On Sep 7, 10:43pm, Paul B. Webster wrote:
> Subject: Re: Serial Transfer using pic16c84

>   And no wonder, having "bitten off" quite a wide range of issues in one
> go.  This general field is referred to as "packet radio" and quite a
> popular aspect of Amateur Radio, at least for those sub-set of ops whose
> mentation can get past a Morse key <G>.
>
>   I shall presume that Jason is consideriang a LAN system using pre-
> built class-licensed milliwatt modules from http://www.qwikradio.com or
> similar.  I further presume he was not considering using full HDLC
> protocol but rather asynchronous ASCII.  Nevertheless, software-wise, he
> is looking at writing a full TNC (Terminal Node Controller) type system,
> and should certainly examine the behaviour, if not the availability of
> commercial systems such as the TAPR Pocket TNC or Micropower devices.
> Search starting from  http://www.tapr.org./  and read awhile.
>
>   In addition, he implies the possible use of a "broadcast" mode where
> data is received by multiple devices simultaneously.  This is not to be
> confused with the basic packet radio premise of multiple "conversations"
> or "connections" sharing the channel by some means and achieving error-
> free data transfer by checksums and acknowledgements with serial
> numbering of packets.
>
>   The problem of error correction in a broadcast mode is a thorny one
> indeed, generally implemented by serialising broadcast packets with non-
> cylic (non-modulo at least) identifiers and individual receivers issuing
> numbered NAKs after a timeout rather than ACKs.  Even this is limited.
> But I had best ask first, is this what Jason was asking, or does he just
> want a "connected mode" Packet protocol?

Well I guess due to my inexperence I have not seen all the posibilities that
may run into.   What I am trying to do is very simply send asynchronous between
two pics.   I guess the term broadcast may have been two broad.

I will try to explain more.   What I have is a pic that is in a payload that
flies with a high alitude balloon.  What happens is that using amature radio
frequences I will send a DTMF command to a reciver which  will pass this tone
to a decoder.  The decoder then sends out 4 bits of information.   I am reading
this information in at Port B of a PIC16C84.   I then want to take this data
and resend it over two small class-licensed milliwatt modules.  The moduldes
that I have are designed to send digital data acting as a transparent link.  So
what I want to do is to that the information that is stored in port b and send
it out over thses modules to another pic that is about 15 feet away near the
balloon.  This information coming over the radio is then checked and if the
correct code is sent the pic will perform the the given instruction.   If an
incorrect instruction is received nothing happens and the system start
listening again.

I have all the parts working except for the transmitting of the data.
So basicall all I need to do is to send a start bit,  data,  and stop bit.
But I am having a lot of trouble doing this.  Can anyone help

Jason Alexander