Hi,

when using 16F84, the user RAM begins at 0Ch, rather than at 8. Correct
your ORG statement! And I guess, the carry must be inverted before sending
due to the MAX232.

Regards,
Imre


On Fri, 22 Oct 1999, Aart Arenoe wrote:

> Hello,
>
> i want to establesh a connection between the 16F84 and the RS232 port at my co
mputer. The code i use is from the application notes from techtools Chapter 3, b
ut they are talking about the 16c54 in the example is there a difference for thi
s usage?
> Also i'm using a the max232 as shown in the example, but all there is is rubis
h at my screen (good old term95). Is there somebody who did manage to get the pi
c talking to the RS232? I'm using the CVASM16 assambler. It's not the computer c
ause the Universal Infrared Remotecontrol works great on the same port.
> Here the code..thanks for your reaction in advance!
> (i'm using a 4mc christal)
> Aart.
>
>
> PROGRAM: XMIT232.SRC
> ; Taken from Parallax PIC Applicaton Note: Sending RS-232 Serial Data
> ; Written     July 15, 1993
> ; Revised February 24, 1996
>
> ; This program transmits a string of serial data. The baud rate is determined
> ; by the value of the constant bit_K and the clock speed of the PIC. See the
> ; table in the application note (above) for values of bit_K. For example, with
> ; the clock running at 4 MHz and a desired transmitting rate of 4800 baud,
> ; make bit_K 50.
>
> ; >>> Remember to change device info if programming a different PIC! <<<
> ; Do not use RC devices. Their clock speed is not sufficiently accurate
> ; or stable enough for serial communication.
>
> device pic16f84,xt_osc,wdt_off,protect_off   ; changed the procesor type from
16c54
>                                                                ; into 16f84
>
> bit_K  = 24                                               ;24 for 9600-baud op
eration @ 4 MHz
> serial_out = ra.2                                        ;Output naar pin 1 va
n IC
> org     8                                                    ;Start of availab
le RAM
> delay_cntr ds 1                                         ;Counter for serial de
lay routines
> bit_cntr ds 1                                              ;Number of transmit
ted bits
> msg_cntr ds 1                                           ;Offset in string
> xmt_byte ds 1                                           ;The transmitted byte
> org     0                                                     ;Start of code s
pace (ROM)
> jmp begin                                                  ;Start Programma.
>
> begin  mov !ra, #00000000b                        ;Set port to output.
> mov msg_cntr, #0                                      ;Message string has nine
 characters;
>                                                                 ;0 through 8.
> :again  mov bit_cntr,#8                               ;Eight bits in a byte.
>            mov w,msg_cntr                             ;Point to position in th
e string.
>            call string                                      ;Get the next char
acter from string.
>            mov xmt_byte,w                             ;Put character into the
transmit byte.
>
>            clrb serial_out                                 ;Change to setb ser
ial_out for direct
>                                                                 ;connection.
>
>            call bit_delay ;Start bit.
>
> :xmit    rr xmt_byte                                    ;Rotate right moves da
ta bits into
>                                                                 ;carry, starti
ng with bit 0.
>
>            movb serial_out,c                           ;Change to movb serial_
out,/c for
>                                                                ;direct connect
ion.
>
>            call bit_delay                                 ;Data bit.
>            djnz bit_cntr,:xmit                          ;Not eight bits yet? S
end next data bit
>
>            setb serial_out                               ;Change to clrb seria
l_out for direct
>                                                                ;connection
>
>           call bit_delay                                   ;Stop bit.
>           inc msg_cntr                                   ;Add one to the strin
g pointer.
>
>           cjbe msg_cntr,#8,:again
>                                                                 ;More characte
rs to send? Go to the top
>
> :endless jmp :endless                                ;Endless loop. Reset cont
roller to run
>                                                                 ;program.
>
> ; To change the baud rate, substitute a new value for bit_K at the beginning o
f
> ; this program.
>
>          bit_delay mov delay_cntr,#bit_K
> :loop  nop
>          djnz delay_cntr, :loop
>          ret
>
>          string  jmp pc+w                              ;String consisting of "
Parallax"
>                                                                ;followed by a
linefeed.
>
>          retw 'P','a','r','a','l','l','a','x',10
>
>