92 lines
4.2 KiB
Markdown
92 lines
4.2 KiB
Markdown
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# CC13xx/CC26xx Very Sleepy Demo
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This example demonstrates a way of deploying a very low-consuming, very sleepy
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node. The node has two modes of operation:
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* Normal: ContikiMAC duty-cycles the radio as usual. The node is reachable.
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* Very Sleepy: Radio cycling mostly off, except when we need to perform network
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maintenance tasks. In this mode, the node is unreachable for most of the time.
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The node will operate in RPL leaf mode. This means that it will be reachable
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downwards, but it will not advertise the DODAG and it will not participate in
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routing.
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After booting, the node will enter "normal" mode.
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The node exposes an OBSERVEable CoAP resource. It will notify subscribers with
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a new value for this resource every `interval` seconds. It will then stay in
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normal mode for `duration` seconds. During this time window, it will be
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reachable over the network in order to e.g. receive a new configuration.
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When this time window expires, the node will switch back to very sleepy mode.
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This will only happen if very sleepy mode has been enabled by setting `mode=1`
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as per the instructions below.
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When the node is duty-cycling the radio, either because it is in normal mode or
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because network maintenance is taking place, it will keep its green LED on thus
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providing an indication that it is reachable.
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A normal mode stint can be manually triggered by pressing the left button.
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## Requirements
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To run this example you will need:
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* A border router operating with the same RDC, same channel, same radio mode
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(e.g. IEEE or sub-ghz), same PAN ID. Alternatively, you can
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use [6lbr](https://github.com/cetic/6lbr) with a suitable slip-radio.
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* The [Copper (Cu)](https://addons.mozilla.org/en-US/firefox/addon/copper-270430/)
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addon for Firefox
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## Configuration
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To configure the node, send a CoAP POST message to the `very_sleepy_config`
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resource. The POST message's payload must specify _at least one_ of:
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* `mode=0|1`: Send `mode=1` to enable very sleepy mode, `mode=0` to disable it.
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* `interval=n` where `n` is the number of seconds between two consecutive normal
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mode periods. This interval also dictates the OBSERVEr notification period.
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* `duration=n` where `n` is the number of seconds that the node will stay in
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normal mode before dropping to very sleepy mode. This value is only relevant
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if `mode==1`.
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A POST request must contain at least one of the above, but they are otherwise
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all optional. So, for example, a POST may simply specify `interval=n`. To send
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multiple values, delimit them with `&`. So you can send something like
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`mode=1&interval=60&duration=20`
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The current running configuration can be retrieved by sending a GET request to
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the same CoAP resource.
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## Running the example
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* Deploy your border router or 6lbr
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* Turn on the very sleepy node.
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* Fire up the Copper addon
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* Select `.well-known/core` and hit `GET`
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* Configure very sleepy operation:
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* Select the `very_sleepy_config` resource
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* In the `Outgoing` pane, type your POST payload as per the instructions
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above. For example, you can type: `mode=1&interval=30&duration=10`
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* Hit `POST`
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* Select the `sen/readings` resource and hit `OBSERVE`
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## Caveats
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If you click on a resource in the Copper resources tree while you are observing
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a different resource, the OBSERVEr for the latter will be stopped without
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notifying the CoAP server. This will result in the server sending out OBSERVE
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notifications that will be responded to with port unreachable ICMPv6 messages.
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This will continue for quite a while, until the server detects that the
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OBSERVEr has been lost (a test currently performed once every 20 notifications).
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In order to prevent this from happening, hit the "Cancel" button for the
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OBSERVE before switching views to a different resource. This will unregister
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the observer.
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In very sleepy mode, the radio is not truly always off. The contiki core needs
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to perform other periodic tasks in order to maintain network connectivity. For
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that reason, this example will allow the radio to turn on periodically even
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while in very sleepy mode. Thus, you may see that the node becomes briefly
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reachable every now and then. However, do not count on those periods of
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reachability to perform any tasks, as they will be brief and will be disrupted
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without warning.
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