PIC16F627A PROJECT

NINO · May 13, 2024

HI GUYS I NEED YOUR HELP WITH THIS PROJECT MY SEGMENT DOES NOT DISPLAY PROPERLY

Nigel Goodwin · May 13, 2024

For a start post your code, but for a clue you can use a data table to correct the pin connections for the seven segments.

aliarifat794 · May 13, 2024

I could not find any tutorial that will directly help you. But here is a video series on PIC16F877A in assembly language. If you need to clear up with the basics, this may help.

NINO · May 13, 2024

Nigel Goodwin said:
For a start post your code, but for a clue you can use a data table to correct the pin connections for the seven segments.

;-- Define the title, device and any files that need to be included

PROCESSOR 16F627A ; processor type

#include <xc.inc>
#include "pic16f627A.inc"

PSECT code, abs

; Define variables to store color values for each color and ADC channel combination
D1 EQu 0x40 ;looop register 2
D2 EQU 0x41 ; loop register 1
D3 EQU 0x42 ;loop register 3

; Reset vector
org 0x00

GOTO INIT

INIT:
;Oscillator
BSF OSCF ; SET Fosc = 4MHz
;Tis = 1?s
;PORTA
BSF STATUS,5 ; Bank 1
BSF TRISA, 0 ; Set RA0 as INput
BSF TRISA, 1 ; Set RA1 as INput
BCF STATUS,5 ; Bank 0

;PORTB
BSF STATUS,5 ; Bank 1
CLRF TRISB ; Set PORTA as output
CLRF PORTB
BCF STATUS,5 ; Bank 0

MAIN:
CALL zero
BTFSS PORTA, 0
;GOTO BACK9
GOTO MAIN

back_1:
call DELAY_1s
CALL one ; DISPLAY 1
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_2;
GOTO MAIN ; BACK TO ZERO

back_2:
call DELAY_1s
CALL two ; DISPLAY 2
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_3
GOTO back_1 ;; BACK TO 1

back_3:
call DELAY_1s
CALL three ; DISPLAY 3
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_4 ; next
GOTO back_2 ;; BACK TO 2

back_4:
call DELAY_1s
CALL four ; DISPLAY 4
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_5 ; next
GOTO back_3 ;; BACK TO 3

back_5:
call DELAY_1s
CALL five ; DISPLAY 5
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_6 ; next
GOTO back_4 ;; BACK TO 6

back_6:
call DELAY_1s
CALL six ; DISPLAY 6
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_7 ; next
GOTO back_5 ;; BACK TO 5

back_7:
call DELAY_1s
CALL seven ; DISPLAY 7
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_8 ; next
GOTO back_6 ;; BACK TO 6

back_8:
call DELAY_1s
CALL eight ; DISPLAY 8
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO back_9 ; next
GOTO back_7 ;; BACK TO 7

back_9:
call DELAY_1s
CALL nine ; DISPLAY 9
BTFSS PORTA, 0
BTFSS PORTA, 1
GOTO MAIN; next
GOTO back_8 ;; BACK TO 8

GOTO MAIN

zero:
MOVLW 00111111B
MOVWF PORTB
RETURN
one:
MOVLW 00110000B
MOVWF PORTB
RETURN
two:
MOVLW 01011011B
MOVWF PORTB
RETURN
three:
MOVLW 01001111B
MOVWF PORTB
RETURN
four:
MOVLW 01110010B
MOVWF PORTB
five:
MOVLW 01101100B
MOVWF PORTB
RETURN
six:
MOVLW 01111101B
MOVWF PORTB
RETURN
seven:
MOVLW 00000111B
MOVWF PORTB
RETURN
eight:
MOVLW 01111111B
MOVWF PORTB
RETURN
nine:
MOVLW 01101111B
MOVWF PORTB
RETURN

DELAY_1s:
; T = 4xD1xD2xD3 x Tis
MOVLW 16 ; 1cy
MOVWF D3 ; 1cy
go1: ;outer loop
;===========================;
MOVLW 255 ; 1cy
MOVWF D2 ; 1cy
go2: ;inner loop ;
; Nesting location ;
MOVLW 255 ; 1cy
MOVWF D1 ; 1cy

go3:
DECFSZ D1 ; 1cy
GOTO go3 ; 2cy

DECFSZ D2 ; 1cy
GOTO go2 ; 2cy
;============================;
DECFSZ D3 ; 1cy
GOTO go1 ; 2cy
RETURN ; 2cy

END

Les Jones · May 13, 2024

Here is an example of using a data table.

Code:

;-----------------------------------------------------------------------------
;
; Segment patterns
;
;-----------------------------------------------------------------------------
;  These values are for common anode displays

        ORG    0x100        ;To avoid crossing a boundry in this table.

HEX2SEGMENTS  
  ; Note enter this subroutine with the value to be converted to the segment bit pattern in the "W" register
  ;on exiting the subroutine "W" contains the bit pattern to be sent to the 7 segments.
        CLRF    PCLATH
        INCF    PCLATH, F    ;Set PCLATH to 0x01 to point to this page

        ANDLW   b'00001111'      ;Use only lower nibble
                ADDWF   PCL,F           ;Add offset to current PC

;        *** These bit patterns could be changed to assign segments to different I/O pins to make board layout easier ***


;These bit patterns are for the following segment to bit assignments


;    A    RB0
;    B    RB1
;    C    RB2
;    D    RB4
;    E    RB5
;    F    RB6
;    G    RB7

SEGMENTS        
                RETLW   b'10000000'      ;0    NOTE low to illuminate segment
                RETLW   b'11110001'      ;1
                RETLW   b'01000100'      ;2
                RETLW   b'01100000'      ;3
                RETLW   b'00110001'      ;4
                RETLW   b'00100010'      ;5
                RETLW   b'00000010'      ;6
                RETLW   b'11110000'      ;7
                RETLW   b'00000000'      ;8
                RETLW   b'00100000'      ;9
                RETLW   b'00010000'      ;A
                RETLW   b'00000011'      ;B
                RETLW   b'10000110'      ;C
                RETLW   b'01000001'      ;D
                RETLW   b'00000110'      ;E
                RETLW   b'00010110'      ;F

;                    -----------------------------------

Les.

Dan Soze · May 14, 2024

To the OP:
There is quite a lot missing from the code in your post#4.

This is what a complete example that builds without warnings or errors looks like:

Code:

;
; File:     main.S
; Target:   PIC16F627A
; Author:   dan1138
; Date:     2024-05-14
; Compiler: pic-as(v2.40)
; IDE:      MPLABX v6.00
;
; Description:
;
;   Answer for homework see: https://www.electro-tech-online.com/threads/pic16f627a-project.166131/
;
;                    PIC16F627A
;            +----------:_:----------+
;       <> 1 : RA2               RA1 : 18 <> SW2
;       <> 2 : RA3               RA0 : 17 <> SW1
;       <> 3 : RA4(*)       OSC1/RA7 : 16 <>
;   VPP -> 4 : RA5/MCLRn    OSC2/RA6 : 15 <>
;   GND -> 5 : VSS               VDD : 14 <- 5v0
; LED_a <> 6 : RB0           PGD/RB7 : 13 <>       /PGD
; LED_b <> 7 : RB1/RX/DT     PGC/RB6 : 12 <> LED_g /PGC
; LED_c <> 8 : RB2/RX/CK         RB5 : 11 <> LED_f
; LED_d <- 9 : RB3/CCP1      PGM/RB4 : 10 <> LED_e
;            +-----------------------:
;                     DIP-18
; Notes:
;  (*) RA4 is an open drain output. Requires an external pull-up for output.
;
;
; Add this line in the project properties box, pic-as Global Options -> Additional options:
;   -Wa,-a -Wl,-pPor_Vec=0h,-pIsr_Vec=4h
;
    PROCESSOR   16F627A
    PAGEWIDTH   132
    RADIX       DEC
;
; Define the system oscillator frequency this code will setup
;
#define _XTAL_FREQ 4000000
;
; PIC16F627A Configuration Bit Settings
;
  CONFIG  FOSC = INTOSCIO       ; Oscillator Selection bits (INTOSC oscillator: I/O function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OSC1/CLKIN)
  CONFIG  WDTE = OFF            ; Watchdog Timer Enable bit (WDT disabled)
  CONFIG  PWRTE = OFF           ; Power-up Timer Enable bit (PWRT disabled)
  CONFIG  MCLRE = ON            ; RA5/MCLR/VPP Pin Function Select bit (RA5/MCLR/VPP pin function is MCLR)
  CONFIG  BOREN = OFF           ; Brown-out Detect Enable bit (BOD disabled)
  CONFIG  LVP = OFF             ; Low-Voltage Programming Enable bit (RB4/PGM pin has digital I/O function, HV on MCLR must be used for programming)
  CONFIG  CPD = OFF             ; Data EE Memory Code Protection bit (Data memory code protection off)
  CONFIG  CP = OFF              ; Flash Program Memory Code Protection bit (Code protection off)

#include <xc.inc>
;
; Power-On-Reset entry point
;
    PSECT   Por_Vec,global,class=CODE,delta=2
    global  resetVec
resetVec:
    goto    main
;
;   Interrupt vector and handler
    PSECT   Isr_Vec,global,class=CODE,delta=2
    retfie                      ; Return from interrupt
;
; Application
;
    psect   MainData,global,class=RAM,space=1,delta=1,noexec
    global  SW_Sample,SW_Stable,SW_Change,SW_Bounce
    global  DigitCount

#define SW_BOUNCE_TIME 5
SW_Sample:      ds  1
SW_Stable:      ds  1
SW_Change:      ds  1
SW_Bounce:      ds  1
#define MAX_DIGIT_COUNT 9
#define MIN_DIGIT_COUNT 0
DigitCount:     ds  1
;
; Data common to all banks
    psect   TMR0data,global,class=COMMON,space=1,delta=1,noexec
    global  T0_Tick,delay_1s_count

; Define how many TIMER0 counts in one 250Hz period
; (Forc/4/TMR0_prescale/250Hz)
#define T0_250HZ (_XTAL_FREQ/4/32/250)
T0_Tick:        ds  1
delay_1s_count: ds  1

    PSECT   MainCode,global,class=CODE,delta=2
main:
    clrf    INTCON
    movlw   0x07
    movwf   CMCON
    banksel SW_Sample
    clrf    SW_Sample
    clrf    SW_Stable
    movlw   SW_BOUNCE_TIME
    movwf   SW_Bounce
    clrf    DigitCount
    banksel OPTION_REG
    movlw   0xD4        ; TIMER0 clock source is Fosc/4, prescale 1:32
    movwf   OPTION_REG
    bsf     TRISA,TRISA_TRISA0_POSITION
    bsf     TRISA,TRISA_TRISA1_POSITION
    clrf    TRISB
    banksel PORTB
    clrf    PORTB
    clrf    T0_Tick
;
; Process loop
;
AppLoop:
    call    SW_Poll
    iorlw   0
    btfsc   STATUS,STATUS_Z_POSITION
    goto    AppLoop    
;
; Decide what to do when switches change state
    movf    SW_Stable,W
    andlw   0x03
    btfsc   STATUS,STATUS_Z_POSITION
    goto    AppLoop         ; Both switches open

    xorlw   0x03
    btfsc   STATUS,STATUS_Z_POSITION
    goto    AppLoop         ; Both switches closed

    clrw                    ; 
SW_check_SW1:
    btfss   SW_Change,0
    goto    SW1_no_change
    bcf     SW_Change,0
    btfsc   SW_Stable,0
    call    SW1_Action      ; SW1 closed
SW1_no_change:
    btfss   SW_Change,1
    goto    SW2_no_change
    bcf     SW_Change,1
    btfsc   SW_Stable,1
    call    SW2_Action      ; SW2 closed
SW2_no_change:
;
; WREG is zero when not button action occurs 
SW_ActionRepeat:
    iorlw   0
    btfsc   STATUS,STATUS_Z_POSITION    ; Skip if burron action occurred
    goto    AppLoop
;
; Display count
    call    LookUpSegments
    banksel PORTB
    movwf   PORTB
    call    delay_1s
;
; Check if a button changed during wait
    banksel SW_Change
    movf    SW_Change,W
    btfss   STATUS,STATUS_Z_POSITION
    goto    AppLoop         ; button changed stop action
;
; Repeate action if button pressed
    clrw                    ; 
    btfsc   SW_Stable,0
    call    SW1_Action
    btfsc   SW_Stable,1
    call    SW2_Action
    goto    SW_ActionRepeat
;
SW1_Action:
    movf    DigitCount,W
    xorlw   MAX_DIGIT_COUNT
    movlw   MIN_DIGIT_COUNT
    btfss   STATUS,STATUS_Z_POSITION
    incf    DigitCount,W
    movwf   DigitCount    
    retlw   1
;
SW2_Action:
    movf    DigitCount,W
    xorlw   MIN_DIGIT_COUNT
    movlw   MAX_DIGIT_COUNT
    btfss   STATUS,STATUS_Z_POSITION
    decf    DigitCount,W
    movwf   DigitCount    
    retlw   1
;
; Poll buttons
; Returns: WREG = 0, no change
;          WREG = 1, button changed
SW_Poll:
    banksel TMR0            ; Poll TIMER0 to wait for 4 milliseconds to elapse
    movf    T0_Tick,W
    subwf   TMR0,W
    addlw   -T0_250HZ
    btfss   STATUS,STATUS_C_POSITION
    goto    SW_Poll
    movlw   T0_250HZ
    addwf   T0_Tick,F
;
; Sample switch inputs
    banksel PORTA
    clrw
    btfsc   PORTA,0     ; skip if SW1 open
    iorlw   0b00000001  ; Show SW1 pressed
    btfsc   PORTA,1     ; skip if SW2 open
    iorlw   0b00000010  ; Show SW2 pressed
    banksel SW_Sample
    xorwf   SW_Sample,W
    andlw   0x03
    btfss   STATUS,STATUS_Z_POSITION
    goto    SW_Bouncing
    decfsz  SW_Bounce,F
    goto    SW_Bounce_Done
SW_Bouncing:
    xorwf   SW_Sample,F
    movlw   SW_BOUNCE_TIME
    movwf   SW_Bounce
    retlw   0
SW_Bounce_Done:
    movf    SW_Sample,W
    xorwf   SW_Stable,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0
    iorwf   SW_Change,F
    xorwf   SW_Stable,F
    retlw   1
;
;
delay_1s:
    movlw   250     ; number of 250Hz cycles in one second    
    movwf   delay_1s_count
delay_1s_Loop:
    call    SW_Poll
    decfsz  delay_1s_count,F
    goto    delay_1s_Loop
    return
;
; The student must fix this function
; to return the correct bits to light
; the 7-segment display correctly
;
LookUpSegments:
    banksel DigitCount
    movlw   0
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00000001      ; seven-segments for 0
    movlw   1
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00000010      ; seven-segments for 1
    movlw   2
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00000010      ; seven-segments for 2
    movlw   3
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00000100      ; seven-segments for 3
    movlw   4
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00001000      ; seven-segments for 4
    movlw   5
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b00100000      ; seven-segments for 5
    movlw   6
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b01000000      ; seven-segments for 6
    movlw   7
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b10000000      ; seven-segments for 7
    movlw   8
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b10000001      ; seven-segments for 8
    movlw   9
    xorwf   DigitCount,W
    btfsc   STATUS,STATUS_Z_POSITION
    retlw   0b10000010      ; seven-segments for 9
    retlw   0
;
    END     resetVec

Note that I did not put much in the way of comments on how this code actually works. The function to convert a count from 0 to 9 to 7-segments must be fixed because to image you posted of your assignment is so poor that how PORTB is connected to the LED 7-segment cannot be determined.

I did leave a bug in this code so there is a subtle flaw in how it works. So it does not quit do what your assignment says it should.

PIC16F627A PROJECT

NINO

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Nigel Goodwin

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NINO

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PIC16F627A PROJECT

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