM (b) ROM (c) I/O (d) all of the above

2.A general-purpose microprocessor normally needs which of the following devices to be attached to it?

(a) RAM (b) ROM (c) I/O (d) all of the above

3. The PIC16 has a(n) ___-bit P.

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LOGO PIC16F84 FeaturesPIC16F84 Features

18 pins, DIP18 type (Dual in Package) or SMD type

Remarks:RA0 - RA3: Pins on port A. No additional functionRA4 : TOCK1 which functions as a timerRB0 : Interrupt input is an additional function.RB1 - RB5: Pins on port B. No additional function.RB6 : 'Clock' line in program mode.RB7 : 'Data' line in program modeMCLR : Reset input and Vpp programming voltageVss : Ground of power supply.Vdd : Positive power supply pole.OSC1 - OSC2 : Pins for connecting with oscillator.

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LOGO PIC16F84 FeaturesPIC16F84 Features Cont…

Block Block diagram of diagram of PIC16F84PIC16F84

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LOGO PIC Clock GeneratorPIC Clock Generator

To provide a clock for executing a program or program instructions of C.

Types of PIC clock generator: A crystal & two capacitors Resonators or external resistor-capacitor pair Built-in resistor-capacitor

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LOGO PIC Clock GeneratorPIC Clock Generator Cont…

PIC16F84 can operate in four different oscillation modes:- LP low power crystal

- XT crystal/resonator

- HS high speed crystal/resonator

- RC resistor/capacitor

Two configuration bits, FOSC1 & FOSC0 are used to select one of these four modes

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Crystal Oscillator/Ceramic Resonators For XT, LP or HS OSC configurations Crystal or ceramic resonator is connected to the

OSC1/CLKIN & OSC2/CLKOUT pins

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A parallel cut crystal is used to design PIC16F84A

The use of a series cut crystal may give a freq. out of the crystal manufacturer’s specifications

External clock input operations

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Capacitor selection for ceramic resonators

Capacitor selection for crystal resonators

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RC Oscillator

Reduce cost for timing insensitive applications Variation of the oscillator frequency:

- operating temperature- process parameter variation- difference in lead frame capacitance between package types (low

CEXT values)- tolerance of the external R & C components

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LOGO ResetReset Power-on Reset (POR) MCLR during normal operation MCLR during SLEEP WDT Reset (during normal

operation) WDT Wake-up (during SLEEP)

Register Reset value (hex)

PC 000000

WREG 00

SP 00

TRISA-TRISB FF

Value registers upon reset

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LOGO ReviewReview

1.Which pin is used to reset the PIC16F84 chip?

2.Upon power-up, the program counter (PC) has a value of ____.

3.Upon power-up, the PIC16F84 fetches the first opcode from ROM address location _____.

4.MCLR is an active-_____ (LOW, HIGH) pin.

5.How many Vdd and Gnd pins are in the PIC16F84 chip?

6. In the PIC16, the program counter is ____ bits wide.

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LOGO PORTSPORTS

Physical connection of CPU and outside world – monitor @ control other components @ devices

A group of pins which can be accessed simultaneously @ set the desired combination of zeros and ones

All port pins can be designated as input @ output

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LOGO PORTS: PORTS: PORTA & TRISAPORTA & TRISA

PORTA is a 5-bit wide, bi-directional port TRISA: data direction register of PORTA

TRISA = 1, PORTA is an input (output driver in HI-impedance mode)

TRISA = 0, PORTA is an output (contents of the output latch on the selected pin)

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LOGO PORTS: PORTS: PORTB & TRISBPORTB & TRISB

PORTB is a 8-bit wide, bi-directional port TRISB: data direction register of PORTB

TRISB = 1, PORTB is an input (output driver in HI-impedance mode)

TRISB = 0, PORTB is an output (contents of the output latch on the selected pin)

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LOGO ReviewReview

1.There are total of ____ ports in the PIC16F84.

2.True or false. All of the PIC16F84 ports have 8 pins.

3.List the PIC16F84 port that has 8 pins.

4.True or false. Upon power-up, the I/O pins are configured as output ports.

5.To make Port B an output port, we must place ____ in register _____.

6.To make Port B an input port, we must place ____ in register _____.

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LOGO Center Processing Unit (CPU)Center Processing Unit (CPU)

The brain of the C Connect all parts of the C through a data bus

& and an address bus Find, fetch, decode & execute the right

instruction CPU resources:

Registers: store temporary information ALU: performing arithmetic functions Program counter: point to the address of the next

instruction to be executed Instruction decoder: interpret the instruction

fetched into the CPU

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LOGO Center Processing Unit (CPU)Center Processing Unit (CPU)

MOVLW 0x20

Program Memory

Temporary storage

executeexecute

Memory11 00xx 0010 0000

opcode

Assembler (translator)

Decoder

Fetch instruction

Fetch instruction

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LOGO Center Processing Unit (CPU)Center Processing Unit (CPU)Cont…

Arithmetic Logic Unit (ALU) Add, subtract, move (left @ right within a register) and

logic operations PIC16F84 contains an 8-bit ALU & 8-bit working

registers (WREG) ALU instructions: two operands @ one operand Two operands: WREG + file register @ immediate

constant Registers: GPR (General Purposes Registers) & SFP

(Special Function Registers) One operand: WREG @ a file register Execution of ALU instructions can affect STATUS bits

which are carry (C), digit carry (DC), and zero (Z).

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LOGO Center Processing Unit (CPU)Center Processing Unit (CPU)Cont…

ALUSTATUS register

8-bit literal (from instruction word)

WREG register

8-bit

8-bit

8-bit

Z, DC, C flags

Carry bit

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LOGO MEMORY ORGANIZATIONMEMORY ORGANIZATION

PIC16F84 has two separate memory blocks: data & program

Data block: GPR and SFP registers in RAM memory (read/write memory- static memory), EEPROM memory

Program block: FLASH memory

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LOGO

Memory organization of PIC16F84

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LOGO MEMORY ORGANIZATION:MEMORY ORGANIZATION: Program MemoryProgram Memory

Used for storing programs (opcodes), directly under control of program counter (PC)

Wake up memory (address 0000H) when PIC is powered up.

Has been carried out in FLASH technology (indicated by the letter F in the part number, C for one-time programmable (OTP)): possible to program a C many times

Size of 1024 locations, 14 bits width Locations 0000h & 0004h are reserved for reset &

interrupt vector, respectively The 1st 1Kx14 (0000h-03FFh) are physically

implemented address Accessing a location of physically implemented address

will cause a wraparound

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LOGO MEMORY ORGANIZATION:MEMORY ORGANIZATION: Program MemoryProgram Memory

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LOGO MEMORY ORGANIZATION:MEMORY ORGANIZATION: Data MemoryData Memory

Also known as file register: data storage, scratch pad & registers for internal use and functions

Special Function Registers (SFR)- 8-bit wide - ALU status, timers, serial communication, I/O ports, ADC, & etc.- function of each SFR is fixed in design, used to control C or peripheral- access either directly (names @ addresses) or indirectly (FSR – File Select

Register)- classified into core and peripheral sets- control bits (RP1, RP0) in STATUS register are used for bank selection

General Purpose Registers (GPR)- 8-bit wide- also called general purpose RAM (GP RAM)- used for data storage & scratch pad- accessed directly- addresses in Bank 0 & Bank 1 are mapped together

Location of SFR and GPR vary from chip to chip, even among members of the same family

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LOGO

Data Memory Organization

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SFR File Memory

Legend: x = unknown, u = unchanged, - = unimplemented, read as '0', q = value depends on conditionNote 1: The upper byte of the program counter is not directly accessible. PCLATH is a slave register for PC<12:8>. The contents of PCLATH can be

transferred to the upper byte of the program counter, but the contents of PC<12:8> are never transferred to PCLATH.2: The TO and PD status bits in the STATUS register are not affected by a MCLR Reset.3: Other (non power-up) RESETS include: external RESET through MCLR and the Watchdog Timer Reset.4: On any device RESET, these pins are configured as inputs.5: This is the value that will be in the port output latch.

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LOGO ReviewReview

1.True or false. Every member of the PIC16 family, regardless of the program ROM size, wakes up at memory 0000H when it is powered up.

2.What is the main difference between the PIC16Fxxx and PIC16Cxxx C?

3.The GPR and SFR together are called ____.

4.The SFR registers in PIC are ___-bit.

5.The data memory in PIC16 is divided into ____-byte banks.

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LOGO Timer & PrescalarTimer & Prescalar

Establish relation between a real dimension such as “time” and a variable which represents status of a time within a microcontroller

PIC16F84 has an 8-bit timer, whose its value is continually increasing to 255 and then it starts all over again: 0, 1, 2, 3, …, 255, 0, 1,… etc

Prescaler divides oscillator clock before it reaches logic that increases timer status.

The first three bits in OPTION register defines divisor 256 is the highest divisor, means timer clock would

increase by one at every 256th clock

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LOGO Timer & PrescalarTimer & Prescalar Cont…

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LOGO Flash MemoryFlash Memory

Store permanent information on some palm-sized computers (operating system & core applications)

Unlike RAM (random-access memory), flash memory can continue to store information in the absence of a power source.

Unlike ROM (read-only memory), we can write/update to flash memory

More expensive than ROM

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LOGO RAMRAM

Random-access memory The most common computer memory to

perform necessary tasks while the computer is on

An integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible.

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LOGO ROMROM

Read Only Memory Non-volatile: hold programs and data that must

be retained even the computer is turned off data cannot be easily written to ROM; depending

on the technology used in the ROM, writing may require special hardware, or may be impossible.

A computer's BIOS may be stored in ROM.

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LOGO EEPROMEEPROM

Electrically Erasable Programmable Read Only Memory

ROM that can be erased electronically and reprogrammed in-circuit (or with a device programmer).

EEPROM is very similar to flash memory. The biggest difference is that the bytes (words) of an EEPROM can be erased individually.

Chp4 introduction to the pic microcontroller copy

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