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Chp4 introduction to the pic microcontroller   copy
 

Chp4 introduction to the pic microcontroller copy

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    Chp4 introduction to the pic microcontroller   copy Chp4 introduction to the pic microcontroller copy Presentation Transcript

    • Introduction to the PIC Microcontroller BEE 3213: Microprocessor & Microcontroller
    • Outline
      • What is Microcontroller?
      • µC vs General-Purpose µ P
      • 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
    • 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
    • µC vs General-Purpose µ P 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
    • µC vs General-Purpose µ P Cont… CPU / μ P Register Control Unit ALU DATA BUS CPU / μ P Register Control Unit ALU ADDRESS BUS CONTROL BUS μ C RAM ROM I/O Timer Serial COM
    • µC vs General-Purpose µ P Cont… Microprocessor-based System Microcontroller-based System
    • A 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
    • A Brief History of PIC µC Cont… http://www.microchip.com
    • A Brief History of PIC µC
      • 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…
    • A Brief History of PIC µC
      • 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…
    • A Brief History of PIC µC
      • Architecture:
      Cont… CPU Program & Data Memory Von Neumann architecture CPU Program Memory Data Memory Harvard architecture
    • Review
      • A  C normally has which of the following devices on-chip?
      • (a) RAM (b) ROM (c) I/O (d) all of the above
      • 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.
    • PIC16F84 Features
      • 18 pins, DIP18 type (Dual in Package) or SMD type
      Remarks: RA0 - RA3 : Pins on port A. No additional function RA4 : TOCK1 which functions as a timer RB0 : 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 mode MCLR : Reset input and Vpp programming voltage Vss : Ground of power supply. Vdd : Positive power supply pole. OSC1 - OSC2 : Pins for connecting with oscillator.
    • PIC16F84 Features Cont… Block diagram of PIC16F84
    • PIC 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
    • PIC Clock Generator
      • 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
      Cont…
    • PIC Clock Generator
      • Crystal Oscillator/Ceramic Resonators
      • For XT, LP or HS OSC configurations
      • Crystal or ceramic resonator is connected to the OSC1/CLKIN & OSC2/CLKOUT pins
      Cont…
    • PIC Clock Generator
      • 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
      Cont… External clock input operations
    • PIC Clock Generator Cont… Capacitor selection for ceramic resonators Capacitor selection for crystal resonators
    • PIC Clock Generator
      • 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
      Cont…
    • Reset
      • Power-on Reset (POR)
      • MCLR during normal operation
      • MCLR during SLEEP
      • WDT Reset (during normal operation)
      • WDT Wake-up (during SLEEP)
      Value registers upon reset Register Reset value (hex) PC 000000 WREG 00 SP 00 TRISA-TRISB FF
    • Review
      • Which pin is used to reset the PIC16F84 chip?
      • Upon power-up, the program counter (PC) has a value of ____.
      • Upon power-up, the PIC16F84 fetches the first opcode from ROM address location _____.
      • MCLR is an active-_____ (LOW, HIGH) pin.
      • How many Vdd and Gnd pins are in the PIC16F84 chip?
      • In the PIC16, the program counter is ____ bits wide.
    • PORTS
      • 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
    • PORTS: PORTA & 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)
    • PORTS: PORTB & 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)
    • Review
      • There are total of ____ ports in the PIC16F84.
      • True or false. All of the PIC16F84 ports have 8 pins.
      • List the PIC16F84 port that has 8 pins.
      • True or false. Upon power-up, the I/O pins are configured as output ports.
      • To make Port B an output port, we must place ____ in register _____.
      • To make Port B an input port, we must place ____ in register _____.
    • 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
    • Center Processing Unit (CPU) execute Memory Assembler (translator) Decoder MOVLW 0x20 Program Memory Temporary storage 11 00xx 0010 0000 opcode Fetch instruction Fetch instruction
    • Center Processing Unit (CPU)
      • 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).
      Cont…
    • Center Processing Unit (CPU) Cont… ALU STATUS register 8-bit literal (from instruction word) WREG register 8-bit 8-bit 8-bit Z, DC, C flags Carry bit
    • MEMORY 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
    • Memory organization of PIC16F84
    • MEMORY ORGANIZATION: Program 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 1 st 1Kx14 (0000h-03FFh) are physically implemented address
      • Accessing a location of physically implemented address will cause a wraparound
    • MEMORY ORGANIZATION: Program Memory
    • MEMORY ORGANIZATION: Data 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
    • Data Memory Organization
    • SFR File Memory Legend: x = unknown, u = unchanged, - = unimplemented, read as '0', q = value depends on condition Note 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.
    • Review
      • 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.
      • What is the main difference between the PIC16Fxxx and PIC16Cxxx  C?
      • The GPR and SFR together are called ____.
      • The SFR registers in PIC are ___-bit.
      • The data memory in PIC16 is divided into ____-byte banks.
    • Timer & 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 256 th clock
    • Timer & Prescalar Cont…
    • Flash 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
    • RAM
      • 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.
    • ROM
      • 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.
    • EEPROM
      • 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.