68HC11 PORT B

This is top posting.

In article <1138127807.972537.169750@o13g2000cwo.googlegroups.com>, 
conphiloso@hotmail.com says...
> Hi,
> 
> I do not know how not to top post. please advice. I tried both syntaxs
> the result is same.
> 

This is where you should respond.
If you need to snip old junk to keep the post manageable that's fine.

Anyway, I'm sure your little code snippet is not the entire file you are 
assembling, or is it?  You should have reset vectors defined and the 
like.  

Your complete file should be a little more in depth.
For example, this assembly routine to alter the CONFIG register :

; THE 'HC11 MUST BE IN ONE OF THE SPECIAL MODES TO PROG. CONFIG
; CHANGES WON'T TAKE UNTIL RESET
; ASSUMES AN HC11Ax WITH AN 8MHZ OSC (2MHZ ECLOCK)

     ORG     $A000

EX31A   LDS     #$00FF          ;set stack ptr
        LDAA    #$00            ;turn off EEPROM protect
        STAA    $1035           ;write it
        LDAA    #$00            ;preset porta
        STAA    $1000           ;write it
        LDAA    #$0F            ;set porta
        STAA    $1001           ;write to ddr
        BSR     DLY10           ;delay 10 ms
        LDAA    #$0A            ;get desired config value (change if 
needed)
                                ; 0a = COP,NOEEPROM
        CMPA    $103F           ;compare it to the actual value
        BEQ     NOWOK           ;if it is OK goto nowok
                                ;else do this
        LDAB    #$16
        STAB    $103B           ;SETUP PPROG REGISTER FOR BYTE ERASE
        STAA    $103F           ;DO ANY WRITE TO THE REGISTER
        INCB
        STAB    $103B           ;TURN ON THE PROG VOLTAGE
        BSR     DLY10           ;DELAY 10MS
        CLR     $103B           ; TURN OFF THE PROG VOLTAGE

        LDAB    #$02
        STAB    $103B           ;SETUP TO WRITE THE DATA
        STAA    $103F           ; NOW WRITE THE ACTUAL DATA
        INCB
        STAB    $103B           ; TURN ON THE PROG VOLTAGE
        BSR     DLY10           ; WAIT AGAIN
        CLR     $103B           ; TURN OFF EVERYTHING

PROGED  LDAA    #$08            ; FLIP A PORT BIT
        STAA    $1000           ; I USE THIS BIT TO TOGGLE AN LED
        BRA     PROGED          ; WAIT FOR RESET

NOWOK   LDAA    #$04            ;IF CONFIG VALUE OK FLIP DIFFERENT BIT
        STAA    $1000
        BRA     NOWOK           ; WAIT FOREVER

DLY10   PSHX                    ; HARD CODED 10MS DELAY BASED ON ABOVE 
ASSUMPTIONS
        LDX     #$1A0C
DLOOP   DEX
        BNE     DLOOP
        PULX
        RTS

        ORG     $BFFE
RESET   FDB     $A000

john wrote:
> Hi,
> 
> I am having problems with  the port B. Its an output port and I am
> writing the whole port. My code is as follows
> 
> ORG 2000
> LDAA  $# FF
> STAA  $1004
> 
> Now, if I write 00 hex  or FF to theport. The port is always floating.
> I tried pull ups and pull downs but no difference. Please advice.
> Thanks

A couple of questions:
Which 68HC11 variant are you using?
Are you using it in single chip or expanded mode?

The only HC11 docs I have, show port B as an output only port and don't 
show any way to disable the output transistors. Is your port truly 
floating or is it just not responding to the input register? The docs I 
have are for an A8, E2 or E9 part. If the port really is floating and 
the part is powered up and grounded properly, it is possible that the 
port is cooked.

If you are using the HC11 in normal, single chip mode, the MODB pin 
should be tied to +5v through a resistor and the MODA pin tied to 
ground. If the MODA pin is not grounded, the data register cannot be 
written by the data bus, it's stuck as the high order address bus. If 
you are using an expanded mode with the port replacement chip, I would 
suspect that the port replacement chip is not set up right or is cooked.

Good Luck,
Bob

john wrote:
> 
> I do not know how not to top post. please advice. I tried both
> syntaxs the result is same.

The following will explain it:

http://www.caliburn.nl/topposting.html
http://www.netmeister.org/news/learn2quote.html
http://www.catb.org/~esr/faqs/smart-questions.html
http://www.greenend.org.uk/rjk/2000/06/14/quoting.html
http://www.i-hate-computers.demon.co.uk/
http://web.ukonline.co.uk/g.mccaughan/g/remarks/uquote.html

Also, include adequate context in your messages, even if using
googles broken usenet interface.  All articles should stand by
themselves.  See instructions and reference in my sig below.

-- 
"If you want to post a followup via groups.google.com, don't use
 the broken "Reply" link at the bottom of the article.  Click on 
 "show options" at the top of the article, then click on the 
 "Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>

"MetalHead" <WanderingMetalHead@DUMPSPAM.yahoo.com> wrote in message
news:huzBf.1711$wk5.999@news02.roc.ny...
> john wrote:
> > Hi,
> >
> > I am having problems with  the port B. Its an output port and I am
> > writing the whole port. My code is as follows
> >
> > ORG 2000
> > LDAA  $# FF
> > STAA  $1004
> >
> > Now, if I write 00 hex  or FF to theport. The port is always floating.
> > I tried pull ups and pull downs but no difference. Please advice.
> > Thanks
>
> A couple of questions:
> Which 68HC11 variant are you using?
> Are you using it in single chip or expanded mode?
>
> The only HC11 docs I have, show port B as an output only port and don't
> show any way to disable the output transistors.  up right or is cooked.
>
> Good Luck,
> Bob

Hi John,

I have to agree with Bob, we need to know what variation of the HC11 you are
using and the mode it's operating in.

Also are you sure you really want your program to start at 2000 decimal (Or
7Dh). All the memory maps I've checked don't appear to have anything useable
for a programmer at this location.

Hope this helps,
James