Porting ncs example code to Fanstel BT840X that has an internal skyworks PA/LNA

[Orangepeel]

I am looking to take example codes for the nrf52840dk and run them on a Fanstel BT840X EV board. I am looking at the central and peripheral coded low data rate firmware but want to achieve a much greater range by using the RF amp and LNA. Can anyone point me to some examples that might demonstrate of give some idea how to do this. I am using NRF connect SDK 2.2.99 with visual studio. I have got the Fanstel BT840X range test code working and I have been able to port the examples for the nrf52840dk to the Fanstel BT840X EV board but cannot get the extended range. Does the code need to control the switching of the PA/LNA as at the moment I have the PA fixed on and LNA off.

[Amanda Hsieh]

Hi, 

Take a look at https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.2.0/nrf/ug_radio_fem.html#adding-support-for-skyworks-front-end-module and this post. 

Regards,
Amanda H.

[Orangepeel]

HI Amanda,

Yes I am aware of that link and the post is the most relevant to my question that I have found.

I do get this message "CONFIG_MPSL_FEM was assigned the value y, but got the value n. Missing dependencies:
MPSL_FEM_ANY_SUPPORT" when I add CONFIG_MPSL_FEM=y to my prj.config file.

I dont have a great understanding of how the PA and LNA are switched. I assume that the BT driver knows when to configure this switch. I am controlling with GPIO the PA and LNA lines into the Skyworks device so I assume that I am not controlling well enough these lines as I have a very poor range. I have been measuring the power draw and I do get peak power consumption of around 200mA.

Any more assistance gratefully recievied.

[Orangepeel]

I can force the PA on by setting the GPIO and I do get the 250mA consumption but as this forces the PA on it does not go to receive mode with the LNA so the link only has minimal range. When I alter the PA and LNA pins to something I can scope I do not see the pins toggling which is what I think I should expect.

[Amanda Hsieh]

Hi, 

The MPSL fem driver can control a skyworks fem, but it only controls the CTX and CRX pins. The CPS and CHL must be handled manually by the application. I assume you want 20dBm output power, for this, you need to set the CHL pin high and the CPS pin low.  The fem driver will automatically set the output power from the SoC to get the desired final output power(after the PA), the default will be 0dBm, so the output power of the SoC will be turned down so that the final output power is 0dBm. To change this you need to change the config:

CONFIG_BT_CTLR_TX_PWR_ANTENNA=20

There is also an issue in 2.3.0 and older that causes the output power to not be set correctly when in a connection. Please update to at least 2.4.0 as the issue has been fixed in this version.

-Amanda H.

[Orangepeel]

Hi Amanda, I now have a much higher power consumption during TX and consequently greater range. I do not get the same power consumption as seen from using Fanstel BT840X example hex. The hex code peaks at 225mA and my code peaks at 200mA. Any idea why that might be?

[Orangepeel]

Also, How to I check that the module is running at 125Khz. Are there any settings that force 125Khz?

[Amanda Hsieh]

Hi, 

Orangepeel said:

I now have a much higher power consumption during TX and consequently greater range.

You should check the product specification for the power consumption of Fanstel BT840X/sky66112-11 in TX mode. 

Orangepeel said:

The hex code peaks at 225mA and my code peaks at 200mA.

What is the hex you are comparing to? Not sure what your code is, but it depends on the functions in the code. 

Orangepeel said:

How to I check that the module is running at 125Khz. Are there any settings that force 125Kh

What module do you mean here?

-Amanda H.

[Orangepeel]

Sorry, I meant how can you check that the data rate is 125Khz for long range?

[Amanda Hsieh]

Hi, 

Do you mean coded phy data rate 125 kbps?

If so, you can take a look at the Central Heart Rate Monitor with Coded PHY and the Peripheral Heart Rate Monitor with Coded PHY samples and check with nRF Sinffer. 

-Amanda H.

[Orangepeel]

Hi, I downloaded the software required for the nRF sniffer but soon as I choose the option scan and follow devices on LE Coded PHY, under extcap interface settings, it captures some other BT data and then does not capture anything more. I note that the LED on the dev board also stops flashing once this setting is set.

[Amanda Hsieh]

It needs an extra nRF device to program as an nRF Sniffer. Please note that not all the nRF devices can support LE Coded PHY. See the Supported Features table in the Minimum requirements doc. Please create a new support case if you still have issues. The latest issue is away from the original scope. 

-Amanda H.