Good morning to everyone. I'm having some trouble trying to activate the Front End Module (FEM) SKY66112 that it is integrated with the nrf52840 in a ev-BT840X fanstel board. This module increments the TX signal power in order to get some distance between devices and that they keeping talking using the Wirepas protocol (kinda like BLE). We use also the wirepas SDK (github.com/.../wm-sdk)
Searching for some help in Github I found that a simmilar board (pca10112) that uses another FEM (nrf21540). We tried to re-use the code adapting it to our FEM using its datasheet, but we never succed. The main problem right now is that after two devices get further than10-15 meters, the Wirepas signal is lost.
Our current materials are the following:
- A pca10040 that acts as sink. We see all the information through Wirepas Terminal (mainly TX, RX power and if the periodical message arrives or not).
- Fanstel ev-bt840-fe with a SKY66112 (FEM, PA and LNA). Acts as a simple node emmiting a message after two seconds. See the schematics in the following picture:
First, we modified the files related to the power table, extracted from the radio module from nrf52 and wirepas SDK (C:\wirepas\wm-sdk\mcu\nrf\nrf52\hal\radio\radio_power_table_nrf52840_4dBm.h)
The used pins, according to the BT840X information page 18 (static1.squarespace.com/.../BT840F_Product Specifications.pdf)
(The pin 13 is not the one where the antenna is connected, but we were uncapable of finding this pin and we don’t know if it is mandatory to turn on the FEM).
The different FEM states, related to the SKY66112 documentation, page 5 (www.skyworksinc.com/.../4C7B484628BA46BDADCB2E2AACDFA1ED.pdf)
This is the Fem_Init() function, with all the pins configured according to the TX state at the beginning as the sky66112 datasheets indicates:
Finally, our problem: We are uncapable of turning on this FEM. We read all the documentation, where indicates that this FEM consumes around ~300mA. We use a power supply so we can measure the current that our node consumes. Even when we tried multiple different strategies and different boards, the current consumption is always 10-20mA.
We frankly has searched all the internet trying to find a solution, but another problem is that most of the information are related to the Nordic SDK, so some solutions are not viable using the Wirepas SDK.
Please, if you have any clue, it would be very important to us on how to activate this FEM and increment the range of Wirepas messages. Any advice is welcome.
Thank you for your time, best regards
