nRF5340 BLE transmit power

RE: nRF5340 BLE transmit power

Starbuck — Mon, 20 Feb 2023 16:21:53 GMT

For NCS v2.2.0, you now don't need to edit hci_rpmsg or create your own serialization solution. For example, I was able to run the HCI Power Control sample app on the app core of the nRF5340 and was able to read the default TX Power with only the unmodified running on the network core.

RE: nRF5340 BLE transmit power

Karl Ylvisaker — Mon, 11 Jul 2022 07:37:01 GMT

Hello again, Wilson Chen

1. By mpsl_tx_power or TX power envelope, during the FCC certificate testing in between BLE 1M, 2M channels, can we set different power limit and change dynamically or need to flash FW or data in and reboot to tak effective?

Tx power envelope can be set for every channel on every PHY separately. That means that if the customer prepares two sets of Tx power envelopes: one for BLE 1M, the other for BLE 2M, each describing the envelope to be applied for channels 0-39 when operating on a given PHY, then that should be applied dynamically.

Thing to take into account here is that BLE Tx power is interpreted as SoC power. If any Front End Module is used, the user must calculate the envelopes on their own, offseting them with gain added by the FEM, if needed.

2. Even BLE is hopping mode in natural, Nordic should have test command to fix the channel for power meter or spectrum analyzer reading the power (RMS), correct?

Could you clarify what you mean by this question? Are you asking whether we have an API that will make the communication happen on a specific channel (no hopping)? If not, please clarify what you are asking about here.

3. why the FEM (nRF21540) mode control is comoing from nRF9160 instead of nRF5340, while most control pins of nRF21540 coming from nRF5340

The developers were not quite sure what was meant with this question, since none of the Nordic designs are using nRF9160 with a nRF5340 and nRF21540 - is this in reference to a custom board you are working with? If so, could you provide some more information about how this is set up, so that we may better advise you.

Best regards,
Karl

RE: nRF5340 BLE transmit power

Karl Ylvisaker — Fri, 08 Jul 2022 16:05:18 GMT

Hello Wilson Chen,

Thank you for your patience. The summer holidays have begun here in Norway, and so DevZone is operating at reduced capacity.

I will be handling this inquiry while Øivind is away.
I have forwarded your follow-up questions to the developers, and I will let you know as soon as they get back to me.

Best regards,
Karl

RE: nRF5340 BLE transmit power

WilsonChen — Fri, 01 Jul 2022 14:56:45 GMT

Hi Oivind,

Yes and please have the delegagted expert to answer me two question though I learn some background from your statement.

The third question is, why the FEM (nRF21540) mode control is comoing from nRF9160 instead of nRF5340, while most control pins of nRF21540 coming from nRF5340

Thanks,

Wilson Chen

RE: nRF5340 BLE transmit power

Øivind — Fri, 01 Jul 2022 12:25:57 GMT

Hi,

I've spoken to a developer about this. Since MPSL can only be on the network core, its APIs are only callable from the network core. There are a couple of ways to handle this.

One way would be to configure the power envelope and call the MPSL function from the application running on the network core. This would require you to edit hci_rpmsg.

Another way would be to create your own serialization solution to pass calls from the application core to the network core. nRF RPC may be useful for this. https://github.com/nrfconnect/sdk-nrfxlib/tree/main/nrf_rpc

As far as I know, the power envelope is normally supposed to be configured on initialization.

Another caveat is that this output power limit will only apply to the SOC, and not any front-end modules. You may need to "offset" the envelope to account for the additional Tx gain added by the amplifier.

I am aware this does not answer all your questions, however I am going on vacation starting next week, so I am marking this case to be assigned to another engineer.

RE: nRF5340 BLE transmit power

WilsonChen — Wed, 22 Jun 2022 03:21:15 GMT

Hi Oivind,

Simple questions:

2. Even BLE is hopping mode in natural, Nordic should have test command to fix the channel for power meter or spectrum analyzer reading the power (RMS), correct?

Thanks,

Wilson

RE: nRF5340 BLE transmit power

WilsonChen — Fri, 17 Jun 2022 23:56:20 GMT

Hi Oivind,

Thanks and we are looking forward your input

In temrs of BLE certificate for FCC, we need to know the exact capability of different channel setting with different power index.

Per MPSL it mentioons: The current implementation of the FEM support does not implement the SPI interface or MODE pin support and does not change the transmission power after the initialization. Does it mean MPSL is one-time programming or the library/data can be stored in NVM or flash and edited then fill back?

Thanks,

Wilson

RE: nRF5340 BLE transmit power

Øivind — Fri, 17 Jun 2022 12:44:17 GMT

Hi,

MPSL has an api for setting TX power per PHY:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/nrfxlib/mpsl/doc/tx_power_control.html

https://github.com/nrfconnect/sdk-nrfxlib/blob/v1.9.1/mpsl/include/mpsl_tx_power.h#L62-L76

And Zephyr has a sample for setting TX power using hci commands:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/zephyr/samples/bluetooth/hci_pwr_ctrl/README.html

I am not completely sure if it is possible to change the power index of different PHYs using hci commands, or if there are extra considerations when working with nRF5340 or nRF21540. I will look into this and get back to you over the weekend.