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Embedded System Spring, 2011 Lecture 3: The PIC Microcontrollers Eng. Wazen M. Shbair. Today’s Lecture. Comparison between Microprocessors and Microcontrollers. Advantages of Microcontroller. Criteria for considering Microcontroller. Overview of the PIC18 Family.
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Embedded SystemSpring, 2011Lecture 3: The PIC MicrocontrollersEng. Wazen M. Shbair
Today’s Lecture • Comparison between Microprocessors and Microcontrollers. • Advantages of Microcontroller. • Criteria for considering Microcontroller. • Overview of the PIC18 Family IUG- Embedded System
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. IUG- Embedded System
Microprocessor vs. Microcontroller IUG- Embedded System
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) IUG- Embedded System
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 IUG- Embedded System
Criteria for Choosing µController • Meeting the computing needs of the task at hand efficiency and cost effectively • Availability of SW and HW development tools • Compilers • Assemblers • Debuggers • Emulators • Wide availability and reliable source. IUG- Embedded System
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. IUG- Embedded System 3-8
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 IUG- Embedded System
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 IUG- Embedded System 3-10
PIC 18 Feathers RISC Architecture On-chip program, Code, ROM Data EEPROM Timers ADC USART I/O Ports IUG- Embedded System
RISC Architecture • Reduced Instruction Set Computer (RISC) • Small, highly optimized set of instructions • Uses a load-store architecture • Short execution time • Pipelining • Many registers
Figure 1-2. Simplified View of a PIC Microcontroller IUG- Embedded System 3-13
Microcontroller IUG- Embedded System 3-15
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. IUG- Embedded System 3-16
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. IUG- Embedded System
UV-EPROM IUG- Embedded System 3-18
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 IUG- Embedded System
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 IUG- Embedded System
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 IUG- Embedded System
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 IUG- Embedded System 3-23
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 IUG- Embedded System