Help needed on simple SCI program... why don't I get the same result back

christophe2399 · ‎2003-12-31

Posted on December 31, 2002 at 10:01

christophe2399 · ‎2002-12-26

Posted on December 26, 2002 at 19:50

code :

.include $SetupFileName

segment 'Ram0'

.MB DS.B 1 ; variabele byte op adres 80h

segment 'Rom' ; Code segment - Address defined in device file (.str)

; Main Code here

.main

call ontvang

call wachten

call verstuur

call wachten

jra main

.ontvang

bset SCICR2,#2 ; RDI begint te zoeken naar een startbit

wacht btjf SCISR,#5,wacht ; Wait for reception of a new byte

ld A,SCISR

ld A, SCIDR

ld MB,A

ret ; RDRF = hoog als 1 byte ontvangen is

.wachten

ld X,#255

w2 ld A,#255

w1 dec A

jrne w1

dec X

jrne w2

ret

.verstuur

bset SCICR2,#3

ld A,SCISR

ld A,#$80

ld SCIDR,A

wacht1 btjf SCISR,#7,wacht1

ld A,SCISR

ld A,MB

ld SCIDR,A

wacht2 btjf SCISR,#7,wacht2

ret

.include $VectorFileName ; Interrupt and Vector file (.stv) included here

end

This program first accepts 1 byte from the PC and than sends back #80 and the received byte MB to the PC...

The problem is that do not get the value back that I've sent to the MCU.

What is wrong?

thanks

chill@mine.be

stephanie · ‎2003-12-31

Posted on December 31, 2002 at 10:01

Hi,

the btjf SCISR,#x,wacht already performs an access to SCISR. You don't need to read it once again after the btjf, maybe this can disturb the communication. It's better to put the SCI initialisation in a dedicated routine (TE,RE can be set at a time cause SCI is full duplex).

I attach a file written in C but containing in-line assembly. Hoping it will help!

[ This message was edited by: stef on 31-12-2002 14:32 ]

________________

Attachments :

Sci.zip : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0As&d=%2Fa%2F0X0000000bW3%2F24XX0rFzE81VMmOx6ePTmPyV9ar9N14pfx0VK6fvWD8&asPdf=false