embedded system lect3

Embedded SystemSpring, 2011Lecture 3: The PIC MicrocontrollersEng. Wazen M. Shbair

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Today’s Lecture

Comparison between Microprocessors and Microcontrollers.

Advantages of Microcontroller. Criteria for considering Microcontroller. Overview of the PIC18 Family

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Microprocessor vs. Microcontroller

Microprocessor is general-purpose microprocessors such as Intel’s x86 family.

Microprocessor dose not contain RAM, ROM or I/O Ports on the chip it self.

Microcontroller has CPU and fixed amount of RAM, ROM, I/O Ports and Timer all on a single chip.

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Microprocessor vs. Microcontroller

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Microprocessor vs. Microcontroller

Microprocessor and Microcontroller are widely used in embedded system products.

Typically, in an embedded system the microcontroller’s ROM is burned with a purpose for specific functions needed for the system. (e.x. Printer)

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Choosing a µController

The major 8-bit Freescale Semiconductor’s (formerly Motorola)

68HC08/68HC11 Intel’s 8051 Atmel’s AVR Zilog’s Z8 PIC from Microchip Technology

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Criteria for Choosing µController

1. Meeting the computing needs of the task at hand efficiency and cost effectively

2. Availability of SW and HW development tools Compilers Assemblers Debuggers Emulators

3. Wide availability and reliable source.

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Criteria for Choosing µController

Meeting the computing needs of the task at hand efficiency and cost effectively Determine its type, 8-bit,16-bit or 32-bit Speed Packaging (40-Pin or QFP) Power consumption The amount of RAM and ROM The number of I/O pins and the timer Cost per unit Ease of upgrade.

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µC Data width

8-bit Microcontrollers PIC10, PIC12, PIC14 PIC16, PIC17, PIC18

16-bit Microcontrollers PIC24F, PIC24H

32-bit Microcontrollers PIC32

16-bit Digital Signal Controllers dsPIC30, dsPIC33F

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Overview of the PIC18 Family

An 8-bit µController called PIC is introduces in 1989 by Microchip Technology Corporation

It includes Small Data RAM Few bytes of ROM One timer I/O ports

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PIC 18 Feathers

RISC Architecture On-chip program, Code, ROM Data EEPROM Timers ADC USART I/O Ports

RISC Architecture

Reduced Instruction Set Computer (RISC) Small, highly optimized set of instructions Uses a load-store architecture Short execution time Pipelining Many registers

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Figure 1-2. Simplified View of a PIC Microcontroller

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Microcontroller

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PIC µC program ROM

PIC exists in terms of different speed and the amount of on-chip RAM/ROM

Compatibility is restricted as far as the instructions are concerns.

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PIC µC Program ROM

Its used to store Program or code PIC 18 can support up to 2MB Generally, they come with 4KB – 128KB Available in flash, OTP, UV-EPROM, and

masked.

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UV-EPROM

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PIC18Fxxxx with flash

Its on chip ROM is flash It memory can be erased in second compared

to 20 minute needed for UV-EPROM Used for product development

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PIC18Cxxxx and Masked PIC

One Time Programmable (OTP) C indicates the OTP RPM Used for mass production Cheaper

Masked program will be burned into the PIC chip during

the fabrication process

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PIC C data RAM and EEPROM

Max. 4096 Bytes (4 kB) of data RAM space. Data RAM space has two components

Varied GPR, General Purpose RAM For read/write and data manipulation Divided into banks of 256 B

Fixed SFR, Special Function Registers Some of PICs have a small amount of EEPROM

Used for critical data storing

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PIC µC peripherals

CAN- (Controller Area Network), LIN- (Local Interconnect Network), USB- (Universal Serial Bus), I²C- (Inter-Integrated Circuit), SPI- (Serial Peripheral Interface), Serial or Ethernet Interface ADC - Analog Digital Converter USART- Universal Synchronous Asynchronous

Receiver Transmitter

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References

Jie Hu , ECE692 Embedded Computing Systems , Fall 2010.

PIC Microcontroller And Embedded Systems: using Assembly and C for PIC 18, M. Mazidi, R. McKinlay and D. Causey, Prentice Fall, 2008.

Eng. Husam Alzaq, Embedded System Course, IUG, 2010