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PIC16F877 Instruction Set

PIC – INSTRUCTION SET

Dr. Charles J. Kim

Howard University

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F877 Instruction Set� 14-Bit Word� Byte-Oriented Instruction

�F: File Register (or RAM)�D: Destination

⌧D=0: Destination � W⌧D=1: Destination � File Register

� Bit-Oriented Instruction�B: Bit Field�F: Register File where the Bit is located

� Literal and Control Operation�K: 8-bit constant

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General Form of Instruction

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Instruction List

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Destination of the result�D=0: Destination � W�D=1: Destination � File Register (Default)

�addwf PORTD ; ⌧Add content of PORTD to content of the W and

store the result back into PORTD

�addwf PORTD, 0 ;⌧Add content of PORTD to content of the W and

store the result into W

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Register Addressing Modes�Immediate Addressing

⌧(ex) MOVLW 0x0F�Direct Addressing

�Uses 7 bits of 14 bit instruction to identify a register file address

�8th and 9th bit comes from RP0 and RP1 bits of STATUS register.

� (ex) SSPCON EQU 0x14STATUS EQU 0x03SSPSTAT EQU 0x94BCF STATUS, 0x05BCF SSPCON, 0x01BSF STATUS, 0x05BCF SSPSTAT, 0x02

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Direct Addressing

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Indirect Addressing� INDF register

�Any instruction using the INDF actually accesses the register pointed to by the File Select Register (FSR).

� A 9-bit EA is obtained by concatenating the 8-bit FSR register and the IRP bit(STATUS<7>)

� Example: Erase the RAM section of 0x20-0x2F

Movlw 0x20; pointerMovwf FSR

Next clrf INDF

incf FSRbtfss FSR, 4

goto next

……

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Direct vs. Indirect Addressing

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Instruction Sets –description convention

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addlw

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addwf

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andlw

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andwf

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Bcf & bsf

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btfsc

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Btfss

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Call

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CLRF & CLRW

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COMF & DECF

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DECFSZ

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GOTO & INCF

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INCFSZ

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IORLW & IORWF

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MOVLW & MOVF

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MOVWF & NOP

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RETFIE & RETLW

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RETURN

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RLF & RRF

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SUBLW & SUBWF

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SWAPF & XORLW

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XORWF