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PIC Controller

PIC Controller. Instruction format. RISC (Reduced Instruction Set Computing) or ‘Risk’. Is a CPU design method that gives an instruction set reduced both in size and complexity of addressing modes . Every small operation needs an instruction.

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PIC Controller

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  1. PIC Controller Instruction format

  2. RISC (Reduced Instruction Set Computing) or ‘Risk’ • Is a CPU design method that gives an instruction set reduced both in size and complexity of addressing modes. • Every small operation needs an instruction. • Load data from memory to working register, Add some data, Store the data in to memory – needs 3 instructions. • Ex. ARM, PIC, AVR, SPARC, etc.

  3. CISC (Complex Instruction Set Computing) or ‘Sisk’ • Is a microprocessor architecture that gives an instruction set which can execute many low level operations. • Load data from memory to working register, Arithmetic/Logical operation, Store data into memory – can be done in 1 instruction. • Ex. Intel, AMD, Motorola, etc.

  4. Introduction • Instructions do data transfer between the data memory [SFR (control/configuration registers), GPR, repetitive registers] and working register (W). • Instructions do Arithmetic, logical operations on the data. • Instruction can check the status of each operation and decide the next operation using the status register.

  5. Working Register (Accumulator) • Whenever a double operand instruction is executed, one operand comes from the instruction or from a register. The other operand comes from a register called working register. • This is a special register in CPU (not a part of data memory) • This is the default destination for any instruction.

  6. StatusRegister

  7. StatusRegister

  8. Introduction • Each instruction is 14 bit wide • Opcode • Specifies instruction type • One or two operands • Specifies operation of instruction • Three basic categories • Byte oriented • Bit oriented • Literal and control operations

  9. Instruction Formats

  10. OPCODE Field Descriptions

  11. Byte Oriented Operations

  12. Instructions

  13. Assembly Language • Each instruction typically consists of an operation or opcode plus zero or more operands. • A label can be specified before each instruction. • Labels are case sensitive and start with an alphabetic or underscore character only.

  14. Assembly Language • The instructions must be written in proper case. The MPASM is case sensitive. • All function registers and their bits are specified in upper case, because upper case is used in the included PIC file. • Use comment for every instruction.

  15. Assembly Language • Sample Instruction: NEXTMOVFFSR,W;move the contents of FSR to W. • ‘NEXT’ is called the Label. • ‘MOVF’ is called the Mnemonic. • ‘FSR,W’ are called the Operands. • ‘;move thecontents….’ is the Comment.

  16. Assembly Language • Sample Instruction: _OP1IORLW0xFF;Inclusive OR the contents of W with 1111 1111. • ‘_OP1’ is called the Label. • ‘IORLW’ is called the Mnemonic. • ‘0xFF’ are called the Operands. • ‘;InclusiveOR the….’ is the Comment.

  17. Assembler Directives • An assembler directive is a command given to an assembler. • Looks like assembly instructions • These directives may do anything from telling the assembler to include other source files, to allocate memory for constant data, etc. • Specific for each assembler software • Ex: RIGHTEQU1;equ is an assembler directive.

  18. Program Structure: • All programs must have the following structure. List p=16f877A ; List directive mentioning the PIC ; Microcontroller part number #include‘C:\my_name\pic_lab\P16f877A.inc’ ; file having standard definitions of SFR’s of this PIC ORG 0x20 ; The address 0x20 at which the ; next instruction 'goto' will be stored GOTO start ; Go to the beginning of main program start --------------------------- ;Program Logic --------------------------- ;Program Logic END

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