[Tinyos-devel] timestamps in seriallisten/sflisten etc.

[David Gay]

On Thu, Jun 26, 2008 at 1:27 PM, Philip Levis <pal at cs.stanford.edu> wrote:
>
> On Jun 26, 2008, at 12:59 PM, Razvan Musaloiu-E. wrote:
>
>>>
>>
>> I'm a little confused. What is a "packet source"? In the way I'm thinking,
>> the code that handles the direct serial communication to the mote is the
>> only one that is required to read the clock and put a timestamp.
>
> The point is that serial@ is a protocol; it doesn't define an endpoint. It's
> possible to connect two PCs via serial cable and have them talk the serial
> protocol. As I said before, while this might seem a bit unlikely, there are
> other protocols that can connect directly to motes, such as network@, which
> is essentially the serial protocol over a TCP socket.
>
> It would be a very bad idea to bind protocols to particular kinds of
> endpoints. I.e., we could say that network@ and serial@ do not have
> timestamps, while sf@ does. But this could get a little weird; it would mean
> that the serial and network packet sources would need to insert NULL
> timestamps,

Well no, the network@ and serial@ packet sources would be the ones
inserting the current time as the timestamp.

> otherwise you have different packet formats depending on which
> source you choose. I.e.,
>
> java net.tinyos.tools.MsgReader <source>
>
> would need to know whether packets generated by the source have timestamps
> or not.

Well no, the packet source gives it a timestamp - MsgReader (or the
serial forwarder) doesn't care where that timestamp came from.

David