PIC Traffic Light Controller using PIC microcontroller 1.0

Traffic Light Controller using PIC microcontroller. The download contains the PIC asm code and the proteus simulation file.

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Circuit Diagram

Code

Code (Text):

1.           LIST    p=16F84 ; PIC16F844 is the target processor
2.  
3.           #include "P16F84.INC" ; Include header file
4.  
5.           CBLOCK 0x10  ; Temporary storage
6.               state
7.               l1,l2
8.           ENDC
9.  
10.           org    0              ; Start up vector.
11.           goto    setports        ; Go to start up code.
12.  
13.       org    4              ; Interrupt vector.
14. halt      goto    halt            ; Sit in endless loop and do nothing.
15.  
16. setports  clrw                    ; Zero in to W.
17.           movwf  PORTA          ; Ensure PORTA is zero before we enable it.
18.           movwf  PORTB          ; Ensure PORTB is zero before we enable it.
19.           bsf    STATUS,RP0      ; Select Bank 1
20.           clrw                    ; Mask for all bits as outputs.
21.           movwf  TRISB          ; Set TRISB register.
22.           bcf    STATUS,RP0      ; Reselect Bank 0.
23.  
24. initialise clrw                    ; Initial state.
25.           movwf  state          ; Set it.
26.  
27. loop      call    getmask        ; Convert state to bitmask.
28.           movwf  PORTB          ; Write it to port.
29.           incf    state,W        ; Increment state in to W.
30.           andlw  0x03            ; Wrap it around.
31.           movwf  state          ; Put it back in to memory.
32.           call    wait            ; Wait :-)
33.           goto    loop            ; And loop :-)
34.  
35.           ; Function to return bitmask for output port for current state.
36.           ; The top nibble contains the bits for one set of lights and the
37.           ; lower nibble the bits for the other set. Bit 1 is red, 2 is amber
38.           ; and bit three is green. Bit four is not used.
39. getmask    movf    state,W        ; Get state in to W.
40.           addwf  PCL,F          ; Add offset in W to PCL to calc. goto.
41.           retlw  0x41            ; state==0 is Green and Red.
42.           retlw  0x23            ; state==1 is Amber and Red/Amber
43.           retlw  0x14            ; state==3 is Red  and Green
44.           retlw  0x32            ; state==4 is Red/Amber and Amber.
45.  
46.           ; Function using two loops to achieve a delay.
47. wait      movlw  5
48.           movwf  l1
49.  
50. w1        call    wait2
51.           decfsz  l1
52.           goto    w1
53.  
54.           return
55.  
56.  
57. wait2      clrf    l2
58. w2        decfsz  l2
59.           goto    w2
60.           return
61.           END
62.