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  • Case ID: 300156
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Radio Test with Skyworks FEM + NRF52840

Brosnan

Hi,

I needed assistance to get the SKY66403-11 FEM working with the Radio Test Example in VS Code, for certification testing (FCC, CE etc). I am using the NCS 2.2.0 SDK.  I am using a custom board with nRF52840 SoC and it has the LFXO present. 

I have added the device tree node as depicted below in the sample code, created as an existing project.:

Are there any additional changes required beside these to be done to get the FEM working because while building this I get the following build error. 

 PS: Just wanted to mention that I tried running the Radio Test Example directly without adding the support for the FEM and that works as expected.

Thanks in Advance

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  • 0

    Hi,

    You might need to include Kconfig option CONFIG_MPSL_FEM_SIMPLE_GPIO=y for FEM device that has generic 2-pin control interface. You can read more about this option here.

    Best regards,
    Dejan

  • 0 in reply to dejans

    Hello Dejans,

    Thanks for the quick response.

    I tried adding that option. I get the following Cmake error:

    Do I require to add any other option along with this one?

    The error seems to say I cannot change these options as they not "user-configurable", is my understanding correct here?

  • 0 in reply to Brosnan

    Hi,

    I have seen the same issue in NCS v2.2.0. However, everything worked for me as expected with NCS v2.0.0. Could you downgrade to NCS version v2.0.0 and test radio sample again?
    In the build configuration, you should have the options below added as Extra CMake arguments



    Best regards,
    Dejan

  • 0 in reply to dejans

    Hi,

    I was able to build the Radio test sample without any build errors with v2.0.0, though got a couple of warnings. Would want to know why can't I use the latest SDK version for the same.

    But when I send any commands to start the Tx, the device resets. Please refer the image below.

    If I build the code as is without the FEM node in the device tree. The Tx commands work fine.

  • 0 in reply to Brosnan

    Hi,

    I have seen board resets in NCS v2.2.0 which were not there for me when using NCS v2.0.0. I tested the sample with Skyworks FEM on nRF52840-DK using the following configuration in nrf52840dk_nrf52840.overlay




    Brosnan said:
    Would want to know why can't I use the latest SDK version for the same.

    There is a pull request for this issue.

    Best regards,
    Dejan

  • 0 in reply to dejans

    Hi,

    Brosnan said:
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    nrf_radio_fem: SKY66403 {
    compatible = "skyworks,sky66403-11", "generic-fem-two-ctrl-pins";
    ctx-gpios = <&gpio1 01 GPIO_ACTIVE_HIGH>;
    crx-gpios = <&gpio1 04 GPIO_ACTIVE_HIGH>;
    chl-gpios = <&gpio1 06 GPIO_ACTIVE_HIGH>;
    cps-gpios = <&gpio0 24 GPIO_ACTIVE_HIGH>;
    };
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

    I have added my node as mentioned earlier in the nrf52840dk_nrf52840.dts file. Should that matter?

  • 0 in reply to Brosnan

    Hi,

    It matters what is the location of your nrf52840dk_nrf52840.dts file. If you put it in your project folder, it will not work as you expect. However, modifying existing nrf52840dk_nrf52840.dts file which is located in \v2.0.0\zephyr\boards\arm\nrf52840dk_nrf52840 should work as expected. You can check if Skyworks configuration is included after building the project by looking at zephyr.dts file which is located in your build\zephyr folder. In order to avoid modifying existing dts file, it is recommended to use nrf52840dk_nrf52840.overlay file instead. You can put this overlay file in your project directory.

    Best regards,
    Dejan

Reply
  • 0 in reply to Brosnan

    Hi,

    It matters what is the location of your nrf52840dk_nrf52840.dts file. If you put it in your project folder, it will not work as you expect. However, modifying existing nrf52840dk_nrf52840.dts file which is located in \v2.0.0\zephyr\boards\arm\nrf52840dk_nrf52840 should work as expected. You can check if Skyworks configuration is included after building the project by looking at zephyr.dts file which is located in your build\zephyr folder. In order to avoid modifying existing dts file, it is recommended to use nrf52840dk_nrf52840.overlay file instead. You can put this overlay file in your project directory.

    Best regards,
    Dejan

Children
  • 0 in reply to dejans

    Hi,

    I am using the Radio test sample as is (as an existing project), and haven't created a separate project directory.

    As you suggested to check the build\zephyr folder, I did and found the changes for the FEM node to be present. As I am not very well versed to create a custom .overlay file, didn't do that and instead changed the <board>.dts file directly.

    I'll just post the warnings I get after building here as well for reference.

    Any other pointers for what I should check/do next.

  • 0 in reply to Brosnan

    Hi,

    If you want to try the way I suggested, please make sure that you have unmodified file \v2.0.0\zephyr\boards\arm\nrf52840dk_nrf52840\nrf52840dk_nrf52840.dts. When you have verified that this dts file is unmodified, proceed with steps outlined below.

    1. Make freestanding application in VS Code based on radio_test sample in NCS v2.0.0. When the application is made, radio_test directory is created. This is what I referred to as your project directory. You don't need to have separate project directory other than radio_test.
    2. Inside your project directory (radio_test), create a file called nrf52840dk_nrf52840.overlay. The content of this file should be (in case you use nRF52840-DK) as shown below



    3. Create a build configuration in VS Code and add following Extra CMake arguments



    4. Build your application

    You may still see some warnings, but the build should be successful.

    Best regards,
    Dejan

  • 0 in reply to dejans

    Hi,

    I made the file as you described. Below is the content and location of the same. Also reverted the changes on .dts

    After building I do get a new error.

  • 0 in reply to Brosnan

    Hi,

    I cannot reproduce this behavior. It seems that something is wrong with your environment. There might be some changes to the environment which cause this error.

    In VS Code, you could try to add radio_sample as an existing application instead of creating a new one and then do the same steps as before. In this case, you would have your nrf52840dk_nrf52840.overlay file inside \v2.0.0\nrf\samples\peripheral\radio_test folder. If this doesn't help, I would suggest that you try on another computer or reinstall your environment.

    Best regards,
    Dejan

  • 0 in reply to dejans

    Hi,

    Okay i'll try to start from scratch and see if it works.

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