list p=16F684           ; list directive to define processor
    #include <p16f684.inc>  ; processor specific variable definitions
    __CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF & _CPD_OFF
    radix dec               ; default radix is decimal
    errorlevel -302         ; suppress warnings when accessing SFRs in bank 1
;****************************** Assignment Statements ****************************
; Set up two counters to count down a delay
COUNT1 EQU 20h  ; Available GPR at address 20h used for storing COUNT1
COUNT2 EQU 21h  ; Available GPR at address 21h used for storing COUNT2
;******************************* #define Preprocessor statements *****************
; Define the 'direction' TRISA configuration for all leds
#define TRISA_D01   B'00001111' ; D1 connected between RA4 and RA5
#define TRISA_D23   B'00101011' ; D2 connected between RA4 and RA5
#define TRISA_D45   B'00011011' ; D4 connected between RA4 and RA5
#define TRISA_D67   B'00111001' ; D7 connected between RA4 and RA5

;6427717
; Define the 'data output' PORTA setting for switching ON the LEDs D2 to D3
#define LED_D0_ON   B'00010000' ; Sending HIGH to D0
#define LED_D1_ON   B'00100000' ; Sending HIGH to D1
#define LED_D2_ON   B'00010000' ; Sending HIGH to D2
#define LED_D3_ON   B'00000100' ; Sending HIGH to D3
#define LED_D4_ON   B'00100000' ; Sending HIGH to D4
#define LED_D5_ON   B'00000100' ; Sending HIGH to D5
#define LED_D6_ON   B'00000100' ; Sending HIGH to D6
#define LED_D7_ON   B'00000010' ; Sending HIGH to D7

;****************************** Start of Program- Initial configuration
        org     0x000       ; Processor reset vector
        bcf     STATUS,RP0  ; Bank 0 selected
        movlw   07h         ; Set RA<2:0> to digital and
        movwf   CMCON0      ; Comparators turned OFF
        bsf     STATUS,RP0  ; Bank 1 selected
        clrf    ANSEL       ; Digital I/O selected
        movlw   B'00111111' ; Move in W - 0x3F - Set all I/O pins as digital inputs
        movwf   TRISA       ; Configure I/O ports
        clrf    INTCON      ; Disable all interrupts, clear all flags
        bcf     STATUS,RP0  ; Bank 0 selected
        clrf    PORTA       ; Clear all outputs
        movlw   0xff        ; First load a value of say, F0h in the W register
        movwf   COUNT2      ; Now move it to COUNT2 register

START
        bsf     STATUS,RP0      ; Bank 1 selected
        movlw   TRISA_D67       ; Configure LEDs D6 and D7 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D6_ON   ; Write '1' for D6 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D6
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        bsf     STATUS, RP0 ; Bank 1 selected
        movlw   TRISA_D45       ; Configure LEDs D4 and D5 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D4_ON   ; Write '1' for D4 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D4
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        bsf     STATUS, RP0 ; Bank 1 selected
        movlw   TRISA_D23       ; Configure LEDs D2 and D3 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D2_ON   ; Write '1' for D2 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D2
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        bsf     STATUS, RP0 ; Bank 1 selected
        movlw   TRISA_D67       ; Configure LEDs D6 and D7 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D7_ON   ; Write '1' for D7 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D7
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        movlw   LED_D7_ON   ; Write '1' for D7 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D7
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        bsf     STATUS, RP0 ; Bank 1 selected
        movlw   TRISA_D01       ; Configure LEDs D0 and D1 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D1_ON   ; Write '1' for D1 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D1
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY
        bsf     STATUS, RP0 ; Bank 1 selected
        movlw   TRISA_D67       ; Configure LEDs D6 and D7 in TRISA
        movwf   TRISA
        bcf     STATUS, RP0 ; Bank 0 selected
        movlw   LED_D7_ON   ; Write '1' for D7 into Working Register
        movwf   PORTA       ; Send '1' through PORTA to light up LED D7
        call    DELAY
        clrf    PORTA       ; Clear PORTA
        call    DELAY

        goto   START    ; loop again - Loop forever - blink continuously
DELAY
LOOP1
        decfsz   COUNT1,1   ; Decrement COUNT1 and skip next instruction if zero
        goto     LOOP1      ; else loop back to LOOP1
        decfsz   COUNT2,1   ; Decrement COUNT2 and skip next instruction if zero
        goto     LOOP1      ; else loop back to LOOP1
        movlw    0xff       ; Reload the second counter for the next iteration
        movwf    COUNT2
        return
end