Hi . with the help of radio message_t you can send 128 bytes of data at a
time .
But out of that 128 byte ..some bytes are reserved for some extra data which
is not accessible to us.
So around 117 bytes can be sent at a time .
Initially that maximum limit is 28 as u said. You have to increase it . in
message_t and your platform specific radio chip header file. As in my case
(telosb) cc2240.h . There you will find TOSH_DATA_LENGTH . Change that field
to whatever you want below 117 bytes .
One more thing always compare length of data you are sending to maximum
limit . Which can be found from
call Send.maxPayloadLength() ;

cheers ..


>
> Date: Sun, 16 Aug 2009 21:30:25 -0400
> From: Akankshu Dhawan <[email protected]>
> Subject: [Tinyos-help] message structure , large buffers ?
> To: [email protected]
> Message-ID:
>        <[email protected]>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi All
> I am having some problem with the message_t structure. I am creating a
> buffer size 1000 and as readStream.read(10) gets done in 0.01 sec. The
> message_t TEP has informed me that the message payload can be of size 28
> bytes. But if my buffer size is 1000 I cannot send it through this message
> structure.
> 1. Will I have to break this buffer into small packets while sending ? In
> case I have to do this will I need multiple buffers so that I do not loose
> out on audio signals while I am busing sending ? How long does transmission
> take on MICA2 motes ?
>
>
> 2. Is there any other way to transmit large buffers ?
>
> I am looking at Anti Theft application as well since it is using ReadStream
> for the acceleration components and that has been really useful but even
> that application has used buffer size of 10 which was similar to
> Oscilloscope. 2 bytes per buffer element means I can have a maximum of 14
> elements in my buffer. Is my judgement true ?
>
>
>
> Looking forward to hearing from you.
>
>
> Thanks
> Akankshu
>
> --
> First they ignore you, then they laugh at you, then they fight you, then
> you
> win.
> - Mahatma Gandhi
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-- 
With Best Regards
Himanshu Barve
M.Tech Electrical Engineering (Power System)
IIT Kharagpur , West Bengal , India
Ph: - +91 9775201181
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