Hi, I am trying to determine how many tries CC2420TransmitP will make if Congestionbackoff occurs i.e. When CSMA-CA is enabled, which is by default, for the first time CCA pin is checked if medium is busy or not, if medium is busy then initialbackoff occurs then after initialbackoff time is passed then medium is checked again and if it is still busy then congestionbackoff occurs.
By looking into CC2420TransmitP what I can understand is that after congestionBackoff() is called it calls BackoffTimer.start(myCongestionBackoff), BackoffTimer calls attemptSend() and it calls congestionBackoff() again if medium is busy. What I want to know is that is there a limit between this cycle that if congestionBackoff() is called this many times and the medium is still not free drop the packet? In IEEE 802.15.4 the number of retries is 3 but in TransmitP I don't see any limit. Also FIFO buffer of CC2420 is 128 bytes what will happen to next incoming packets? Regards, Tipu Sultan Masters Student in Network, Services and Systems. KTH - Royal Institute of Technology, Stockholm, Sweden
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