hi!
  I am using the 16F877, 4MHz processor.
  I have this problem with getting the recive(UART) to work. I have =
tried too get both the interrupt and polling to work. It used to work so =
I guess I just missed something somewhere. when I run the program it =
stopps just after GET_DATA after all the INIT:s. it can't get passed the =
RCIF flag. this should work without the interrupt(INTCON) set I think. =
nothing happens to the interrupt as well. it never goes to the interrupt =
vector.
  I have made macros for the BANK0 and BANK1 and they work. when I =
simulate the program with mplab all the reg. works. I am just using =
GET_DATA now but want to use interrupts when I get it to work. at the =
moment nothing happens. there is no problem to send data(TXD) only to =
recive.

  I have attached the hole program if anyone could be so kind to have a =
look at it.
  thanks. this is just a part of it here in the mail.=20

  /nabil



  ;***** VARIABLE DEFINITIONS
  w_temp         EQU     0x70        ; variable used for context saving=20
  status_temp   EQU     0x71        ; variable used for context saving
  S_OUT  EQU 0X72
  TEST2  EQU 0X74
  TEST3  EQU 0X75
  S_IN  EQU 0X76
  S_IN_CHECK EQU 0X77



   ORG     0x000             ; processor reset vector
   CLRF    PCLATH            ; ensure page bits are cleared
   GOTO    MAIN              ; go to beginning of program


   ORG     0x004             ; interrupt vector location
   MOVWF   w_temp            ; save off current W register contents
   MOVF STATUS,w          ; move status register into W register
   MOVWF status_temp       ; save off contents of STATUS register


  ; isr code can go here or be located as a call subroutine elsewhere
  =20
   BSF PORTB,4=20
  =20
   MOVF status_temp,w     ; retrieve copy of STATUS register
   MOVWF STATUS            ; restore pre-isr STATUS register contents
   SWAPF   w_temp,f
   SWAPF   w_temp,w          ; restore pre-isr W register contents
  =20
   RETFIE                    ; return from interrupt


  ;****** sends 1 byte to TxD. *********

  SEND_DATA    =20
         MOVF    S_OUT,W    =20
         BANK0         =20
         MOVWF   TXREG           ;txreg fylls med s_out.
         BANK1 =20
  NOT       =20
        BTFSS TXSTA,TRMT ;tests to se if data sent
        GOTO NOT  ;if not empety go back and try agsain.
        BANK0 =20
       =20
        RETURN=20
      =20
  ;******* recives 1 byte from RxD. *****

  GET_DATA
      =20
           BANK0
           BSF PORTB,7
  EMPTY
          BTFSS   PIR1, RCIF
          GOTO    EMPTY
          BSF PORTB,6=20
          BANK0
          MOVF RCREG,W
          MOVWF S_IN
      =20
          RETURN


  ;********** Port setup ****************    =20

  INIT_PORT
  =20
        BANK0
        CLRF PORTC               =20
        CLRF    PORTB=20
        BANK1
        MOVLW   H'80'           =20
        MOVWF   TRISC           ;bit 7(rx), is input. all the rest is =
output.
        MOVLW   H'00'     =20
        MOVWF TRISB  ;all id outputs.
        BANK0
  =20
        RETURN

  INIT_INTERRUPT
  =20
       ;CLRF PCLATH
       MOVLW B'11000000' ;move h'00' to clear all the interrupts.
       MOVWF INTCON  ;SET ALL INTERRUPTS
  =20
       RETURN

  ;********** serie port init ***********   =20

  INIT_SERIE
      =20
      BANK1
      MOVLW  0X19            ;4MHz/9600=20
      MOVWF    SPBRG         =20
     =20
      BCF TXSTA, SYNC
      BSF   TXSTA, BRGH     ;sets the high speed transmit.    =20
      BSF PIE1, RCIE ;sets the recive interrupt ready.=20
      BSF TXSTA, CSRC ;too test the transfer
      BCF TXSTA, TRMT
      BANK0
      BSF  RCSTA, SPEN    =20
      BSF     RCSTA, CREN     ;needed to recive data.
      BANK1    =20
      BSF     TXSTA, TXEN     ;make the txreg ready to send data
      BANK0

      RETURN

  ;*************************************
  MAIN

       CALL  INIT_PORT ;sets up all the i/o ports.
       CALL INIT_SERIE ;starts the serie connection.
       CALL INIT_INTERRUPT ;starts the interrupt.
  =20
       MOVLW H'30'
       MOVWF S_OUT
       CALL  SEND_DATA
  START=20
      CALL GET_DATA
      GOTO START

  END                       ; directive 'end of program'

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