PIC con LCD 4bit

Para tener mas  pines libres de salida de un pic es preferible usar la interfaz al LCD con 4 bits, en este ejemplo usamos el puerto B con los 4 bits mas altos(RB4-RB7) conectados a los pines mas altos (D4-D7)del  LCD, de igual forma pongo todo el programa completo sin uso librerias.
;*******************************************

; 4 BIT LCD CON PIC16F84A
; RB7-RB4 = DB7-DB4 ; E=RB3 ; RW= RB2 ; RS=RB1
;*******************************************
list p=PIC16F84A
include "p16f84a.inc"
BIT_E          EQU 3
BIT_RW      EQU 2
BIT_RS       EQU 1
TEMP          EQU 0x020
reg1             EQU 0x021
reg2             EQU 0x022

org 0h
goto START

INITPIC                                  ;Configuracion de puertos
            bsf STATUS,RP0        ; vamos bank 1
           movlw b'00000000'
           movwf TRISB              ;puerto b salida
           bcf STATUS,RP0        ; vamos bank 0
          clrf PORTB
          return

INITLCD                                 ;inicializar LCD
              MOVLW 0xFE
              CALL retardo1
              MOVLW B'00111000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              MOVLW 0x0A               ;retardo 5ms
              CALL retardo1
              MOVLW B'00111000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              MOVLW 0x02
              CALL retardo1
              MOVLW B'00111000'
              MOVWF PORTB
              BCF PORTB,BIT_E
             CALL LCDBUSY
              MOVLW B'00101000'
              MOVWF PORTB
              BCF PORTB,BIT_E
             CALL LCDBUSY
             MOVLW B'00101000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              MOVLW B'10001000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              CALL LCDBUSY
              MOVLW B'00001000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              MOVLW B'11111000'
              MOVWF PORTB
             BCF PORTB,BIT_E
              CALL LCDBUSY
              MOVLW B'00001000'
              MOVWF PORTB
              BCF PORTB,BIT_E
              MOVLW B'00011000'
              MOVWF PORTB
             BCF PORTB,BIT_E
             CALL LCDBUSY
             MOVLW B'00001000'
             MOVWF PORTB
             BCF PORTB,BIT_E
             MOVLW B'01101000'
             MOVWF PORTB
             BCF PORTB,BIT_E
             RETURN
LCDBUSY
             BSF STATUS,RP0
             MOVLW B'11110000'
             MOVWF TRISB
             BCF STATUS,RP0
             BSF PORTB,BIT_RW
             BCF PORTB,BIT_RS
             BSF PORTB,BIT_E
             MOVF PORTB,W
            BCF PORTB,BIT_E
            BSF PORTB,BIT_RW
            BCF PORTB,BIT_RS
            BSF PORTB,BIT_E
            NOP
            BCF PORTB,BIT_E
            ANDLW 0x80
            BTFSS STATUS,Z
           GOTO LCDBUSY
            BCF PORTB,BIT_RW
            BSF STATUS,RP0
            MOVLW 0x000
            MOVWF TRISB
            BCF STATUS,RP0
             RETURN

LINE2       
          MOVLW B'11001000'
          MOVWF PORTB
          BCF PORTB,BIT_E
          MOVLW B'00001000'
          MOVWF PORTB
          BCF PORTB,BIT_E
          RETURN

LCDWRITE
           MOVWF TEMP
           CALL LCDBUSY
           MOVF TEMP,W
            ANDLW B'11110000'
            IORLW B'00001010'
            MOVWF PORTB
            BCF PORTB,BIT_E
            SWAPF TEMP,W
           ANDLW B'11110000'
            IORLW B'00001010'
            MOVWF PORTB
           BCF PORTB,BIT_E
           RETURN
DEMORA                    ;retardo 500uS con xt 4MHz

            MOVLW D'165'
            MOVWF reg1
DEMORA1
            DECFSZ reg1, F
            GOTO DEMORA1
            RETURN
retardo1
            MOVLW D'255'
            MOVWF reg2
DEMORA2
            CALL DEMORA
            DECFSZ reg2, F
            GOTO DEMORA2
            RETURN

START
CALL INITPIC               ;inicializar PIC
CALL INITLCD              ;inicializar LCD
inicio
               call retardo1
               MOVLW D'80'              ;P
               CALL LCDWRITE
               MOVLW D'82'              ;R
               CALL LCDWRITE
               MOVLW D'79'              ;O
               CALL LCDWRITE
               MOVLW D'89'              ;Y
               CALL LCDWRITE
               MOVLW D'69'              ;E
              CALL LCDWRITE
              MOVLW D'67'               ;C
              CALL LCDWRITE
              MOVLW D'84'               ;T
              CALL LCDWRITE
              MOVLW D'79'               ;O
              CALL LCDWRITE
              MOVLW D'83'              ;S
             CALL LCDWRITE
              MOVLW D'32'              ;espacio en blanco
              CALL LCDWRITE
               MOVLW D'50'             ;2
               CALL LCDWRITE
               MOVLW D'48'             ;0
               CALL LCDWRITE
               MOVLW D'49'             ;1
               CALL LCDWRITE
              MOVLW D'49'              ;1
              CALL LCDWRITE
              MOVLW D'32'              ;espacio en blanco
              CALL LCDWRITE
              SLEEP
               END

El archivo HeX. probado y comprobado lo pueden bajar de este enlace:
http://www.4shared.com/file/SBnq3pu0/lcd4bit.html