Brian,
Great! That really helped! Thank you!
Best regards,
Pedro
On 6/30/07, Brian Mulanda <[EMAIL PROTECTED]> wrote:
Pedro,
In terms of memory allocation, the data bytes are always 28. However,
during transmission, usually,
only the actual data bytes (in your case, the size of the struct) are
relayed.
-Brian
On 6/30/07, Pedro Almeida <[EMAIL PROTECTED]> wrote:
>
> Hey, Brian!
>
> So that means it always is 28 bytes, regardless of being "filled" or
> not? So if my struct is 1 or 28 bytes, the data bytes are always 28?
>
> Thanks!
>
>
> On 6/30/07, Brian Mulanda <[EMAIL PROTECTED]> wrote:
> >
> >
> > TOSH_DATA_LENGTH represents the max data payload; in your case, the
> > struct. The size of
> > the struct is allocated out of the 28 bytes.
> >
> > I am not certain of the total frame size; I think it is,
> > coincidentally, at least 28 (13+15). In the event
> > that escape bytes are included, to handle "reserved" bytes appearing
> > in the data, it could be more.
> >
> > -Brian
> >
> > On 6/29/07, Pedro Almeida <[EMAIL PROTECTED]> wrote:
> >
> > > Hello all;
> > >
> > > I would like to know the exact length of the 802.15.4 frame. The
> > > reason that i'd like to know the exact length is because i need to do some
> > > duty cycles numbers and one of the inputs is the frame length. It would
seem
> > > to equal the payload, but given it makes no sense to me the payload on the
> > > serial frame, i might as well doubt i can figure the length on the
> > > 802.15.4's.
> > >
> > > So according to TEP 125:
> > >
> > > The TinyOS 802.15.4 T-frame format is as follows:
> > >
> > >
+-------------------+---------+------------------------------+--------------+
> > > | 802.15.4 Header | AM type | data | 802.15.4 CRC |
> > >
> > >
+-------------------+---------+------------------------------+--------------+
> > >
> > > I presume the 802.15.4 Header, as according to CC2420.h, to be 10
> > > bytes:
> > >
> > > typedef nx_struct cc2420_header_t {
> > > nxle_uint8_t length;
> > > nxle_uint16_t fcf;
> > > nxle_uint8_t dsn;
> > > nxle_uint16_t destpan;
> > > nxle_uint16_t dest;
> > > nxle_uint16_t src;
> > >
> > > /** I-Frame 6LowPAN interoperability byte */
> > > #ifdef CC2420_IFRAME_TYPE
> > > nxle_uint8_t network;
> > > #endif
> > >
> > > nxle_uint8_t type;
> > > } cc2420_header_t;
> > >
> > > AM Type, according to previous struct, another byte before "data".
> > > Total: 11.
> > >
> > > I suppose CRC to be 2 extra bytes added in the end. Total: 13
> > >
> > > The "data" field intrigues me.
> > >
> > > I see this being defined in CC2420.h
> > >
> > > #ifndef TOSH_DATA_LENGTH
> > > #define TOSH_DATA_LENGTH 28
> > > #endif
> > >
> > > Does this mean it's a fixed length that gets 'populated' according
> > > to each different situation (making a fixed total of 42 bytes), or is 28 a
> > > max, or am i understanding this all wrong?
> > > The struct in TestNetwork is 15 bytes. Would that means the total
> > > frame size is 13+15=28 bytes? Or is there anything extra added?
> > >
> > > Any help greatly appreciated!
> > > Thanks,
> > >
> > > Pedro
> > >
> > >
> > > _______________________________________________
> > > Tinyos-help mailing list
> > > [email protected]
> > > https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> > >
> > >
> >
> >
>
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