;8 bit LCD routines with check busy flag before sending data, command to LCD LCD DATA P1 ;define LCD data port on port 1 BUSY BIT LCD.7 ;define LCD busy flag E BIT P2.2 ;define LCD enable pin on port 2.2 RS BIT P2.0 ;define LCD register select pin on port 2.0 RW BIT P2.1 ;define LCD read/write pin on port 2.1 ORG 00H LCD_INIT: MOV A,#38H ;2 line 5x7 ACALL COMMAND MOV A,#0CH ;LCD on cursor on ACALL COMMAND MOV A,#01H ;clear LCD ACALL COMMAND MOV A,#06H ;shift cursor right ACALL COMMAND DISPLAY: MOV A,#81H ACALL COMMAND MOV DPTR,#TEST ACALL DISP_STRING MOV A,#0C1H ACALL COMMAND MOV DPTR,#TEST+0EH ACALL DISP_STRING HERE: SJMP HERE COMMAND: ACALL READY ;is LCD ready? MOV LCD,A ;issue command code CLR RS ;RS=0 for command CLR RW ;R/W=0 to write to LCD| SETB E ;E=1 for H-to-L pulse CLR E ;E=0 ,latch in RET DATA_DISPLAY: ACALL READY ;is LCD ready? MOV LCD,A ;issue data SETB RS ;RS=1 for data CLR RW ;R/W=0 to write to LCD SETB E ;E=1 for H-to-L pulse CLR E ;E=0 ,latch in RET READY: SETB BUSY ;make P1.7 input port CLR RS ;RS=0 access command reg SETB RW ;R/W=1 read command reg ;read command reg and check busy flag BACK: CLR E ;E=1 for H-to-L pulse SETB E ;E=0 H-to-l pulse JB BUSY,BACK ;stay until busy flag=0 RET DISP_STRING: CLR A ;A=0 MOV R7,#00H ;R7=0 NEXT_CHAR: INC R7 ;R7+1 MOVC A,@A+DPTR ACALL DATA_DISPLAY MOV A,R7 CJNE R7,#0EH,NEXT_CHAR RET TEST: DB "8-Bit LCD Test","By 80C51 MCU's" END
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List of topics: 8051
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