Monday, November 23, 2009

Features of PIC Microcontroller

PIC microcontrollers are amazingly powerful fully featured processor with internal RAM, EEROM FLASH memory and peripherals. One of the smallest ones occupies the space of a 555 timer but has a 10bit ADC, 1k of memory, 2 timers, high current I/O ports a comparator a watch-dog timer.

PIC microcontrollers are available depending upon specifications:

Memory Type

  • Flash
  • OTP (One-time-programmable)
  • ROM (Read-only-memory)
  • ROMless

I/O Pin Count

  • 4–18 pins
  • 20–28 pins
  • 32–44 pins
  • 45 and above pins

Memory Size

  • 0.5–1K
  • 2–4K
  • 8–16K
  • 24–32K
  • 48–64K
  • 96–128K

Special Features

  • CAN
  • USB
  • LCD
  • Motor Control
  • Radio Frequency

Although there are many models of PIC microcontrollers, the nice thing is that they are upward compatible with each other. A program developed for one model can very easily, and in many cases without modifications, can be run on other models of the family.

The basic assembler instruction set of PIC microcontrollers consists of only 33 instructions and most of the family members (except the newly developed devices) use the same instruction set. This is why a program developed for one model can run on another model with similar architecture without any changes.

Basic features of PIC microcontrollers:

Harvard RISC instruction set
Digital I/O ports
On-chip timer with 8-bit prescaler
Power-on reset
Watchdog timer
Power saving SLEEP mode
High source and sink current
Direct, indirect, and relative addressing modes
External clock interface
RAM data memory
EPROM or Flash program memory

Additional features:

Advanced Timer
External and Internal interrupts
Internal Oscillator

Advanced features:

CAN bus interface
I2C bus interface
SPI bus interface
Direct LCD interface
USB interface
Motor control

Selection of PIC Microcontroller

There are many PIC models, which can fulfill your Embedded System requirements. While selecting the PIC or any microcontroller for Embedded System, the microcontroller should satisfies the minimum requirements and the does not offer more than the system requirement.

Few factors to be consider while selecting a Microcontroller for Embedded System Design:

Number of I/O pins required
Required peripherals (e.g. USART, USB)
The minimum size of program memory
The minimum size of RAM
Whether or not EEPROM non-volatile data memory is required
Physical size

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