2014/1/24 Christophe Aeschlimann <c.aeschlim...@acn-group.ch>
> Hi,
>
> Le 24.01.2014 05:16, Varka Bhadram a écrit :
> > 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.
>
> I haven't used any of these radio but a quick glance through the
> data-sheet seems to indicate that you are wrong about that.
>
> Search for STXONCCA.
>
> 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)
> > If i am wrong please correct me....
> > Regards,
> > Bhadram
>
> As already said by Dmitry the strict timing requirements make this task
> difficult for a Linux implementation. You probably want an RTOS to
> implement that.
>
Or, probably RT-PREEMPT patch will be a good start point in your research
if you prefer to work with Linux stack.
> --
> Christophe Aeschlimann
>
> Embedded Software Engineer & IT Manager
> ACN Advanced Communications Networks S.A.
> 2000 - Neuchâtel, Switzerland
> Tel. +41 32 724 74 31
>
>
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