CodeWarrior Development ToolsのトピックCCA - SMAC

CCA - SMAC

vitorgabriel100 — Wed, 16 Oct 2019 14:44:47 GMT

Hello,

I was studying the SMAC protocol and i had some doubts about CCA - Clear Channel Assessment. I would like to know if it's a manual that explain its functions in a more detailed way or someone can explain me how it functions.

Thanks.

Re: CCA - SMAC

Sebastian_Del_Rio — Fri, 18 Oct 2019 16:07:53 GMT

Hi Vítor, I hope you're doing well!

SMAC is mounted on top of an 802.15.4 physical layer. This means that Clear Channel Assessment can be done by a request from the upper layers to the PHY layer, by creating a message to the lower layer.

However, the way that it's implemented in our Stack, the CCA is done automatically by the PHY layer.

You can read more about SMAC and 802.15.4 in the documentation included with the KW41Z's SDK.

The documentation can be found in the SDK's path, here:

<…\SDK_SDK_2.2.1_FRDM-KW41Z\docs\wireless>

Best regards,

Sebastian

Re: CCA - SMAC

vitorgabriel100 — Fri, 18 Oct 2019 18:00:39 GMT

Thanks, but I can not understand the real purpose of CCA, what is its function?

Regards

Vítor Caitité

Re: CCA - SMAC

Sebastian_Del_Rio — Mon, 21 Oct 2019 15:28:24 GMT

Hi Vitor,

CCA is a necessary process for the 802.15.4 communications protocol to make sure that no other message is being sent at the same time as a new message, so, when trying to transmit data, the PHY layer checks the transmission medium to see if the channel is clear and no other data is being transmitted.

If no data is being transmitted, and the channel is clear, then, a new message can be transmitted.

You can get more information about the 802.15.4 wireless communication standard and the NXP implementation of the stack in the documentation included with the KW41Z's SDK, in the following path:

<…\SDK_SDK_2.2.1_FRDM-KW41Z\docs\wireless\IEEE 802.15.4>

Best regards,

Sebastian