How to get RSSI in the direction_finding_connectionless_rx example on nRF52833?

[Sener]

Hi,

I want to simply get RSSI at each scan in the connection less example (direction_finding_connectionless_rx).
I have running two nRF52833-DK. One is flashed with RX and the other with RX example.

I'm using the nordic NCS SDK v1.8.0 with softdevice s140 v7.3.0.

The devices are communicating to each others nice and easy. But, RSSI readings at each scan show a constant value (-127)

When I debug it (using RTT Viewer and Debug terminal), I get this;

RSSI looks always -127.

I can only see some different RSSI readings during initial talk between the two devices (anchor and tag)

Any input greatly appreciated.

[Simonr]

Hi

First off, the nRFConnect SDK does not use SoftDevices like the S140 (they belong in the nRF5 SDK), as the nRFConnect SDK rather uses a SoftDevice controller, so if you've tried mashing the SoftDevice onto an nRFConnect SDK project that might be causing trouble.

It seems to state that the TX power is 127 as well, which seems fishy to me. 

One is flashed with RX and the other with RX example.

I assume you mean that one is flashed with the DF connectionless TX (beacon) sample, and one is flashed with the DF connectionless RX (locator) sample.

I think what is happening is that you're mixing up AoA and AoD modes which for some reason makes the RSSI off on the receiver side. Please try setting up the projects again and read the setup instructions carefully when doing so.

Best regards,

Simon

[Sener]

Hi Simonr,

Thank you very much for your answer. I haven't noticed that you've replied until I find it in my e-mail box instead of here under my entry.

Yes, I meant there RX and TX. I've already corrected in my entry. 

In fact that, the setup and everything were relatively easy. I have started to setup thing with the help of "nRF Connect for Desktop v3.10.0" => "Toolchain Manager" => Open Segger Embedded Studio. it was more or less Next by Next.
I am not sure if I did anything with Softdevice.
And then I've pick the project(s) and I could build the project(s) flawlessly.

I have also made a few changes in the config files only for RTT Viewer with J-Link.
And I added a line in the CMakeList.txt => SET(OVERLAY_CONFIG "overlay-aoa.conf")
I did those changes for the both RX and TX examples. But not sure if I must use this OVERLAY_CONFIG for RX version as well. Because, in the ReadME file, it doesn't say so.

Here is where I pick the projects and build right away.

So far, I have done/tried whatever I could gather around in the devzone and manuals. But not everything make sense and you have to figure out yourself. For example, there was a saying like that; "To build this sample with angle of arrival mode only, set ``OVERLAY_CONFIG`` to :file:`overlay-aoa.conf`." This cost me a lot of time to figure out what it means exactly.
Finally I found that it meant you have to write a line in the `CMakeLists.txt` file:
=> SET(OVERLAY_CONFIG "overlay-aoa.conf")

However, unfortunately, I have still the same result, no sensible RSSI and tx-power as you pointed.

I've also seen some others in the devzone. Their output was also similiar to mine. I think I am not alone with that.
This entry shows the same issue (although it was not the main complain in there);
https://devzone.nordicsemi.com/f/nordic-q-a/83857/ncs-1-8-direction_finding_connectionless_rx-aoa-can-t-work

Do you have any further idea for me?

Thanks.

Best regards,

Sener

[Simonr]

Hi

No, you don't need this overlay-aoa.conf file in the locator application.

I would select the projects found in the \ncs\v1.8.0\nrf\samples path rather than the Zephyr path if I were you, as those are specifically tailored for the nRF52833 and NRF5340 devices.

If you're new to development with the nRFConnect SDK I would recommend using the Visual Studio Code and the nRFConnect SDK extension, which lets you add overlay files when setting up a project for example. Do you have an antenna array on the locator side and have you configured the antenna matrix to work in Angle of Arrival mode as explained in the documentation? This is required to get correct results.

Best regards,

Simon

[Sener]

Hi Simonr,

Yeah, actually I am already using the one you suggested (C:\nRF5\ncs\v1.8.0\nrf\samples).

Yes, I can consider myself new with nRF development but old with SES. This is why I have started with it. But, I have also Visual Code included necessary extensions, just  I didn't check there yet.

Simonr said:

No, you don't need this overlay-aoa.conf file in the locator application.

Interesting, in the Readme file this was the suggestion at least for AoD not sure for AoA though. A bit confusing, I don't know.

Simonr said:

Do you have an antenna array on the locator side and have you configured the antenna matrix to work in Angle of Arrival mode as explained in the documentation? This is required to get correct results.

No, I don't have any array antenna yet. In fact that I contacted to Nordic regional sales director (Patrick) and I asked him your antenna design with 12 antennas so I can make one myself (in the case you don't have one otherwise I can buy), but he didn't return me back since Tuesday. If you can help me on this, I would appreciate that. I mean if you can share the info regarding the antenna design or such.

One more remark, I am now struggling to debug using RTT Viewer. I can't see the logs anymore for some reason.
But I've noticed that my config setting keep reverting back. For example a setting "CONFIG_UART_CONSOLE=n"
keeps revert back to "CONFIG_UART_CONSOLE=y".
The config file is at this location;
C:\nRF5\ncs\v1.8.0\nrf\samples\bluetooth\direction_finding_connectionless_rx\build_nrf52833dk_nrf52833\zephyr\.config

What do you think about it?

Last but not least;

Do we have another sample project pair (like in the same sense TX and RX) you can suggest for monitoring RSSI with nRF82533? No need AoA or AoD.

Thank you.

Best regards,
Sener

[Simonr]

Hi

The ReadMe file covers both setup for using AoD and AoA (AoA is what we would recommend). So on the locator side, you can skip the AoD overlay file and focus on the antenna array configuration instead.

I have pinged the sales manager of your region and they should get back to you soon.

The CONFIG_UART_CONSOLE should be set in the prj.conf file of your project C:\...\v1.8.0\nrf\samples\bluetooth\direction_finding_connectionless_tx\prj.conf

Other examples using RSSI include I.E. the central_hr sample that will detect and print the RSSI of advertising heart rate monitor peripheral samples.

Best regards,

Simon