[riot-devel] Netdev events questions

Thomas Eichinger thomas at riot-os.org
Sun May 21 18:26:35 CEST 2017


Hi Joakim,

I'm very excited to see the KW41Z supported in 802.15.4 mode.

As for your questions regarding NETDEV_EVENT_RX_COMPLETE:
To my knowledge it is not strictly formalized if it should be sent
before or after transmitting the ACK. Generally I think this depends
on the capabilities of the hardware but as there are also 802.15.4
frames that don't require ACKs I think triggering RX_COMPLETE after
successful reception of a valid frame is reasonable. Also this should
be doable on most hardware to have as consistent behavior as possible.
(The at86rf2xx transceiver line for example doesn't offer a way to
configure this, at least when using auto-ACKs.)

Would you be ok with this approach?

Best, Thomas

On 21 May 2017, at 7:13 PDT(-0700), Joakim NohlgÄrd wrote:

> Dear developers,
> I'm working on a radio driver for the Kinetis KW41Z 802.15.4 radio and
> I have run into some questions regarding when to send the different
> netdev events from my device driver.
>
> Should NETDEV_EVENT_RX_COMPLETE be sent before, or after TX of ACK
> packet is finished?
> Should NETDEV_EVENT_RX_COMPLETE be sent even when the radio detects a
> CRC failure?
>
> My device is using hardware auto-ACK, but I can enable interrupts for
> both the end of RX and at the end of TX ACK. It seem like it would be
> more robust to always wait for TX ACK to be performed, but it may add
> delays if the medium is very busy. It is possible to abort the TX ACK
> after an RX if the CPU issues a new command quickly enough.
>
> Best regards,
> Joakim
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