What I sent applies to all motes supported by T2:
/opt/tinyos-2.x/tos/chips/cc2420/CC2420.h:70:#define TOSH_DATA_LENGTH 28
And we know that telos and micaz use CC2420
/opt/tinyos-2.x/tos/types/message.h:
#ifndef TOSH_DATA_LENGTH
#define TOSH_DATA_LENGTH 28
#endif
SInce all other chips do not define TOSH_DATA_LENGTH, so the value is always 28.
#define TOSH_DATA_LENGTH 28
#endif
SInce all other chips do not define TOSH_DATA_LENGTH, so the value is always 28.
Rgds,
Tie
On 10/16/06, Michael Schippling <[EMAIL PROTECTED]> wrote:
The common compiler technique is to silently pad fields to the natural boundary,
so probably the MPS gcc will stick a pad after a single byte to even things out.
I believe there are some compiler directives in TOS to control the padding, but
I've only used the micas so I haven't payed any attention.
I am a little surprised that what appears to be a base level define in message.h
has been changed in T2, I would have expected to see that happen in the platform
specific structs, maybe what Tie Luo sent was specific to telos motes.
...oh well...
MS
Jay Taneja wrote:
> I know that the Telos/Tmote implementations generally use 28 byte
> payloads because the 16-bit micro has some difficulties dealing with
> odd bytelength fields. The Mica family, on the other hand, has 8-bit
> micros. I am not quite sure of how exactly the MSP430 handles odd
> bytelength fields - it may just expand them by a byte so they are of
> even bytelength. Something to investigate...
>
> -jay
>
> On 10/15/06, Michael Schippling <[EMAIL PROTECTED]> wrote:
>
>> Ah, sorry, I should have said in tos 1.x it's 29.
>> I wasn't aware that it appears to be all different in v2.
>>
>> The main caviets are that longer messages have a higher
>> probability of getting a bit error which kills the whole
>> thing, and shorter messages have more header overhead.
>> Finding the right balance is of the essence.
>> MS
>>
>>
>> Tie Luo wrote:
>> > /opt/tinyos-2.x/tos/types/message.h:7:#define TOSH_DATA_LENGTH 28
>> > /opt/tinyos-2.x/tos/chips/cc2420/CC2420.h:70:#define
>> TOSH_DATA_LENGTH 28
>> > /opt/tinyos-2.x/tos/chips/xe1205/XE1205.h:102:#define
>> TOSH_DATA_LENGTH 28
>> > I did not find anywhere defining it to be 29.
>> >
>> > p.s. If anyone point out the caveats of changing its value, I
>> appreciate it.
>> >
>> > Tie
>> >
>> > On 10/15/06, *Michael Schippling* < [EMAIL PROTECTED]
>> > <mailto:[EMAIL PROTECTED]>> wrote:
>> >
>> > Where did you find 28? The 'main' tos/types/AM.h file defaults
>> to 29.
>> > And yes, you can change it. But search back on this list for
>> caveats.
>> > MS
>> >
>> >
>> > Tie Luo wrote:
>> > > It can be found in TinyOS source code that TOSH_DATA_LENGTH is
>> > defined
>> > > to be 28, but I found in this mail archive people are saying 29,
>> > which
>> > > one is correct?
>> > >
>> > > Another question is, since 802.15.4 supports up to 127-byte
>> > packet, does
>> > > that mean we can redefine TOSH_DATA_LENGTH to be larger, say
>> 100, as
>> > > long as the total packet size does not exceed 127?
>> > > --
>> > > Regards,
>> > > Tie
>> > >
>> > >
>> > >
>> >
>> ------------------------------------------------------------------------
>> > >
>> > > _______________________________________________
>> > > Tinyos-help mailing list
>> > > [email protected]
>> > <mailto: [email protected]>
>> > >
>> >
>> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>> >
>> <https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help>
>>
>> >
>> >
>> >
>> >
>> > --
>> > Regards,
>> > Tie
>> _______________________________________________
>> Tinyos-help mailing list
>> [email protected]
>> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>>
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Regards,
Tie
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