Pic microcontroller architecture

Pic microcontroller architecture

• 1.
  PIC MICROCONTROLLER ARCHITECTURE PIC microcontrollerarchitecture Bock diagram Advantages
• 2.
  ARCHITECTURE:  IC Microcontrollerarchitecture is based on Harvard architecture and supports RISC architecture (Reduced Instruction Set Computer).  PIC microcontroller architecture consists of memory organization (RAM, ROM, STACK), CPU, timers, counter, ADC, DAC, serial communication, CCP module and I/O ports.  PIC microcontroller also supports the protocols like CAN, SPI, UART for interfacing with other peripherals.
• 3.
  PIC MICROCONTROLLER ARCHITECTURE BLOCKDIAGRAM
• 4.
  CPU (Central ProcessingUnit): PIC microcontroller’s CPU consists of 1. Arithmetic logic unit (ALU) 2. Memory unit (MU) 3. Control unit (CU) 4. Accumulator  ALU is used for arithmetic operations and for logical decisions.  Memory is used for storing the instructions after processing.  Control unit is used to control the internal and external peripherals which are connected to the CPU and accumulator is used for storing the results. MEMORY ORGANIZATION:  PIC microcontroller memory module consists of mainly 3 types of memories: 1. Program memory 2. Data memory
• 5.
  PROGRAM MEMORY:  Itcontains the written program after we burned it in microcontroller.  Program Counter executes commands stored in the program memory, one after the other.  PIC microcontroller can have 8K words x 14 bits of Flash program memory that can be electrically erased and reprogrammed.  Whenever we burn program into the micro, we erase an old program and write a new one.
• 6.
  DATA MEMORY:  Itis a RAM type which is used to store the data temporarily in its registers.  The RAM memory is classified into banks. Each bank extends up to 7Fh (128 bytes).  Number of banks may vary depending on the microcontroller.  PIC16F84 has only two banks. Banks contain Special Function Registers (SFR) and General Purpose Registers (GPR).  The lower locations of each bank are reserved for the Special Function Registers and upper locations are for General Purpose Registers.
• 7.
  General Purpose Registers(GPR): oThese registers don’t have any special function. o These are used for general purpose for multiplying, addition or subtraction and then storing the results in other registers. o CPU can easily access the data in these registers. Special Function Registers (SFR): oThese registers are used for special purposes and they cannot be used as normal registers. oTheir function is set at the time of manufacturing. o They perform the function assigned to them and user cannot change the function of SFR. o Three important SFRs for programming are: 1. STATUS register : It changes the bank 2. PORT registers : It assigns logic values 0 or 1 to the ports 3. TRIS registers : It is a data direction register for input and output
• 8.
  DATA EEPROM:  Thismemory allows storing the variables as a result of burning the written program.  It is readable and writable during normal operation (over the full VDD range).  This memory is not directly mapped in the register file.  It is indirectly addressed through the SFRs.  There are six SFRs which are used to read and write to this memory (EECON1, EECON2, EEDATA, EEDATH, EEADR, EEADRH).
• 9.
  ADVANTAGES  Small instructionset to learn.  RISC architecture.  Built-in oscillator with selectable speeds.  Easy entry level, in-circuit programming plus in- circuit debugging PIC kit units available for less than $50.  Inexpensive microcontrollers.  Wide range of interfaces including I²C, SPI, USB, USART, A/D, programmable comparators, PWM, LIN, CAN, PSP, and Ethernet.  Availability of processors in DIL package make them easy to handle for hobby use.