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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LOGO A Brief History of PIC µCA 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…
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LOGO A Brief History of PIC µCA 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…
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LOGO A Brief History of PIC µCA Brief History of PIC µC
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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LOGO PIC Clock GeneratorPIC Clock Generator Cont…
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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LOGO PIC Clock GeneratorPIC Clock Generator Cont…
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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LOGO PIC Clock GeneratorPIC Clock Generator Cont…
Capacitor selection for ceramic resonators
Capacitor selection for crystal resonators
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LOGO PIC Clock GeneratorPIC Clock Generator Cont…
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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LOGO
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.