Pic Introduction.pdf

PIC MICROCONTROLLERS

Peeyush.K.P. Amrita School of Engineering Coimbatore

What is an Embedded System? Communication

Avionics Automobile

Consumer Electronics

Office Equipments Household Appliances 2

What is an Embedded system? System in which software is embedded into the hardware ( firmware). The core part of the system will be a programmable device.

Automotive Embedded Systems 

Today’s high-end automobile have > 80 microprocessors:    

4-bit microcontroller checks seat belt; microcontrollers run dashboard devices; 16/32-bit microprocessor controls engine. Millions lines of code

4

Vending Machines

5

Sojourner

6

GPS Receivers

7

Why Embedded systems?       

Reduced number of components. Reduced size. Reduced cost. Reduced power consumption. Easier upgradation. Easier troubleshooting & maintenance. Best suited for specific controlling applications.

Why uC? 

Microprocessor: •

Requires ‘external’ support hardware •

•



E.g., External RAM, ROM, Peripherals.

Application:Processing-Arithmetic,logic operations.

Microcontroller: • • •

Very little external support hardware/Stand alone. Most RAM, ROM and peripherals on chip. “Computer on a chip”, or “System on chip” (SOC) •

•

E.g., PIC = Peripheral Interface Controller

Application: Controlling purposes.

Microcontroller

VARIOUS MICROCONTROLLERS 

8 bit microcontrollers    



16 bit microcontrollers 



Microchip - PIC 18 series

32 bit microcontrollers 



Microchip - PIC 12 & 16 Series. Atmel - 89c51 Intel - 8051 Motorola - 68HCxx series

ARM Processors

DSP based microcontrollers 

Shark

Two Different Architectures

RISC vs. CISC 

Reduced Instruction Set Computer (RISC) 







Used in: SPARC, ALPHA, Atmel AVR, etc. Few instructions (usually < 50) Only a few addressing modes Executes 1 instruction in 1 internal clock cycle (Tcyc)



Complex Instruction Set Computer (CISC) 



 

Used in: 80X86, 8051, 68HC11, etc. Many instructions (usually > 100) Several addressing modes Usually takes more than 1 internal clock cycle (Tcyc) to execute

WHY PIC ?

WHY PIC ?



PICs use the Harvard Architecture PICs and most Harvard chips are “RISC” 35 Instructions



Executes 1 instruction in 1 internal clock cycle

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In-Circuit Serial Programmable (ICSP) – via two pins. Available in different packages

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Features     

Power On Reset Timer Oscillator Startup Timer WatchDog Timer Sink/Source Current – 25ma Flash Programming

POR/Oscillator Startup Timer

WatchDog Timer 00 01 02 .. .. FF Roll Over 00

Sink/Source Current – 25ma

The PIC Family: Cores PICs come with 1 of 3 CPU ‘cores’: The Base-line : 12bit cores with 33 instructions. Eg:12C50x, 12C67x

The Mid-Range : 14bit cores with 35 instructions. Eg:16C5x,16Cxxx

The High-End : 16bit cores with 58 instructions. Eg:17C4x,17C7xx ‘Enhanced’ 16bit cores with 77 instructions: 18Cxxx

Areas of Application. 

Base-line  



Mid-range  



Inexpensive controllers, glue logic, simple tasks. E.g., quadrature decoding, digital interfacing. Multitasking programs, serial communication. E.g., Cheap data acquisition system and digital I/O system for PC off COM ports, data logging.

High-end 



RTOS, low end DSP, communications, big moosey applications. E.g., FEC converter, Rocket Flight Computer, cheap FFT chip.

Program Memory (ROM)-size PIC program space is different for each chip. Some examples are: 12C508 16C71C 16F877 17C766

512 12bit instructions 1024 (1k) 14bit instructions 8192 (8k) 14bit instructions 16384 (16k) 16bit instructions

Program Memory (ROM)-types PICs have two different types of program storage: EPROM (Erasable Programmable Read Only Memory) Needs high voltage from a programmer to program (~13V) Needs windowed chips and UV light to erase Note: One Time Programmable (OTP) chips are EPROM chips, but with no glass window. ( ‘CR’ ) PIC Examples: Any ‘C’ part: 12C50x, 17C7xx, etc.

Program Memory (ROM)-types. FLASH Re-writable (even by chip itself) Much faster to develop on! Finite number of writes (~100k Writes) PIC Examples: Any ‘F’ part: 16F84, 16F87x, 18Fxxx (future)

Data Memory (RAM-volatile) PICs use general purpose “file registers” for RAM (each register is 8bits for all PICs)

Some examples are: 12C508 16C71C 16F877 17C766

25 Bytes RAM 36 Bytes RAM 368 Bytes 902 Bytes RAM

Data Memory (EEPROM non-volatile)

  

For permanent storage of data. Available in few PICs only. Eg:16F8X,12CE5XX,16F87X

Speed PICs require a clock to work. Can use crystals, clock oscillators, or even an RC circuit. Some PICs have a built in 4MHz RC clock - Not very accurate, but requires no external components! Instruction speed = 1/4 clock speed (Tcyc = 4 * Tclk) All PICs can be run from DC to their maximum spec’d speed: 12C50x 12C67x 16Cxxx 17C4x /17C7xxx 18Cxxx

4MHz 10MHz 20MHz 33MHz 40MHz

Peripherals Different PICs have different on-board peripherals Some common peripherals are:  Tri-state (“floatable”) digital I/O pins.  Analog to Digital Converters (ADC) (8, 10 and 12bit, 50ksps). 2  Serial communications: UART (RS-232C), SPI, I C, CAN.  Pulse Width Modulation (PWM) (10bit).  Timers and counters (8 and 16bit).  Watchdog timers, Brown out detect, LCD drivers.

Packages PICs come in a huge variety of packages: 8 pin DIPs, SOICs: 18pin DIPs, SOICs: 28pin DIPs, SOICs: 40pin DIPs, SOICs: 44 - 68pin PLCCs*:

12C50x (12bit) , 12C67x (14bit) 16C5X (12bit), 16Cxxx (14bit) 16C5X (12bit), 16Cxxx (14bit) 16Cxxx (14bit), 17C4x (16bit) 16Cxxx (14bit), 17Cxx (16bit)

Commonly used mid range series PICs   

The 16F8x series- 16F84. The 16F7x series- 16F73,74,76,77. The 16F87x series- 16F873, 874,876,877.

Comparison of Commonly Used Mid range series of PIC 16f8X

7X

87X

10MHz 400ns 2 Yes

20MHz 200ns 8 No

20MHz 200ns 8 Yes

8bit X 1

8bit X 2 + 16bit X 1

8bit X 2 + 16bit X 1

No No No No No

2 8bit 1 1 Yes

2 10bit 1 1 Yes

Operating Speed Clock input Instruction cycle

Stack levels Data EEPROM Timers CCP modules ADC USART/SCI SSP/SPI/I2C Interrupt on Pin Change

Comparison of Commonly Used Mid range series of PIC 83

84

73/873

74/874

76/876

77/877

Total pins

18

18

28

40

28

40

I/O Ports

A,B

A,B

A,B,C

A,B,C,D,E

A,B,C

A,B,C,D,E

I/O Pins

13

13

22

33

22

33

Prog. m/y

512 B

1 KB

4 KB

4 KB

8 KB

8 KB

Data m/y

36 B

68 B

192 B

192 B

368 B

368 B

EEPROM

64

64

128

128

256

256

PSP

No

No

No

Yes

No

Yes

ADC channels

NA

NA

5

8

5

8

BOR

No

No

Yes

Yes

Yes

Yes

PIC 16F874/877

PIC 16F874/877

PIN DIAGRAM

PIC16F877A Block Diagram Instruction Memory

Data Memory

Instruction Bus

Data Bus Must be involved in all arithmetic operations Most important register in the PIC

PIC16F877A Memory 

The PIC16F877A has an 8192 (8k) 14bit instruction program memory



368 Bytes Registers as Data Memory :  Special Function Registers: used to control peripherals and PIC behaviors  General Purpose Registers: used to a normal temporary storage space (RAM)



256 Bytes of nonvolatile EEPROM

PIC16F877A Memory Map

SFR

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INSTRUCTION SET 1) Move Literal Value To Work Register Syntax : MOVLW Eg: MOVLW

0X02

2) Move Content of Work Reg. To File Reg. Syntax : MOVWF Eg : MOVWF

PORTA

3) Move Content of File Reg. To Desti. Syntax : MOVF Eg : MOVF Eg : MOVF

, PORTA,0 PORTA,1

INSTRUCTION SET 1) Bit Set File Register Syntax : BSF Eg: BSF

, PORTA,1

2) Bit Clear File Register Syntax : BCF Eg : BCF

, PORTA,1

INSTRUCTION SET 1) Bit Test File Register Skip if Set Syntax : BTFSS Eg: BTFSS

, PORTA,1

2) Bit Test File Register Skip if Clear Syntax : BTFSC Eg : BTFSC

, PORTA,1

INSTRUCTION SET 1) Decrement File Register Skip if Zero Syntax : DECFSZ Eg: DECFSZ

, COUNT,1

2) Increment File Register Skip if Zero Syntax : INCFSZ Eg : INCFSZ

, COUNT,1

Programming PIC

Basic Circuit

Thank You For Your Kind Attention……