I think it depends on the radio. Because some radio can only send/recv a fixed size of packet, for example nRF905.
On Mon, Mar 31, 2008 at 3:06 PM, Kevin Klues <[EMAIL PROTECTED]> wrote: > If you call send() with a length of 2 bytes, only two bytes will be > transmitted over the air. The TOSH_DATA_LENGTH paramter basically > determines the maximum size of the payload you could ever send and > receive. Essentially, it is used to define the size of the data > portion of the message_t struct used to hold messages on your mote. > The length passed to send() is stored in the header portion of > message_t, and when the message is being spooled out over the radio, > theis length field is read to determin how many of the bytes stored in > the data portion of the message should actually be sent. > > Kevin > > On Sun, Mar 30, 2008 at 11:37 PM, David <[EMAIL PROTECTED]> wrote: > > Hi list. > > > > I've taken a look at tep111 and tep126, but there's something which > > isn't clear to me from the teps. > > > > Are the packets transmitted over radio a fixed length or variable > > (based on requested payload length)? > > > > eg, if you leave TOSH_DATA_LENGTH at 28, but send a payload of 2 > > bytes, will the other 26 bytes worth of payload still be sent over > > radio? > > > > I'm asking because one of my apps needs to send as small as possible > > packets (reduce battery usage, and to hog the radio freqeuncy for as > > short as possible). However, I would like the app to still be able to > > receive larger packets. Otherwise all the apps in the mote network > > need to have the smaller TOSH_DATA_LENGTH, which is bothersome. > > > > Any insights on this subject? > > > > David. > > _______________________________________________ > > Tinyos-help mailing list > > [email protected] > > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > > > > -- > ~Kevin > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > -- Best Regards, SANG JUNJUN http://www.tinysys.cn/
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