Hi! The SPI is a byte-oriented protocol, so it can transmit any number of bytes. The radios have internal buffers, which is 128 bytes both on the cc2420 and rf230 chips (telosb and iris). There are some header, length and other fields, so you are left with 114 bytes of useful payload.
Best, Miklos On Tue, Jan 18, 2011 at 1:01 PM, Sergio Valcarcel <serteck...@gmail.com> wrote: > Hi Ranal, > > I am not an expert, but some colleagues from me made many experiments > and I remember they told me that the problem is also in the SPI buffer > which is 128bytes maximum. So if you remove 14 bytes needed for the > header, you can only use 114bytes. > > Cheers! > Sergop > > On Tue, Jan 18, 2011 at 4:14 AM, ranal fernando <ranalferna...@live.com> > wrote: >> hi, >> >> my understanding is the following. correct me if i'm wrong. >> >> Since packet length type is uint8_t we can only send 256 bytes (including >> header data etc.) in cc2420 radio. (used by micaz telosb). >> >> so in the case of iris you need to split it. i think even for telosb & micaz >> need splitting 320 bytes. >> >> thanks >> >> ranal >> >>> Date: Mon, 17 Jan 2011 10:23:34 +0100 >>> From: mmar...@math.u-szeged.hu >>> To: loic.pfis...@epfl.ch >>> CC: tinyos-help@millennium.berkeley.edu >>> Subject: Re: [Tinyos-help] How to send a message bigger than 2kb >>> >>> You have to do it yourself. Miklos >>> >>> On Mon, Jan 17, 2011 at 10:09 AM, Pfister Loic <loic.pfis...@epfl.ch> >>> wrote: >>> > Hi, >>> > >>> > I need to send a message of 2560 bits --> 320 bytes. >>> > >>> > From what I read in the mailing list, you are able to send packet up to >>> > 114 >>> > byte with an iris mote. >>> > >>> > So I will need to send three packets to transmit my full message. >>> > >>> > So is there any function that split my packet in three automatically ? >>> > Or Will I need to implement by myself to split the packet in three, and >>> > rebuilt it on the other size ? >>> > >>> > Thanks a lot in advance >>> > >>> > loic >>> > >>> > _______________________________________________ >>> > Tinyos-help mailing list >>> > Tinyos-help@millennium.berkeley.edu >>> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >>> > >>> _______________________________________________ >>> Tinyos-help mailing list >>> Tinyos-help@millennium.berkeley.edu >>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> >> _______________________________________________ >> Tinyos-help mailing list >> Tinyos-help@millennium.berkeley.edu >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> > _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
