ESB PTX and PRX with no ACK - how to wait for TX ready

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Hung Bui — Tue, 18 Mar 2025 11:33:26 GMT

Hi Peter,
I think you are hitting the limit. You can't expect the actual payload data to be equal to theoretical bit rate. This is due to:

- Overhead: address byte, preamble, CRC

- Radio switching time. The radio has to switch between TX and RX. Even with FAST_SWITCHING the switching time is 40us.

The longer the packet the less number of radio switching. However , longer packet may have higher chance of interference and get corrupted. If you enable re-transmission the whole bigger packet will have to be retransmitted. So you need to balance between high through put and waste on packet loss and retransmission.

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Peter Langer Keysoft — Mon, 17 Mar 2025 15:44:12 GMT

Thanks for your answer,

Activating ESB_NEVER_DISABLE_TX is excluded from the activated ESB_FAST_SWITCHING.

When I activated ESB_NEVER_DISABLE_TX to YES ESB handler was not handled. Only FAST_SWITCHING is good solution, but he have data rate only 3.34Mbps (50 x 256B / 29ms).

I want to know why data rate is not 4Mbps and why activating ESB_NEVER_DISABLE_TX stops the handler service.

Here is oscillogpraph for one ESB packet and 50x ESB packets

I want to ask if when setting CONFIG_ESB_TX_FIFO_SIZE=50 and sending 50 ESB packets in quick succession, do I have to wait for TX READY from the ESB handler.

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Hung Bui — Mon, 17 Mar 2025 15:17:39 GMT

Hi Peter,

[quote user="Peter Langer Keysoft sro"]CONFIG_ESB_TX_FIFO_SIZE
CONFIG_ESB_RX_FIFO_SIZE[/quote]

They are the length of the buffers, aka how many packets you can queue:

[quote user="Peter Langer Keysoft sro"]

What values should they have when we want to send more than 10 ESB packets in a row?

[/quote]

If you want to be able to queue 10 ESB packet to send then you set CONFIG_ESB_TX_FIFO_SIZE=10.

[quote user="Peter Langer Keysoft sro"]

What about the "PIPE" variable in the "esb_payload" structure? Should I, as a user, set it?

[/quote]

Basically it's the logical address of each node that's connected to the PRX/PTX.

[quote user="Peter Langer Keysoft sro"]

How to properly use "esb_flush_tx()" when I want to have minimal delay between ESB packets?

[/quote]

I don't think using this can reduce the delay between ESB packet.

Please try the CONFIG_ESB_FAST_SWITCHING=y to see it reduce the time it take between packets.

Regarding the Kconfig never disable TX:

config ESB_NEVER_DISABLE_TX
    select EXPERIMENTAL
    bool "Never disable radio transmission stage"
    help
      This option changes the radio behavior so that the
      transmitter remains IDLE between transmissions instead of being disabled.
      This is applicable only when the packet is not acknowledged. Otherwise,
      the radio emitter needs to be turned off to enable the radio receiver.
      This reduces delay between consecutive transmissions but consumes more energy.

From what written here it should be able to reduce the time between TX packets. Please try testing on the SDK's sample.

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Peter Langer Keysoft — Mon, 17 Mar 2025 10:43:29 GMT

Hi,

Now we are testing the modified original sample. We have increased the ESB payload to 251 bytes (CONFIG_ESB_MAX_PAYLOAD_LENGTH=251). What is the role of the following parameters?
CONFIG_ESB_TX_FIFO_SIZE
CONFIG_ESB_RX_FIFO_SIZE

What values should they have when we want to send more than 10 ESB packets in a row?

What about the "PIPE" variable in the "esb_payload" structure? Should I, as a user, set it?

How to properly use "esb_flush_tx()" when I want to have minimal delay between ESB packets?

******************

When I changed the parameter on PTX and PRX "Never turn off radio transmission stage" to YES, communication stopped.

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Hung Bui — Mon, 17 Mar 2025 09:25:57 GMT

Hi Peter,

I'm not so sure why you don't have the callback. On the sample the callback is triggered regardless if noack is set or not. My understanding is that if noack is set

ESB_EVENT_TX_SUCCESS will always returned.

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Peter Langer Keysoft — Fri, 14 Mar 2025 16:15:08 GMT

Hi,

thanks for the reply. I tested the original sample with your suggestions. It working.

In the sample I see that PTX waits for the "ready" variable which is handled in the ESB handler. But in our project this handler is not handled when we turn off ACK (noACK = true). What could be the reason?

RE: ESB PTX and PRX with no ACK - how to wait for TX ready

Hung Bui — Fri, 14 Mar 2025 14:29:09 GMT

Hi Peter,

Could you try to test with the esb samples with the following
On both PTX and PRX:

config.selective_auto_ack = true;

And on PTX:

tx_payload.noack = true;

Do you see the packets arrive on the PRX and no ACK on the PTX ?

Do you have other board for example nRF52 or nRF54L to test ? Just want to make sure it's not the issue with NRF54H cpurad