10-05-2012, 12:46 PM
PIC MICROCONTROLLER
PIC MICROCONTROLLER.doc (Size: 52.5 KB / Downloads: 31)
The core of your project is PIC (Peripheral Interface Controller) MICROCONTROLLER. Here we are using a PIC16F877A.It is a general purpose 8 bit microprocessor which offers high performance and very low power consumption. The embedded information processing revolution is truly hidden inside the product we use every day. Micro controllers drive the revolution in embedded intelligence.
The micro controller is the most important part of weather station. The micro controller contains CPU, I/Ports, RAM, ROM, timers; COM ports all in single a chip. This reduces the power consumption and space. The PIC, which means Peripheral Interface Controller, is an 8-bit micro controller from Microchip Technology. Here PIC 16F877 series is used which meet the task efficiently.
The PIC stands for Peripheral Interface Controller as coined by MICROCHIP TECHNOLOGY INC USA, to identify its single chip micro controllers. They are directed at the 8 bit micro controllers, the largest segment of micro controllers.
It is popularly used for embedded control solutions with more than 20,000 design wins to credit. In our project we have used PIC16F877 micro controller, which is based on CMOS technology. We have used a microcontroller instead of microprocessor because the former requires external hardware like external RAM, ROM; external peripherals etc. a microprocessor with all the external hardware can be called a microcontroller. Some of the features of microprocessors are
• Used in: 80X86 (PCs), 8051, 68HC11, etc.
• Only one bus between CPU and memory.
RAM and program memory share the same bus same memory, and so must have same bit width.
• Bottle neck: getting instructions interferes with accessing RAM.
• Complex Instruction Set Computer (CISC).
• Many instructions (usually > 100).
• Many addressing modes.
• Usually takes more than one internal clock cycle.
Microcontroller core features
• High Performance RISC CPU.
• Only 35 single word instructions to learn.
• All single cycle instructions except for program branches, which are two cycles.
• Operating speed: DC-20MHZ clock input.
• DC-200ns instruction cycle.
• Up to 8K*14 words of FLASH Program memory.
• Up to 368*8 bytes of Data Memory (RAM).
• Up to 256*8 bytes of EEPROM data memory.
• Pin out compatible to other 40 pin PIC 16F877 micro controller.
• Interrupt capability (up to 14 sources).
• Eight level deep hardware stack.
• Direct, indirect and relative addressing modes.
• Power-on Reset(POR)
• Power-up Timer(PWRT) and Oscillator Start-up Timer(OST)
• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation.
• Programmable code-protection
• Power saving SLEEP mode
• Selectable oscillator options
• Low-power, high-speed CMOS FLASH/EEPROM technology
• Fully static design
• In-Circuit Serial Programming (ICSP) via two pins.
• Single 5V ICSP capability
• In-circuit Debugging via two pins
• Processor read/write access to program memory.
• Wide operating voltage range: 2.0 to 5.5V.
• High Sink/Source Current: 25mA
• Commercial and Industrial temperature ranges.
• Low – power consumption.
• -<2mA typical @ 5V, 4MHz
• -<20 A typical @ 3V, 32 kHz
• -<1micro ampere typical stand by current.
Peripheral features
• Timer0: 8-bit timer/counter with 8-bit prescaler.
• Timer1: 16-bit timer/counter with prescaler, can be incremented during
Sleep via external crystal/clock.
• Timer2: 8-bit timer/counter with 8-bit register, prescaler and post scaler
• Two Capture/Compare/PWM modules.
• Capture is 16-bit, max.resolution is 12.5ns, Compare is 16-bit, and max.resolution is 200ns.
• PWM max.resolution is 10-bit.
• 10-bit multichannel Analog to Digital converter.
• Synchronous Serial Port (SSP) with SPI (Master Mode) and I2C (Master/Slave).
• Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-bit address detection.
• Parallel Slave Port(PSP) 8-bit wide, with external RD,WR and CS controls(40/44-pin only)
• Brown out detection circuitry for Brown-Out-Reset (BOR)
Applications
• Industrial control
• Medical system
• Access control
• Point-of-sale
• Communication gate way
• General purpose applications