NRF52 - ESB - Receiving duplicate packets

[nordicfreak]

We are having some issues with ESB, it seems the automatic ACKs are not working properly and we get spammed with a lot of duplicates.

We believe the issue is because we start some function immediately when NRF_ESB_EVENT_RX_RECEIVED is triggered and because of this it doesn't have time to send an ACK.

How can we delay without blocking the CPU before starting our function?

This seems to work but is it the best way?

//event triggered

for(int i=0; i<50; i++){
nrf_delay_us(10);
}

//start function

[Kenneth]

Hello,

Typically the ESB run on relative high priority, so even if the application may be executing code with lower priority it should not affect the ESB libray handle the transmisson of acknowledgements. 

If you have enabled ack you should allow sufficient time (e.g 500us) on reception of packet to ensure ack can be sent out. If you don't care about ack, it is possible to disable ack when transmitting the packet.

Kenneth

[nordicfreak]

Hi,

I added a 1ms delay before processing the RX events, and I still get duplicates

[Kenneth]

Gazell:
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/gzll_02_user_guide.html 
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/gzll_examples_device_and_host.html 

PTX is called device, and PRX is called host in Gazell.

Kenneth

[nordicfreak]

As far as i remember, Gazell has a pretty small max payload size. Is there any code available demonstrating bidirectional communication using parge payloads?

[Kenneth]

32byte payload either way should be supported as-is I believe, do not believe larger is possible no.

Kenneth

[nordicfreak]

Can you please provide some sample code for Gazell RX and TX, for sending 300 byte payload?

How about bi-directional, can I change between host and device fast enough? Any other tips?

[Kenneth]

Hello,

I opened the example project I previously linked for Gazell, I can see that the project supports bidirectional data (see that the host call nrf_gzll_add_packet_to_tx_fifo() to add data to ACK).

I can find frmo nrf_gzll_constants.h that the max payload length is 32bytes as I suspected:
#define NRF_GZLL_CONST_MAX_PAYLOAD_LENGTH    32                     ///< Maximum allowed payload length in bytes.

So this means that if you want to send 300bytes either way, then you need to fragment the data into 32byte chunks.

Gazell was never meant for dynamic switching between host and device no.

Kenneth

[nordicfreak]

This will be tricky if I need to send a 300 bytes reply fragmented in multiple acks.

Can someone from your team write a proof of concept maybe? I am sure it will benefit the whole community.

[Kenneth]

Sorry, that is not possible. If you have specific questions I can answer them, but in terms of software development you will need to use the example as starting point and develop you own project. Personally I would have considered using the first 1-2bytes as a header for the application, e.g. information about what packet this was in a sequence of x packets etc. But I don't have any example or guidance on how this can be done in specific no.

Kenneth

[nordicfreak]

Great, thank you for the help.