;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;   This is a base program for clocking in bitmaps to the SED1330 on a 240x320 LCD display
;   using 8051 assembly code.  
;   
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		;
START:    		MOV     30H,#3EH       	;SETS UP THE INNER LOOP TO 62
	  	MOV     31H,#01H       	;SETS UP FOR NULL DATA
	  	LCALL CK_DATA        	;GO GET DATA
	  	MOV     B,#0F0H        	;SETS UP INNER LOOP FOR 240 LINES OF DATA 
	  	MOV     32H,#008H      	;SETS LOWER CURSOR ADDRESS (address where program ends/bitmap begins) 
	  	MOV     33H,#02AH      	;SETS UPPER CURSOR ADDRESS
DO_OVER:  	PUSH    B              		;STORE VALUE
	 	MOV     30H,#28H       	;SETS UP THE INNER LOOP TO 40 CHARACTERS PER LINE
	 	MOV     31H,#00H       	;SETS UP FOR VALID DATA
	 	LCALL SET_CUR        	;SETS THE INITIAL ADDRESS ON DISPLAY
	 	LCALL CK_DATA        	;GO GET DATA
	 	POP      B              		;RECALLS INNER LOOP
	 	DJNZ   B,CONTINUE     	;IF NOT ZERO, THEN REDO (moving up one line on display if doing over)
		RET                    		;
CONTINUE:	MOV    A,0D0H         		;RECALL CARRY FLAG
	  	ANL     A,#7FH         		;CLEAR THE CARRY FLAG
	  	MOV    0D0H,A         		;STORE FLAG
	  	MOV    A,32H          		;RECALL LOWER CURSOR ADDRESS
	 	SUBB   A,#28H         		;SUBTRACT 40 FROM THIS ADDRESS TO MOVE UP ONE LINE
	 	MOV    32H,A          		;RESTORE THE NEW LOWER ADDRESS
	  	MOV    A,0D0H        	 	;RECALL CARRY FLAG
	  	ANL     A,#80H         		;STRIP OFF CARRY FLAG
	  	CJNE    A,#80H,NO_CARRY 	;SEE IF FLAG IS SET (if set then must bump down higher address by 1)
	  	MOV    A,33H          		;RECALL UPPER CURSOR ADDRESS
	  	SUBB   A,#01H         		;SUBTRACT 1 FORM UPPER
	  	MOV    33H,A          		;RESTORE THE VALUE
NO_CARRY: 	LJMP   DO_OVER        	;DO INNER ROUTINE OVER AGAIN
CK_DATA:  	MOV     A,31H          		;RECALL BYTE FOR NULL OR VALID DATA
	  	CJNE    A,#00H,GET_DATA 	;SEE IF NULL DATA OR NOT (selects appropriate subroutine)
DATA_IN:  	LCALL DATA_ARM       	;GET THE VALID DATA
	  	LCALL WRCHAR         	;SEND IT TO THE DISPLAY
	  	DJNZ     30H,DATA_IN    	;COMPARE LOOP AND DECREMENT UNTIL ZERO
	  	RET                    		;
GET_DATA: 	LCALL DATA_ARM      	;GET THE NULL DATA
	  	DJNZ    30H,GET_DATA   	;SEE IF INNER LOOP IS ZERO
     		RET                    		;
SET_CUR:  	MOV     B,#46H         		;SET ADDRESS POINTER
	  	LCALL WRCMD          	;CLOCK IN
	  	MOV     B,32H          		;RECALL THE LOWER CURSOR POSITION
	  	LCALL  WRDATA         	;CLOCK IN
	  	MOV     B,33H          		;RECALL THE HIGHER CURSOR POSITION
	  	LCALL  WRDATA         	;CLOCK IN
	  	RET                    		;
DATA_ARM: 	MOV     82H,34H        	;MOV LOWER DATA POINTER ON THE STACK
	  	MOV     83H,35H        	;MOV HIGHER DATA POINTER ON THE STACK
	  	MOV     A,#00H         		;CLEAR OUT REGISTER FOR TRUE DATA POINTER
	  	MOVC  A,@A+DPTR      	;GET THE DATA POINTED TO BY THE DATA POINTER
	  	MOV     B,A            		;SWAP DATA TO "B" REGISTER
	  	INC       DPTR           		;INCREMENT THE DATA POINTER
	  	MOV     34H,82H        	;RESTORE LOWER DATA (includes increment)
	  	MOV     35H,83H        	;RESTORE HIGHER DATA
	  	RET                    		;
WRCHAR:   	PUSH    B              		;STORE DATA
	  	MOV     B,#042H        	;SETS WRITE DATA COMMAND
	  	LCALL  WRCMD          	;CLOCK IN
	  	POP       B              		;RECALL DATA
	  	XRL      B,#0FFH        	;INVERSE DATA TO PREVENT INVERSE VIDEO
	  	LCALL  WRDATA         	;GO CLOCK IN
	  	RET                    		;
WRDATA:  	MOV     0C0H,#03H      	;SETS WR AND RD HIGH AND A0 LOW
	  	MOV     0C0H,#01H      	;STROBE WR LOW
	  	MOV     090H,B         		;PUTS DATA ON PORT 1
	  	MOV     0C0H,#03H      	;STROBE WR HIGH
	  	RET                    		;
WRCMD:    	MOV     0C0H,#07H      	;SETS WR, RD, AND A0 HIGH
	  	MOV     0C0H,#05H      	;STROBE WR LOW
	  	MOV     090H,B         		;PUTS COMMAND ON PORT 1
	  	MOV     0C0H,#07H      	;STROBE WR HIGH
	  	RET                    		;
	  	.END