[Tinyos-help] DTOSH_DATA_LENGTH

[Nahr Elk]

Hi!
Ok, so the best solution in my case (the worst case for RAM) is by compiling
my app with the largest DATA_LENGTH (128) and then it will change the data
payload size if necessary.

But, please just a clarification:

Suppose that I kept DATA_LENGTH to the default value and the payload size
will not exceed this value
However at the Send command level I do something like that :
send(0, MyMsg, 256);

Could this be done??


Thank you!

Best regards,
Nahr Elk

2009/5/19 Razvan Musaloiu-E. <razvanm at cs.jhu.edu>

> Hi!
>
> On Mon, 18 May 2009, Michael Schippling wrote:
>
>  Unless Things Have Changed(TM) in T2, only the length number of bytes
>> is transmitted -- at least over the radio -- so you're not losing
>> bandwidth with a larger DATA_LENGTH. You do waste RAM because buffers
>> are allocated for the max size, which is one reason it's a compile
>> time setting, but that may not matter in your system.
>>
>>
> Thinks haven't changed so what Michael said is correct. The only penalty is
> in RAM. The packets in the air have variable length based on the length
> specified in AMSend.send:
>
>          command error_t send(am_addr_t addr, message_t* msg, uint8_t len);
>
> --
> Razvan ME
>
>  Nahr Elk wrote:
>>
>>> Hi,
>>> Thank you Razvan,
>>> I would like to change the data payload size dynamically according to my
>>> application exigences.
>>> And I am not so convinced that setPayloadLength(message_t* msg, uint8_t
>>> len) is the right solution
>>>
>>> Best regards,
>>> Nahr Elk
>>>
>>> 2009/5/18 Razvan Musaloiu-E. <razvanm at cs.jhu.edu>
>>>
>>>    Hi!
>>>
>>>
>>>    On Sun, 17 May 2009, Nahr Elk wrote:
>>>
>>>        Hi
>>>        Is there any way to change DTOSH_DATA_LENGTH at run time instead
>>>        of at
>>>        compile time ? :)
>>>
>>>
>>>    No. TOSH_DATA_LENGTH is used to allocate the size of the data field
>>>    from message_t (types/message.h) so you cannot alter it at during
>>>    runtime. May I ask why do you want to do this?
>>>
>>>    --
>>>    Razvan ME
>>>
>>>
>>>
>>>
>>
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