Loop and Delay

Loops and Delay functions/152120201044.asm

@@ -0,0 +1,112 @@
+    LIST 	P=16F877A
+    INCLUDE	P16F877.INC
+    __CONFIG _CP_OFF &_WDT_OFF & _BODEN_ON & _PWRTE_ON & _XT_OSC & _WRT_ENABLE_OFF & _LVP_OFF & _DEBUG_OFF & _CPD_OFF
+    radix	dec
+
+    ; Reset vector
+    org 0x00
+    ; ---------- Initialization ---------------------------------
+    
+    BANKSEL TRISB ; Select the Bank where TRISB is located (Bank 1)
+    MOVLW 0xFF
+    MOVWF TRISB ; Make all pins of PORTB as input pins
+    CLRF TRISD ; Make all pins of PORTD as output pins
+    BANKSEL PORTD ; Select the Bank where PORTB is located (Bank 0)
+    CLRF PORTD ; Turn off all LEDs
+    
+    ; ---------- Your code starts here --------------------------
+    
+    fib0    EQU	    0x20
+    fib1    EQU	    0x21
+    fib	    EQU	    0x22
+    i	    EQU	    0x23
+    N	    EQU	    0x24
+    temp    EQU     0x25
+     
+     
+    MOVLW	1		    ; WREG = 1
+    MOVWF	fib0		    ; fib0 = WREG
+
+    MOVLW	2		    ; WREG = 2
+    MOVWF	fib1		    ; fib1 = WREG
+    
+    MOVLW	2		    ; WREG = 2
+    MOVWF	i		    ; i = WREG
+
+    MOVLW	13		    ; WREG = 13
+    MOVWF	N		    ; N = WREG
+    
+   
+;for loop
+loop_begin:	
+	; Check if i<=N? If not, we will terminate the loop
+	; The loop terminates when i > N or N < i.
+	
+	MOVF	i, W		    ; WREG = i
+	SUBWF	N, W		    ; WREG = N - i
+	BTFSS	STATUS, C	    ; No carry means N < i. Carry means N >= i or i <= N
+	GOTO	loop_end	    ; when i > N, the loop terminates
+	
+loop_body:
+    
+        ;zib = (zib1 & 0x3f) + (zib0 | 0x05)
+	
+	MOVF	fib1, W		    ; WREG = fib1
+	ANDLW	0x3f                ; WREG = fib1 & 0x3f
+	MOVWF	temp                ; temp = WREG
+	
+	MOVF	fib0, W		    ; WREG = fib0
+	IORLW	0x05                ; WREG = fib0 | 0x05
+	ADDWF	temp, W		    ; WREG += temp
+	MOVWF   fib                 ; fib = WREG
+   
+	MOVF	fib1, W		    ; WREG = fib1
+	MOVWF   fib0                ; fib0 = WREG
+	
+	MOVF	fib, W		    ; WREG = fib
+	MOVWF   fib1                ; fib1 = WREG
+	MOVF	fib, W		    ; WREG = fib
+	MOVWF   PORTD
+	
+	CALL    Delay250ms
+	INCF	i, F		    ; i++
+	
+	button_3:     ; while (PORTB3 == 1)
+	BTFSC	PORTB, 3
+	GOTO	button_3
+	GOTO	loop_begin
+	
+		
+loop_end:
+    
+;------------------------------------------------------------------------------
+; Waste 250ms in a loop
+;------------------------------------------------------------------------------
+Delay250ms:
+	k	    EQU	    0x70		    ; Use memory slot 0x70
+	j	    EQU	    0x71		    ; Use memory slot 0x71
+	MOVLW	    d'250'		    
+	MOVWF	    k			    ; k = 250
+	
+Delay250ms_OuterLoop:
+	MOVLW	    d'250'
+	MOVWF	    j			    ; j = 250
+	
+Delay250ms_InnerLoop:	
+	NOP
+	DECFSZ	    j, F		    ; j--
+	GOTO	    Delay250ms_InnerLoop
+
+	DECFSZ	    k, F		    ; k--
+	GOTO	    Delay250ms_OuterLoop    
+	RETURN
+	
+	
+    ; ---------- Your code ends here ----------------------------    
+    MOVWF   PORTD    	; Send the result stored in WREG to PORTD to display it on the LEDs
+    
+LOOP    GOTO    $	; Infinite loop
+    END
+
+
+