How to get RSSI of an OpenThread sleepy end device

[kaushalyasat]

Hi,

I have a set of OpenThread CoAP clients configured as speepy end devices to preserve battery. I need to obtain RSSI values of each of the CoAP clients. From CoAP server I can use CLI to query 'ot child n' to get RSSI value of the connected child nodes. I am going through the CLI files  to detect how this is done via CLI, but it seems a lengthy process.

How can I retrieve the RSSI values from CoAP server API? (i.e. without going through the CLI)

Cheers,

Kaushalya

[kaushalyasat]

I think I found the function 'otThreadGetChildInfoById' in cli.cpp line 1046. I think this is where the CLI gets the info regarding a particular child. 

Here I need to get the pointer to thread instance. How can I get it?

Is there better ways of getting the real time (or near real time) RSSI or link quality measurements of OpenThread network? This is for the range detection purposes, not distance measurements. 

Cheers,

Kaushalya

[Sigurd Hellesvik]

I am going through the CLI files  to detect how this is done via CLI, but it seems a lengthy process.

Yes, it is a bit lengthy, but it is the method I generally find best for figuring out how to use OpenThread.

kaushalyasat said:

Here I need to get the pointer to thread instance. How can I get it?

openthread_get_default_instance()

kaushalyasat said:

Is there better ways of getting the real time (or near real time) RSSI or link quality measurements of OpenThread network? This is for the range detection purposes, not distance measurements. 

See  RSSI measurement in OpenThread? . Does this answer your question?

Regards,
Sigurd Hellesvik

[Sigurd Hellesvik]

By using otThreadGetChildInfoById

Regards,
Sigurd Hellesvik

[kaushalyasat]

Hi Sigurd, Thanks, but isnt this function meant to be executed from the leader? What I need is a way to read the child's own RSSI data, from the child itself. 

Can we retrieve 'otThreadLinkInfo' from the child (or end device)? 

May be 'otLinkRawGetRssi ()' function?

Cheers,

Kaushalya

[kaushalyasat]

I tried 

RSSI = otLinkRawGetRssi (openthread_get_default_instance());

but resulted in a compile error saying 'undefined reference to `otLinkRawGetRssi'. I found the function defined in 'C:\ncs\v2.0.0\modules\lib\openthread\src\core\api\link_raw_api.cpp'. But the function is not included in the build because  

#if OPENTHREAD_RADIO || OPENTHREAD_CONFIG_LINK_RAW_ENABLE

{...

}

So apparently none of these symbols are defined anywhere. 

I tried defining these symbols in prj.conf, but resulted in a config error. So these are not build config flags it seems.

I found them in  'C:\ncs\v2.0.0\modules\lib\openthread\src\ncp\ncp_config.h', but when I try to include this in my source, the file path cannot be resolved. 

I tried '#include "C:\ncs\v2.0.0\modules\lib\openthread\src\ncp\ncp_config.h"', then is could be located, but even after #defineing the symbols, the 'otLinkRawGetRssi' seems not enabled.

I am out of ideas now. Some light??

[Sigurd Hellesvik]

kaushalyasat said:

Thanks, but isnt this function meant to be executed from the leader? What I need is a way to read the child's own RSSI data, from the child itself. 

Ah, I misunderstood.

How about otThreadGetParentLastRssi()?

Regards,
Sigurd Hellesvik

[kaushalyasat]

Hi Sigurd, Brilliant. That solved my issue. I guess this is not an averaged RSSI, but that is ok for us. 

Thanks again.

Kaushalya

[Sigurd Hellesvik]

kaushalyasat said:

I guess this is not an averaged RSSI

Then maybe otThreadGetParentAverageRssi() is what you need?

Regards,
Sigurd Hellesvik