Instructions: MOV, DJNZ, RR, SJMP instruction format

Instructions: MOV, DJNZ, RR, SJMP

Department of Computer Science and Information Engineering, Chaoyang University of Technology

朝陽科技大學資工系

Speaker: Fuw-Yi Yang

Instructions: MOV, DJNZ, RR, SJMP instruction format

An Assembly language instruction consists of 4 fields:

[label:] mnemonic [operands] [;comment]

Top: MOV A, #00H ; move immediate data to register A MOV P0, A

Brackets ([ ], should not be typed in) indicate that a field is optional, and not all lines have them.

Instructions: MOV, DJNZ, RR, SJMP assembler directives

Some widely used directives are:

ORG (origin)

EQU (equate), Count EQU 25 MOV R3, #Count

DB (define byte), DATA1: DB 28 ; decimal data DATA2: DB 0FEH; Hex data

DATA3: DB 00110011B; Binary data

DATA4: DB “My name is yang” ; ASCII codes END

Instructions: MOV, DJNZ, RR, SJMP

MOV dest-byte, source-byte

1. MOV A, #data MOV A, #25H ; data is 25

2. MOV A, Rn (n = 0…7) MOV A, R3 ; data in register R3 3. MOV A, direct MOV A, 30H ; data in address 30H 4. MOV A, @Ri (i = 0 or 1) MOV A, @R0 ; data pointed by R0 5. MOV Rn, A 6. MOV direct, A 7. MOV @Ri, A 8. MOV Rn, #immediate 9. MOV Rn, A 10. MOV Rn, direct 11. MOV direct, #data 12. MOV direct, @Ri

Instructions: MOV, DJNZ, RR, SJMP DJNZ byte, target

1. DJNZ Rn (n = 0…7), target DJNZ R3, Here

Example: Count from 1 to 20 and send the count to P1.

CLR A ; A = 0

MOV R2, #20 ; R2 = 20 counter Back: INC A

MOV P1, A

DJNZ R2, BACK ; repeat if R2 not = zero

Instructions: MOV, DJNZ, RR, SJMP RR A

This rotates the bits of register A right.

Example:

MOV A, #01100110B ; A = 01100110 RR A ; A = 00110011 RR A ; A = 10011001

Instructions: MOV, DJNZ, RR, SJMP SJMP 8-bit address

Transfer control unconditionally to a new address.

Example: Location Object code

0100 ORG 100H 0100 803E SJMP OVER 0140 ORG 140 H 0140 7A0A OVER: MOV R2, #10 0142 7B64 AGAIN: MOV R3, #100 0144 00 BACK: NOP

0145 00 NOP