Please Recommend Wireless Protocol and How-To/Tutorial

I am a student in an embedded systems design class.  I am planning a
project where I'll get two 8051-microcontroller-based development
boards with 433 MHz FM transceivers to talk to each other.  Each
development board will be connected via RS-232 to a computer running
terminal software.  My initial goal is to be able to send some
keystrokes back and forth between the two systems.

The real challenge of the project is in developing my own wireless
protocol to handle packetization, start and stop codes, error
detection and correction, line coding, and perhaps collision handling.
 I am looking for a good tutorial on how to go about such a task--i.e.
what options are available and guidelines for implementing them. 
Something on the web or a book would both be good. I was wondering if
you might be able to make a recommendation.

Additionally, if you would please recommend any existing protocols
that would be sufficient for my application, this would be very
helpful because: a) I can use the existing protocol as a reference
when developing my own and b) If it turns out to be too difficult to
develop my own, I can switch my goal to implementing the existing
protocol.

I would be very grateful for any assistance that you might be able to
provide.  Thanks so much for your help.

usenet@pobox.com (usenet@pobox.com) writes:

> I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.

Dude, do your own research :-)

I ordered these from www.futurlec.com:

 http://www.futurlec.com/Radio.shtml

Good stuff for hobby projects.

 S.

<usenet@pobox.com> wrote in message
news:8ded0ef5.0411022017.542f84a7@posting.google.com...
> I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.
>
> The real challenge of the project is in developing my own wireless
> protocol to handle packetization, start and stop codes, error
> detection and correction, line coding, and perhaps collision handling.
>  I am looking for a good tutorial on how to go about such a task--i.e.
> what options are available and guidelines for implementing them.
> Something on the web or a book would both be good. I was wondering if
> you might be able to make a recommendation.
>
> Additionally, if you would please recommend any existing protocols
> that would be sufficient for my application, this would be very
> helpful because: a) I can use the existing protocol as a reference
> when developing my own and b) If it turns out to be too difficult to
> develop my own, I can switch my goal to implementing the existing
> protocol.
>
> I would be very grateful for any assistance that you might be able to
> provide.  Thanks so much for your help.

The two that amateurs use are x25 and tcpip. The ham radio implemetation of
x25 (ax25) is what is used in packet radio. It is well documented in all
communication layers. Tcpip is well documented in the internet rfc and other
docs, though I don't remember seeing any timing specs like are included in
x25.

usenet@pobox.com wrote:
> I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.
> 
> The real challenge of the project is in developing my own wireless
> protocol to handle packetization, start and stop codes, error
> detection and correction, line coding, and perhaps collision handling.
>  I am looking for a good tutorial on how to go about such a task--i.e.
> what options are available and guidelines for implementing them. 
> Something on the web or a book would both be good. I was wondering if
> you might be able to make a recommendation.
> 
> Additionally, if you would please recommend any existing protocols
> that would be sufficient for my application, this would be very
> helpful because: a) I can use the existing protocol as a reference
> when developing my own and b) If it turns out to be too difficult to
> develop my own, I can switch my goal to implementing the existing
> protocol.
> 
> I would be very grateful for any assistance that you might be able to
> provide.  Thanks so much for your help.

Do a google search on "serial transfer protocol". You will get about
500,000 hits.

Initially look for the standard terminal communication protocol. That
already has some form of packetization, start and stop codes, error
detection and correction. It's relatively simple so you can expand from
there.

-- 
Martin E. Meserve - K7MEM
http://www.k7mem.150m.com

<usenet@pobox.com> wrote in message
news:8ded0ef5.0411022017.542f84a7@posting.google.com...
> I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.
>
> The real challenge of the project is in developing my own wireless
> protocol to handle packetization, start and stop codes, error
> detection and correction, line coding, and perhaps collision handling.
>  I am looking for a good tutorial on how to go about such a task--i.e.
> what options are available and guidelines for implementing them.
> Something on the web or a book would both be good. I was wondering if
> you might be able to make a recommendation.
>
> Additionally, if you would please recommend any existing protocols
> that would be sufficient for my application, this would be very
> helpful because: a) I can use the existing protocol as a reference
> when developing my own and b) If it turns out to be too difficult to
> develop my own, I can switch my goal to implementing the existing
> protocol.
>
> I would be very grateful for any assistance that you might be able to
> provide.  Thanks so much for your help.

Didn't the supplier of the transceivers give you any application
guidelines?

Rufus

"Rufus V. Smith" <nospam@nospam.com> wrote in message news:<B58id.1994$VI3.453@sam.nntpserver.com>...
> <usenet@pobox.com> wrote in message
> news:8ded0ef5.0411022017.542f84a7@posting.google.com...
> > I am a student in an embedded systems design class.  I am planning a
> > project where I'll get two 8051-microcontroller-based development
> > boards with 433 MHz FM transceivers to talk to each other.  Each
> > development board will be connected via RS-232 to a computer running
> > terminal software.  My initial goal is to be able to send some
> > keystrokes back and forth between the two systems.
> >
> > The real challenge of the project is in developing my own wireless
> > protocol to handle packetization, start and stop codes, error
> > detection and correction, line coding, and perhaps collision handling.
> >  I am looking for a good tutorial on how to go about such a task--i.e.
> > what options are available and guidelines for implementing them.
> > Something on the web or a book would both be good. I was wondering if
> > you might be able to make a recommendation.
> >
> > Additionally, if you would please recommend any existing protocols
> > that would be sufficient for my application, this would be very
> > helpful because: a) I can use the existing protocol as a reference
> > when developing my own and b) If it turns out to be too difficult to
> > develop my own, I can switch my goal to implementing the existing
> > protocol.
> >
> > I would be very grateful for any assistance that you might be able to
> > provide.  Thanks so much for your help.
> 
> Didn't the supplier of the transceivers give you any application
> guidelines?
> 
> Rufus

Unfortunately, they didn't.

I'd like to thank all of you who have replied to this post for all of
your assistance.  I have a strong desire to learn about wireless, but
unfortunately I took on a risk in doing so in that I've ventured
outside of the realm of my Professor's expertise and it's up to me to
figure it all out on my own.  I am really hoping that the resources
you have suggested will be sufficient to enable me to get the job
done.  If anyone else has anything to contribute, I would really
appreciate it.  Thanks to you all...

<usenet@pobox.com> wrote in message 
news:8ded0ef5.0411022017.542f84a7@posting.google.com...
>I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.
>
> The real challenge of the project is in developing my own wireless
> protocol to handle packetization, start and stop codes, error
> detection and correction, line coding, and perhaps collision handling.
> I am looking for a good tutorial on how to go about such a task--i.e.
> what options are available and guidelines for implementing them.
> Something on the web or a book would both be good. I was wondering if
> you might be able to make a recommendation.
>
> Additionally, if you would please recommend any existing protocols
> that would be sufficient for my application, this would be very
> helpful because: a) I can use the existing protocol as a reference
> when developing my own and b) If it turns out to be too difficult to
> develop my own, I can switch my goal to implementing the existing
> protocol.
>
> I would be very grateful for any assistance that you might be able to
> provide.  Thanks so much for your help.


Here is a free and open protocol... http://www.hth.com/snap/

You should learn why preambles are used when dealing with wireless 
protocols. Circuit Cellar magazine (http://www.circuitcellar.com/) had an 
article by Jeff Bachiochi about this in their July, 2001 (#132) issue. I 
couldn't find the article on the Web, but you might be able to get a reprint 
from the magazine. It is very informative.

Good luck in your project.

John

You have to have the specs of the TXRX boards and the IO.  You can use x
modem or y modem or z modem or several gernic file transfer protocols,
kermit, just to get going. why write all that code, and figure out the
timing. and fine tune it later


"John Smith" <kd5yikes@mindspring.com> wrote in message
news:qODid.18393$KJ6.5044@newsread1.news.pas.earthlink.net...
>
> <usenet@pobox.com> wrote in message
> news:8ded0ef5.0411022017.542f84a7@posting.google.com...
> >I am a student in an embedded systems design class.  I am planning a
> > project where I'll get two 8051-microcontroller-based development
> > boards with 433 MHz FM transceivers to talk to each other.  Each
> > development board will be connected via RS-232 to a computer running
> > terminal software.  My initial goal is to be able to send some
> > keystrokes back and forth between the two systems.
> >
> > The real challenge of the project is in developing my own wireless
> > protocol to handle packetization, start and stop codes, error
> > detection and correction, line coding, and perhaps collision handling.
> > I am looking for a good tutorial on how to go about such a task--i.e.
> > what options are available and guidelines for implementing them.
> > Something on the web or a book would both be good. I was wondering if
> > you might be able to make a recommendation.
> >
> > Additionally, if you would please recommend any existing protocols
> > that would be sufficient for my application, this would be very
> > helpful because: a) I can use the existing protocol as a reference
> > when developing my own and b) If it turns out to be too difficult to
> > develop my own, I can switch my goal to implementing the existing
> > protocol.
> >
> > I would be very grateful for any assistance that you might be able to
> > provide.  Thanks so much for your help.
>
>
> Here is a free and open protocol... http://www.hth.com/snap/
>
> You should learn why preambles are used when dealing with wireless
> protocols. Circuit Cellar magazine (http://www.circuitcellar.com/) had an
> article by Jeff Bachiochi about this in their July, 2001 (#132) issue. I
> couldn't find the article on the Web, but you might be able to get a
reprint
> from the magazine. It is very informative.
>
> Good luck in your project.
>
> John
>
>

You may want to take this in small pieces.  Get a little bit working, then 
add some
additional functions.  That way you have at least something to show for a 
project
if the entire effort turns out to be much larger than you thought.

Think about the most basic things first:
    How do you turn the transmitter on and off?
    How does the receiver know if it is receiving a signal?

Since you have an RS-232 connection between each radio and it's computer, 
and
are using an ASCII terminal, how do you use ASCII codes to tell the radios
what to do, as opposed to telling the radio what data to send?

Next thing to think about:
    How do you send control codes over the radio link?
    How do you distinguish data you want to send over the link from control
    information you want to send over the link?

I think if you figure out just this much you will have a sucessful project.

    -- Tom



<usenet@pobox.com> wrote in message 
news:8ded0ef5.0411022017.542f84a7@posting.google.com...
>I am a student in an embedded systems design class.  I am planning a
> project where I'll get two 8051-microcontroller-based development
> boards with 433 MHz FM transceivers to talk to each other.  Each
> development board will be connected via RS-232 to a computer running
> terminal software.  My initial goal is to be able to send some
> keystrokes back and forth between the two systems.
>
> The real challenge of the project is in developing my own wireless
> protocol to handle packetization, start and stop codes, error
> detection and correction, line coding, and perhaps collision handling.
> I am looking for a good tutorial on how to go about such a task--i.e.
> what options are available and guidelines for implementing them.
> Something on the web or a book would both be good. I was wondering if
> you might be able to make a recommendation.
>
> Additionally, if you would please recommend any existing protocols
> that would be sufficient for my application, this would be very
> helpful because: a) I can use the existing protocol as a reference
> when developing my own and b) If it turns out to be too difficult to
> develop my own, I can switch my goal to implementing the existing
> protocol.
>
> I would be very grateful for any assistance that you might be able to
> provide.  Thanks so much for your help. 

"torresD" <nospam@nospam.com> wrote in message 
news:2v0h6vF2fnk63U1@uni-berlin.de...
> You have to have the specs of the TXRX boards and the IO.  You can use x
> modem or y modem or z modem or several gernic file transfer protocols,
> kermit, just to get going. why write all that code, and figure out the
> timing. and fine tune it later

I agree that a good way to start is with, e.g., XModem, since the original 
poster apparently has a 'virtual RS-232' connection between the transmitter 
and receiver going already.  In fact, getting XModem or similar working 
should be sufficient for his project.

However, for 'real world' applications, you need to encapsulate the data in 
a much more robust encoding scheme -- at least if you need to go 'reasonable 
distances' with 'reasonable powers.'  Wireless systems typically have bit 
error rates on the order of 10^-2 (1 in 100 bits bad), which will pretty 
much destroy the ability of protocols designed for 'wired' systems (TCP/IP, 
X/Y/ZModem, etc.) to function over any reasonable distance.  Implementing 
sophisticated encoding with error correction would be a good follow-up 
project for the OP.

---Joel Kolstad