I am trying to talk to a pc with a 16F877 USART.  Nowhere in the docs
does it say whether I need a serial interface chip or not, so I stuck a
meter on the output of pins <26:25>, and I didn't see any negative
voltage, so I am assuming I do need a chip (although I tried it without,
just in case).  The circuit works fine with other code loaded in it, and
o-scopes ok too (not that I know what I'm doing with it, but hey :-)
Circuit has a 10Mhz x-tal.  I tried connecting it to a laptop and a pc.
Also tried various combinations of CTS/RTS & DTR/DSR with no luck.  The
laptop echoes perfectly when TX is tied to RX.  Anyway, the circuit was
producing gibberish on the screen (wired as 3-wire, no flow control), so
it seemed like I had it wired properly and had a baud rate problem, so I
tried the code below with different SPBRG and baudrate=0 and 1 with no
luck. I'm just using hyperterminal.  Then I noticed that I forgot to
connect pin 15 of the MAX232A to ground (duhhhh!), so I did, and it
won't utter a bit.  That ground also makes the OSC all fuzzy on the
scope.  It still has +/-10v on pins 2 and 6, tho.  I used .1uf caps as
indicated on page 17 of the datasheet.  (Those are just dumb.  Will use
a Dallas next time!)  Help!

 list p=16F877, R=DEC
 #include <c:\pic\mpasm\p16F877.inc>

; Registers

i equ 0x0C
j equ 0x0D

 __CONFIG _CP_OFF & _WDT_OFF & _XT_OSC & _PWRTE_ON

 org 0x0000

; Constants

        CONSTANT LF =   d'10'   ; Line Feed
        CONSTANT CR =   d'13'   ; Carriage Return

; Initialize ports
 clrf PORTA   ; Set PORTA output latch to 0 (optional)
 clrf PORTB   ; Set PORTB output latch to 0
 clrf PORTC   ; Set PORTC output latch to 0
 clrf PORTD   ; Set PORTC output latch to 0
 clrf PORTE   ; Set PORTC output latch to 0
 bsf STATUS,RP0  ; Switch to Bank1
 movlw B'11000000'  ; Set PORTC 7,6 to TRI-state for RX/TX
 movwf TRISC   ; Set PORTC to all outputs & TRI-S for RX,TX
 bcf STATUS,RP0  ; Switch back to Bank0
; Initialize USART Transmitter
 movlw B'10000000'  ; Select: Port C serial ports (not I/O), RX disabled

 movwf RCSTA
 bsf STATUS, RP0  ; Switch to Bank1
 movlw d'32'   ; 19,200bps for 10Mhz x-tal
 movwf SPBRG   ;
 movlw B'00100100'  ; Select Asynchronous, 8bit, high baud rate, TX
enabled serial port
 movwf TXSTA   ;
 bcf STATUS, RP0  ; Switch to Bank0

;TEMP                      ; also tried
;movlw 'X'                 ; this, instead
;movwf TXREG        ; of the table
;goto TEMP              ; stuff below

start clrf i
loop movf i,w
 incf i
 call  HelloTable
 movwf j
 movf j
 btfsc STATUS,Z
  goto start
 movwf TXREG   ; Move w to TX register
 goto loop

HelloTable
 addwf PCL
 retlw 'H'
 retlw 'e'
 retlw 'l'
 retlw 'l'
 retlw 'o'
 retlw CR
 retlw LF
 retlw 0

 end