How to achieve a measured conductive Tx Power of +21 dBm using any NCS sample app?

[Starbuck]

My Goal:  To measure a conductive Tx Power of +21 dBm using any NCS sample app running on Fanstel's BT840XE module, which includes the nRF52840 plus the +22 dBm Skyworks SKY66112 integrated FEM.

Problem Statement:  So far the highest conductive Tx Power I have measured is 3.3 dBm using the attached NCS v2.3.0 peripheral_hr_coded sample, which has my modifications to control the Skyworks SKY66112 FEM in the nrf52840dk_nrf52840.overlay and overlay-nrf52840dk.conf files.  However, I am able to measure +21 dBm using the attached BT840X_AT_PC_221028.hex file I received from Fanstel, which is based on the nRF5 SDK.

Please let me know if you see anything wrong with my nrf52840dk_nrf52840.overlay or overlay-nrf52840dk.conf files.  I am fine with going back to previous NCS versions if necessary.  However, I'm aware of Pull Request 10143 and DRGN-18568 being marked as fixed in NCS v2.3.0.

NOTE:  I added the tx_power.c/h modules and gated them with #define ENABLE_TX_PWR_DYNAMIC_CONTROL in tx_power.h just so I could print out the TX Power value that actually gets initialized at run time after bt_enable() is called in main().  This requires CONFIG_BT_CTLR_TX_PWR_DYNAMIC_CONTROL=y at the top of the overlay-nrf52840dk.conf file.

Any and all ideas are welcome.

Thanks,

Starbuck

4628.peripheral_hr_coded_fem_NCS_v2.3.0.zip

3730.BT840X_AT_PC_221028.zip

[Vidar Berg]

Hello,

Sorry for the delay. I compared the pinout in your overlay with the pinout Fanstel suggest in the "Control Skyworks Power Amplifier" section of their product specification (https://static1.squarespace.com/static/561459a2e4b0b39f5cefa12e/t/63de927a519c1b69364b15f2/1675530877718/BT840F-p+Product+Specifications.pdf) and it looks like you may have gotten the CSD and CPS pins wrong? CPS controls the bypass mode and if I am reading things correctly, you have CSD set to '1' and connected to the input CPS input on the FEM.

By the way, it looks like you have a neat tool there for measuring TX output power. I have not seen anything like it before.

Best regards,

Vidar

  

[Starbuck]

Regarding my RF Power Meter, it is really nice and portable (affordable too).  I travel a lot and I'm getting into flying FPV drones as a hobby of mine so I'm always looking for compact portable test equipment. I highly recommend it!

Here's a link to it:  https://www.immersionrc.com/fpv-products/rfpwrv2/