8051 Program – 1ms delay

; 1ms delay
; the crystal frequency is given as 12 MHz.
; Make a subroutine that will generate delay
; of exact 1 ms. Use this delay to
; generate square wave of 50 Hz on pin P2.0
	ORG 0H
LOOP:	SETB P2.0
	MOV R6, #0AH
	ACALL DELAY
	CLR P2.0
	MOV R6, #0AH
	ACALL DELAY
	SJMP LOOP
DELAY:
LP2:	MOV R7, #0FAH
LP1:	NOP	; 1 CYCLE
	NOP	; 1+1=2 CYCLES
	DJNZ R7, LP1	; 1+1+2 = 4 CYCLES
	DJNZ R6, LP2	; 4×250 = 1000 CYCLES = 1000 µS = 1 MS
	RET
	END

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List of topics: 8051

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