Nrf24l01 prx plos_cnt

Projects Networking, Protocols, and Devices
1

In the Nordic data sheet I was unable to find a function/register to be used on the PRX side to (i) identify an incoming packet as a retry, and (ii) identify that retry chronologically.

In other words, my question is; is PLOS_CNT (which origines in PTX) transmitted?

What I am imagining is, if PRX receives a packet identified as the 10th retry, PRX can then know that nine preceding packets (of identical payload) were lost. If after issuing an ack in response to retry ten, PRX receives the same packet/payload again with a retry-ID chronologically subsequent to retry number ten, we know that PTX did not detect PRX's ack to retry number 10.

I think this data can useful in assessing the quality of the RF environment. Additionally, in cases of asymmetrical hardware resources, the resource-rich side can be tasked with hosting more of the channel surveying, analysis and planning. ( In my situation, PTX runs on a coin cell, with 4k of flash, while PRX is on a wall adapter with 32k of flash. )

Thanks for any input.

Dan
San Jose, CA

2

The PTX side does not update the "header" of the packet to account for the numbers of retries, but it counts them in a separate register. You would have to do that in your code. You can change the retry count to none, and when you get the signal that the TX failed, you can "modify the payload" to update a "retry count" field.

3

Thanks for the comment/info. I think I will address this limitation by having PTX, in response to excessive retries, set the PA to 0db, set retries to a high number, and then package the PLOS_CNT into subsequent transmissions. PRX seeing that PTX has messaged that it has exceeded a loss threshold and is now in high power, sets it's power to 0db, and then executes a channel hopping scheme.

Thanks,

Dan