Best way to dynamically switch channels with an ESB

RE: Best way to dynamically switch channels with an ESB

Susheel Nuguru — Mon, 17 Feb 2025 13:27:14 GMT

Those functions are disabling different parts of ESB as ESB start have started many different things, ESB stop needs to stop all those things start in the start. The documentation of these functions can be found here which will explain you the difference between these functions

esb_suspend()
esb_stop_rx()
esb_disable()

RE: Best way to dynamically switch channels with an ESB

DX_HK — Mon, 17 Feb 2025 10:38:35 GMT

Thank you for your comment.
As you say, the actual elapsed time was shorter, significantly shorter than 180us.
Perhaps the measurement method was inappropriate and other processing times were included.

However, while trying to switch channels, a new question arose.

First of all, it seems that there are multiple functions that disable ESB.

esb_suspend()
esb_stop_rx()
esb_disable()

esb_disable() seems inappropriate, but please tell me the difference between these functions and their uses.

RE: Best way to dynamically switch channels with an ESB

Susheel Nuguru — Fri, 07 Feb 2025 12:46:05 GMT

Hi Hiroyuki-san

[quote user=""]But it doesn't seem optimal. Is there a better solution?[/quote]

Let us look at the code of esb_stop_rx()

int esb_stop_rx(void)
{
	if ((esb_state != ESB_STATE_PRX) && (esb_state != ESB_STATE_PRX_SEND_ACK)) {
		return -EINVAL;
	}

	esb_ppi_for_txrx_clear(true, false, fast_switching);
	esb_fem_reset();

	nrf_radio_shorts_disable(NRF_RADIO, 0xFFFFFFFF);
	nrf_radio_int_disable(NRF_RADIO, 0xFFFFFFFF);

	on_radio_disabled = NULL;

	nrf_radio_event_clear(NRF_RADIO, NRF_RADIO_EVENT_DISABLED);
	nrf_radio_task_trigger(NRF_RADIO, NRF_RADIO_TASK_DISABLE);

	while (!nrf_radio_event_check(NRF_RADIO, NRF_RADIO_EVENT_DISABLED)) {
		/* wait for register to settle */
	}

	nrf_radio_event_clear(NRF_RADIO, NRF_RADIO_EVENT_DISABLED);

	esb_state = ESB_STATE_IDLE;

	return 0;
}

In this the most time consuming things I see are the NRF_RADIO_TASK_DISABLE and esb_fem_reset.

I am a bit confused why the FEM calls here are not fenced with a config to see if you have a FEM in your product or not. Are you having FEM in your product? If not, try to optimize the esb initialization and deinitalization to remove fem stuff.

The other time consuming thing is NRF_RADIO_TASK_DISABLE and from the spec

t_TXDISABLE

Time between DISABLE task and DISABLED event when the radio was in TX and mode is set to 1Msps

So it seems like the 180us only on esb_stop_rx does not add up unless the FEM processing is taking significant of this time.