MQTT-SN won't connect as SED while "THREAD_RADIO_MODE_RX_OFF_WHEN_IDLE"

[rogerarchibald]

Hello,

I'm struggling to connect to an MQTT-SN Gateway when the device is configured for low power.  Currently using MAC-OS Catalina 10.15.3, SES version 4.42 and have tried Nordic + Thread SDK's version 3.2 and version 4.

I can't register an MQTT-SN device when the thread_instance_init is called with ".radio_mode" set to "THREAD_RADIO_MODE_RX_OFF_WHEN_IDLE"  If I build the project with this configuration, the gateway configuration fails and returns "app: MQTT-SN event: Gateway discovery result: 0x3"

I can change the radio mode to "THREAD_RADIO_MODE_RX_ON_WHEN_IDLE" and it all works as expected, but the current consumption is unacceptably high for my proposed application.  I have looked at the gateway configuration on my MQTT-SN gateway and I don't see anything obvious that could change here to solve this issue.

Ultimately, I guess I'm asking"

  A: Can other people successfully register/publish/subscribe to MQTT using the "thread_mqtt_sn_sleepy_publisher_pcba10056" example project?  

  B: If not, is there a workaround for this to be able to use MQTT-SN as a SED?

Thanks and Best Regards,

Roger

[rogerarchibald]

To clarify, I'm seeing this with the NRF52840-DK

[Marjeris Romero]

Hi,

Have you seen the test guidelines for the sleepy subscriber and publisher projects on the infocenter? Are you using our thread border router as the MQTT-SN gateway or a third party's? Are you struggling to connect the example out of the box or have you made any modifications?

Best regards,

Marjeris

[rogerarchibald]

Hi Marjeris,

I have reviewed the test guidelines and I don't think there's anything I'm missing there (I could always be wrong on that).  I am using a Raspberry Pi with the Nordic Thread Border Router image and using an NRF52840 Dongle as the NCP.  I am pretty much using the SDK examples out of the box, the only modification I've made is to the sdk_config.h file to clear the NRF_FPRINTF_FLAG_AUTOMATIC_CR_ON_LF_ENABLED  flag for debugging within SES.  I've also set the channel and PANID over the CLI to connect to my network.  Those are the only changes.

The mqttsn_client_publisher example works as described in the test guidelines.  The mqttsn_sleepy_publisher works as described if I change the thread configuration radio mode to RX_ON_WHILE_IDLE, but out of the box it isn't able to connect to the gateway.

[Jørgen Holmefjord]

Hi,

I tested this on my setup. Initially, I got an error when changing the radio mode to :

<info> app: MQTT-SN event: Gateway discovery result: 0x3.

I then set the poll_period and child_timeout parameters, similar to the MQTT-SN Sleepy Subscriber example:

thread_configuration_t thread_configuration =
{
    .radio_mode        = THREAD_RADIO_MODE_RX_OFF_WHEN_IDLE,
    .autocommissioning = true,
    .poll_period           = DEFAULT_POLL_PERIOD,
    .default_child_timeout = DEFAULT_CHILD_TIMEOUT,
};

I was then able to find and connect the gateway as normal:

<info> app: Thread version   : OPENTHREAD/20180926-01143-g8a1992e2; NRF52840; Dec 10 2019 22:48:00
<info> app: Network name     : NordicOpenThread
<info> app: Thread interface has been enabled.
<info> app: 802.15.4 Channel : 11
<info> app: 802.15.4 PAN ID  : 0xABCD
<info> app: Radio mode       : rx-off-when-idle
<warning> app_timer: RTC instance already initialized.
<info> app: State changed! Flags: 0x011FD33D Current role: 1

<info> app: State change<info> app: MQTT-SN event: Client has found an active gateway.
<info> app: MQTT-SN event: Client connected.
<info> app: MQTT-SN event: Client registered topic.
<info> app: MQTT-SN event: Topic has been registered with ID: 1.
<info> app: MQTT-SN event: Gateway discovery procedure has finished.
<info> app: MQTT-SN event: Gateway discovery result: 0x0.
<info> app: MQTT-SN event: Client has successfully published content.
<info> app: MQTT-SN event: Client has successfully published content.

Best regards,
Jørgen

[rogerarchibald]

Thank you for the assistance Jørgen and Marjeris!

Thanks,

Roger