nrf51 ACK retransmission.

[Elliott Makin]

Hi there

Can you clarify a point for me?

Quoting from Gazell link layer user guide: "If only the ACK packet sent from the Host to the Device is lost, but both the initial packet and the subsequent retransmission attempts are being successfully received by the Host, the repeated packets will be discarded by the Host, but the ACK packets will still be sent in return to the Device. This prevents the application receiving duplicate data packets at the Host."

There is an image below this paragraph that indicates when the repeat packet is received the ACK is not sent contrary to the text above. Which is it?

[Hung Bui]

Hi Elliott,

I assume you were talking about the figure with the description "Example on failing package transaction." here.

In the figure we wanted to demonstrate when a transaction is failed. The second ACK packet was not "not sent", it was sent but got lost, not received by Device, because of interference for example.

And when the last packet from Device to Host also went missing, and the third ACK was not sent, we will have nrf_gzll_device_tx_failed() call back return.

The figure doesn't really demonstrating what discussed in the paragraph right above it.