MQTT Subscribe Deep Sleep / ESP32 / FreeRTOS

The goal is to receive messages over MQTT in an IoT device that comes out of deep sleep periodically. The exact same considerations exist for OTA update as for any other parameter update. In my case, ultimately, I want to use this for both.

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Progress

It runs

The device wakes for about 15 seconds. If during that time, I publish a bunch of messages to the relevant topic, the message arrived successfully. Inside the AWS console I can publish to :

$aws/things/<device-name>/shadow/update/delta    {      "state":{          "desired":{              "output":true          }      }  }  

And the delta callback function runs for 'output'. Great but no practical use to anyone.

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IoT Job

I created a custom AWS IoT job in the console in an effort to overcome the problem. My thinking was that it might retain the message to ensure delivery. I've been running the job for the past half hour but so far nothing has come through. It had a 20 timeout but is still stuck in queued, not even in progress yet... So, there is clearly a flaw in this approach.

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AWS CLI test

Just for completeness, I've attempted to fire off the MQTT message from the console. It has the benefit that you can specify the QOS, (in theory) ensuring that it gets delivered at least once.

aws iot-data publish --topic "$aws/things/<device-name>/shadow/update/delta" --qos 1 --payload file://Downloads/outputTrue.json --cli-binary-format raw-in-base64-out  

But oddly this didn't seem to work at all. I didn't see the message arrive at the broker at all: subscribing in the console test.

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https://stackoverflow.com/questions/65768286/mqtt-subscribe-deep-sleep-esp32-freertos January 18, 2021 at 11:01AM