Hey everyOne!

I'm having problems to decode the FM0 [
http://www.grantronics.com.au/serialformats.html ] data , the data rate
is 40 kbps and my atmega16 is using 16 Mhz clock.


MCU = atmega16
CPUclk = 16 Mhz
Prescaler Value = 8
Datarate = 40 kbps
Bit rate = 25 micro second

I have tried to use external interrupt pin for one edge and as well as
for both edges (Inverting the interrupt sense) but no luck so far. The
error rate is more than 50% ;-).

Any good pointers?

Regards,
ali

What is the best way to do this.

1) Catch either edge (falling , rising).
2) Catch every edge.

Your answer?

Tahnks

Ali wrote:
What is the best way to do what? Your question? See 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/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

Ali wrote:

This is pretty much the old floppy single-density data decoding
problem.

If we convert the incoming data stream into a stream of transition
pulses, there are two interleaved pulse trains: clocks at each
bit cell boundary and data at the center of each bit cell. You
have to identify the streams in some way. The circuit used with
disk recording was called data separator, although its main task
is to identify the clock edges.

The customary way in FM disk recording was a special clock/data
pattern called an address mark, which was detected by the decoder.
This was also used to detect the byte boundaries.

A simple way of detecting the clock was a timer of 3/4 bit cell
and which was started by the incoming edge. It will sync to the
clock edges after the first missing data pulse, but it assumes
that the data stream is error-free.

For more robust clock detection, phase-locked loops (PLL) are used.

HTH

--

Tauno Voipio
tauno voipio (at) iki fi

CBFalconer wrote:
every one could understand;-)

Addition to Tauno Voipio post:

Yeah you are right and I'm also using PLL in my design but the
problem is with RF part , yeah my audio data stream is in form of radio
frequency . A hell noise and all the time signal is distorted.

"Ali" <abdulrazaq@gmail.com> wrote in message
news:1145413723.102683.200110@g10g2000cwb.googlegr oups.com...
What original post? The threat started with "Re: FM0 (bi-phase space)
decoding!".

Peter

Peter wrote:

Peter


Hmm , tahts why i'm saying to look at OP rather thread with 'Re';-)

"Ali" <abdulrazaq@gmail.com> wrote in message
news:1145437241.247185.64990@e56g2000cwe.googlegro ups.com...
You can't say look at such-and-such a message because you can't guarantee
that everyone recieves all the messages - and in my case I didn't. As a
result your message reads like one side of a telephone conversation -
perhaps I can figure out what some of it means but it's real hard work.

Peter

Well i use google's interface for UseNet and its simple to view whole
thread at a glance. Not sure how other interfaces present useNet
threads anyhow I think we should be concentrating on problem nOw ;-)

Any good pointers for bi-phase decoding design?
Regards,
ali

Ali wrote:
As you have already been told, Google's interface is badly broken. It
is not a proper newsreader, nor a suitable interface for posting - it's
merely an interface for searching the archives. If possible, you should
use a proper newsreader and a proper Usenet feed - failing that, you
should use Google's interface properly.

"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/>
Also see <http://www.safalra.com/special/googlegroupsreply/>


If you want to capture both edges, it might be easier to route the
signal to two interrupt pins and configure one for rising edges, and the
other for falling edges. Timer captures can also be useful here.

"Ali" <abdulrazaq@gmail.com> schreef in bericht
news:1145440040.735700.21020@i40g2000cwc.googlegro ups.com...
I think you should be concentrating on getting a proper
newsreader and quit using that broken Google interface to
usenet.

Because it is possible to post correctly from Google, new
Google posters may get the benefit of the doubt, but their
credit quickly evaporates, and certainly when you start
lecturing about the whereabouts of the original post.

And to confirm that, *PLONK* !

--
Thanks, Frank.
(remove 'q' and '.invalid' when replying by email)

In article <1145440040.735700.21020@i40g2000cwc.googlegroups. com>, Ali
<abdulrazaq@gmail.com> writes
That is obvious. It is broken and ONLY works with google users. The rest
of us (that is the vast majority of Usenet users) do not.

Then you are in a MINORITY. You are also breaking the conditions of use
of Usenet.

the problem is your incorrect use of Usenet.

If some one joins a conversation and is very rude people tend not to
help them.


--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
/\/\/ chris@phaedsys.org www.phaedsys.org \/\/\
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Well that's totally personal choice and yeah its true when it comes
to broken links , the reason I use web interface is freedom from
applications (newsreaders , feedbacks etc. ).

David wrote:
the
other for falling edges. Timer captures can also be useful here.

Thanks David sounds interesting, I have tried to capture both edges on
the same interrupt pin and now i'll try to capture both edges with tow
pins. What kind of software filter I can design to eliminate the noise
factor?


Frank Bemelman wrote:
And to confirm that, *PLONK* !


Hmm interesting , ain't gonna confirm anything let the readers decide
;-)


ali

Ali wrote:
Please don't mix up quotations from different posts in different
sub-threads unless it is actually relevant. If you want to use a broken
interface because you have some masochistic aversion to using
appropriate applications, that's your choice - but don't expect others
to go out of their way to help you when you don't have the common
decency to follow Usenet standards, and when you ignore advice pointing
you in the right direction.

David

Thanks for your advice.

In article <1145446014.845199.9320@i39g2000cwa.googlegroups.c om>, Ali
<abdulrazaq@gmail.com> writes
Top posting too.... Are yo deliberately trying to piss people off?

Do you realise how stupid your last comment was... "freedom from
applications" like news readers.... you are using a web browser That is
an application and it is less secure than a news reader.

You clearly have little knowledge of what you are doing.


You he is right. You can set up the goolge reader to conform to the
rules if not you ain't going to get much help
--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
/\/\/ chris@phaedsys.org www.phaedsys.org \/\/\
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

In article <1145449379.967096.125030@g10g2000cwb.googlegroups .com>, Ali
<abdulrazaq@gmail.com> writes
the google interface and you haven't bothered.

Most of the people how you are arguing with could have answered your
technical question. they haven't due to your attitude.

If you had been polite and set up the goolge interface properly you
would have had your answers already.
--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
/\/\/ chris@phaedsys.org www.phaedsys.org \/\/\
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Ali wrote:
There is little point in thanking me for advice, when you ignore it
completely. Let's try this one more time, before I join the ranks of
posters who have killfiled you:

"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/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

What's the gripe with the google reply feature? You aren't supposed to
reply to a message in the middle of a thread? The preferred reply
method is to only add replies at the end of the thread? (This seems
moot if the thread is sorted by date in the reader)

"BobG" <bobgardner@aol.com> wrote in message
news:1145467634.879724.159030@v46g2000cwv.googlegr oups.com...
The gripe is lack of context within a single message.

For example: here, I've quoted (and attributed) the bit I'm responding to.

This isn't just pedantry: it's simple netiquette.

Steve
http://www.fivetrees.com