Traffic Light Interface

Program

2.TRAFFIC  LIGHTS

; TRAFFIC LIGHT CONTROLLER INTERFACE

; The interface is connected over J4 of of trainer

; Traffic system moves from one state to other after a fixed delay

; This program starts at 2000H location

   OUTPUT  2500AD

        ORG     2000H

START:  MOV     AL,80H                 ; Initialisation of 8255 Mode 0

        MOV     DX,0FFE6H

        OUT     DX,AL                  ; All ports as o/p ports

AGAIN:  MOV     SI,2038H               ; Table of port values

NEXTST: MOV     AL,[SI]

        MOV     DX,0FFE0H

        OUT     DX,AL                  ; PortA value

        INC     SI

        ADD     DX,2

        MOV     AL,[SI]

        OUT     DX,AL                  ; PortB value

        INC     SI

        ADD     DX,2

        MOV     AL,[SI]

        OUT     DX,AL                  ; PortC value

        INC     SI

        CALL    DELAY                  ; Calling Delay routine

        CMP     SI,2044H               ; Checking for the end of the data values

        JNZ     NEXTST

        JMP     AGAIN

DELAY:  MOV     CX,0FFH                ; Delay routine

DLY5:   PUSH    CX

        MOV     CX,03FFH

DLY10:  NOP

        LOOP    DLY10

        POP     CX

        LOOP    DLY5

        RET

        ORG     2038H

        PORTVALUES:     DB      88H,83H,F2H               

                                      DB      38H,88H,F4H             

                                      DB      83H,88H,F8H              

                                      DB      88H,38H,F1H                

                                      DB      00H