Openthread with FreeRTOS

[Asgeir]

Hi!
I've successfully set op an OpenThread MQTT broker using a Rasperry Pi and nrf52 dongle and I am able to publish and subscribe to and from my computer by flashing the mqttsn_client_subscriber and mqttsn_client_publisher examples to my nrf52840 DK.

I want to incorporate thread communication into a larger project on the nrf52840 DK using FreeRTOS. My first step has been trying to modify the mqttsn_client_subscriber example to incorporate FreeRTOS. However I have not had much success.

Does the SDK provide examples of OpenThread with FreeRTOS or are there other sources I can consult?

[Edvin]

Hello,

There is one example that uses the openthread stack and FreeRTOS:

SDK_for_Thread_and_Zigbee_4.1.0\examples\thread\freertos_coap_server

Perhaps you can use this example for reference.

Best regards,

Edvin

[Asgeir]

Hi!
I've tried this unsuccessfully.

I modified the mqttsn_client_subscriber example some, making it connect to the broker and subscribe to topic automatically, not using the buttons.
This solution works well. 



However when i try to implement the same solution in FreeRTOS, using the freertos_coap_server as a reference, it doesn't work. The program does not connect to the gateway etc. 


There seems to be an issue with running the mqttsn_evt_handler, perhaps this is related to using the app_scheduler in the program? I am not sure, but the events are not triggered. 

Here is my code: https://github.com/hunshamar/freertos_openthread

Do you have any suggestions for making this work? I am not too experienced with FreeRTOS or the nordic SDK, so any help would be appreciated. 

-Asgeir

[Asgeir]

I gave this a try, but unfortunately it did not work. I even tried a brand new nrf52 dongle.
The problem seems to be with the FreeRTOS program. I tried adding another task that only toggles an LED on the board, and this one freezes as well. The problem seems to be with the mqqtsn_client_search_gateway() function that is run at the start of the program.

When i exclude this piece of code at least the led blinking tasks runs normally. But if I run this function the program seems to halt. 

Also if I just comment out all the FreeRTOS -stuff and run the openthread-task as a while-loop it works. So there seems to be some conflict with FreeRTOS and the mqtt event handler or something similar.  

[Edvin]

Ok. Thank you for checking. Can you please zip your project (preferably the one that also toggles the led, which also freezes) here, so that I can try to recreate it on my DK.

Best regards,

Edvin

[Asgeir]

I uploaded it to github,  https://github.com/hunshamar/freertos_openthread, which can also be downloaded as a zip. But do you want the full SDK folder with the project zipped? 

-Asgeir

[Edvin]

I saw that repo, but which of the projects is it? And what IDE did you use to set up the project? I tried the freertos_coap_server\pca10056\blank\ses and armgcc, but none of them compiled in an unmodified SDK2.0.0. Where should I place the project file, and what IDE do you use? Please make sure that it compiles in an unmodified SDK.

SDK2.0.0 is a bit old, so you can consider to move to SDK4.1.0, but we can look into it in the SDK2.0.0 first.

BR,

Edvin

[Asgeir]

The projects are explained in the readme. The "freertos_coap_server" is the freertos openthread mqtt program. 

I am able to compile it in an unmodified SDK2.0.0. I tried downloading a new SDK now and tested it. I copied the files from the github repo into SDK/examples-folder. I used VS code to modify the code, but to compile it i ran the makefile in pca/10056/blank/armgcc using a terminal. You can see where i placed the project files in the picture. Does this not work for you?

Kind regards, Asgeir. 

[Edvin]

Yes. It was probably what it said earlier as well, but I guess it wasn't an error:

So, I am currently working from home, and can't monitor the LEDs, because the DK is connected in my work computer in the office, so I added the line:

NRF_LOG_INFO("led task"); right before toggling the led in the while loop.

I saw that it was only printed once, and I wanted to debug, so I had to port the segger project that you provided. However, running that, I see that it is printed regularly (LED1_BLINK_INTERVAL).

Can you try the attached project (unzip in the same location as you had your project) and check if it behaves the same, or if the LED keeps blinking in your case?

6281.freertos_coap_server.zip

[Asgeir]

It behaves the same. The LED only blinks once. When i remove the call to mqttsn_client_search_gateway(), the blinking tasks works as expected. 

[Edvin]

Did you test the SES (segger embedded Studio) project that I attatched in the previous reply? Does it behave the same there?

[Asgeir]

I only tested the armgcc solution with make. Should i install SES and try the SES file?

[Edvin]

Hello,

I experimented a bit more. It seems like you receive a hardfault, but I am not yet sure why. Please check the attached project:

5460.freertos_coap_server_2.zip

Put it in the same location as your current project. 

Also, open hardfault_implementation.c and modify the function HardFault_process() to look like this:

/*lint -save -e14 */
__WEAK void HardFault_process(HardFault_stack_t * p_stack)
{
    // Restart the system by default
    //NVIC_SystemReset();
    while (true)
    {
        NRF_LOG_PROCESS();
    }
}
/*lint -restore */

And monitor the RTT log.

I have to ask a colleague of mine, but he is not in today. I'll check with him, hopefully in the beginning of next week.

BR,

Edvin