Hello, On Fri, Jan 24, 2014 at 8:16 AM, Varka Bhadram <var...@cdac.in> wrote: > hai... > > IEEE-802.15.4 devices that are there in the market right now are softmac > devices ex: cc2420,cc2520. So it can only detect whether the channel is free > or not. For example in case of cc2520 ,the h/w is providing us the one GPIO > pin which is CCA. It will be high when the channel is free. If the channel > is busy (GPIO_CCA = 0), generating the backoff and resending the packet is > not in the h/w (cc2520) provided the channel is free. So we need to take > care of generating the backoff and resending the packet if the channel is > free from the microcontroller side. > > For this to be implemented there are two approaches that i thought of,,, > > 1. This logic can be at the mac level in kernel (mac802154). We can export > that symbol.... > 2. Logic can be at the driver code in the ieee802154_ops-> (*tx) : means in > the transmission function(by checking GPIO_CCA in case of cc2520)
CCA definitely goes to the tx function. You might have a function to generate ACK packet in the mac layer, but ACK response should go to the tx function (see the semantics for it). > > > If i am wrong please correct me.... > > > Regards, > Bhadram > > > On January 23, 2014 at 4:15 PM Dmitry Eremin-Solenikov > <dbarysh...@gmail.com> wrote: >> Hello, >> >> On Thu, Jan 23, 2014 at 8:04 AM, Varka Bhadram <var...@cdac.in> wrote: >> > hai.... >> > >> > Where is the CSMA-CA implementation ? Is it there in H/w (IEEE-802.15.4 >> > radio example:cc2520) itself or is it there at the mac802154 in linux ? >> >> CSMA/CA has so strict timing requirements (logical, you check that the >> channel is >> free and then you immediately should start to transfer), that it's >> just unpractical >> and unrealistic to implement any CSMA/CA / CCA handling in the kernel >> itself. >> >> Either your hardware should implement that for you, or you are out of luck >> and just hope that the channel is clear. >> >> -- >> With best wishes >> Dmitry > > ------------------------------------------------------------------------------------------------------------------------------- > This e-mail is for the sole use of the intended recipient(s) and may > contain confidential and privileged information. If you are not the > intended recipient, please contact the sender by reply e-mail and destroy > all copies and the original message. Any unauthorized review, use, > disclosure, dissemination, forwarding, printing or copying of this email > is strictly prohibited and appropriate legal action will be taken. > ------------------------------------------------------------------------------------------------------------------------------- -- With best wishes Dmitry ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Linux-zigbee-devel mailing list Linux-zigbee-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-zigbee-devel
