why nRF54L15 cannot use the automatic mpsl power split?

[Ziyao Zhou]

Hi

I have a question regardin why nRF54L15 cannot use the automatic mpsl power split?

If I want to use ESB + nRF21540 with automatic TXP control, what should I do?

#if !(defined(CONFIG_SOC_SERIES_NRF54H) || defined(CONFIG_SOC_SERIES_NRF54L))
	int32_t err;
	mpsl_tx_power_split_t tx_power;

	(void)mpsl_fem_tx_power_split(esb_cfg.tx_output_power, &tx_power,
				      convert_bitrate_to_mpsl_phy(esb_cfg.bitrate),
				      (RADIO_BASE_FREQUENCY + esb_addr.rf_channel), false);

	err = mpsl_fem_pa_power_control_set(tx_power.fem_pa_power_control);
	if (err) {
		/* Should not happen. */
		__ASSERT_NO_MSG(false);
	}

#ifdef NRF53_SERIES
	bool high_voltage = false;

	if (tx_power.radio_tx_power > 0) {
		high_voltage = true;
		tx_power.radio_tx_power -= NRF5340_HIGH_VOLTAGE_GAIN;
	}

	nrf_vreqctrl_radio_high_voltage_set(NRF_VREQCTRL_NS, high_voltage);
#endif /* NRF53_SERIES */

	nrf_radio_txpower_set(NRF_RADIO, tx_power.radio_tx_power);
#else
	nrf_radio_txpower_set(NRF_RADIO, dbm_to_nrf_radio_txpower(esb_cfg.tx_output_power));
#endif /* !(defined(CONFIG_SOC_SERIES_NRF54H) || defined(CONFIG_SOC_SERIES_NRF54L)) */

[Elfving]

Hi,

First of all, could you explain a bit how you are seeing this not working on your side? I would assume nRF54L supported power split.

Regards,

Elfving

[Ziyao Zhou]

Hi，

I have go througput this ticket 

https://devzone.nordicsemi.com/f/nordic-q-a/122031/nrf21540-fem-tx-power-with-esb

I found that they can use esb_set_tx_power(22), when I try on my nRF54L15+21540 it can not run. it will show that:

"TX power to enumerator conversion failed, defaulting to 0 dBm "

And then I go through SDK 3.3.0 esb.c, find that the power cannot split under nRF54L15. 

[Elfving]

Hi, I believe the issue is that ESB on the nRF54 series does not "officially" support FEM yet.

[Ziyao Zhou]

Do you know when it will be officially support?

What could I do now, if I want to use 20 dBm，I have to set MCU to 0 dBm and FEM with 20 dBm?

[Elfving]

Ziyao Zhou said:

Do you know when it will be officially support?

For this, you would have to ask your local RSM (regional sales manager), let me know if you need his contact info.

Ziyao Zhou said:

What could I do now, if I want to use 20 dBm，I have to set MCU to 0 dBm and FEM with 20 dBm?

This is currently not supported by NCS. Currently, for the nRF54, we can set the power level to that supported by the SoC.