Using Wovyn Sensors

Connecting a Wovyn sensor to the Internet of Things using a Pico and KRL.

Opening up the sensor, we can see model, serial, and version numbers. The small black chip is the temperature sensor.

Step-by-step guide

To configure the sensor's endpoint, we must turn the sensor into a wifi hotspot and connect to it.

Before doing this, find and record the ip address your pico engine is running on, the port number, pico ECI (channel) for the incoming event from the Wovyn device, and the domain/type of the event you would like to send (e.g. wovyn/heartbeat). Use this information to create a Sky Event API URL

1 http://<yourIPaddress>:<yourPort>/sky/event/<yourECI>/<eventID>/<domain>/<type>

You can test this URL in your browser to ensure it connects to your pico and raises the right event.

Configuring the sensor to send the event:

  1. To turn the sensor into a hotspot, interrupt the power by disconnecting the power cable. After a few seconds, reapply power. As soon as you see the first blue LED flash (it will be a rapid flash), hold down the white button on the board. There will be a pause, then some rapid blue LED flashes for 3 seconds or so. After the rapid flashes end, release the button. The window to hold down the button after you reapply power is short, so be ready.

  2. Select the WiFi hotspot using your personal computer. In our case, its advertised name is Wovyn_2C2025. After a brief moment, the capture screen appears. See step 4 if it does not automatically appear.

  3. On some operating systems, the capture screen does not appear automatically, and you'll need to open a browser, navigate somewhere (doesn't matter where), and the capture will then open.

  4. If you click on the button "Configure WiFi", the device will scan for WiFi hotspots and present a list, from which you can select one. Select the network which the device should use to communicate to the Internet. If you know the SSID, you could instead choose the button "Configure WiFi (No Scan)", and enter the SSID manually. You will enter the Sky Event URL you created above as the Endpoint URI. You will see these prompts:

  5. Save the configuration. If you do not hit save, but rather hit cancel, then the device will remain as a hotspot for a little while and you may wonder why it is not sending any events.

  6. The device responds with this acknowledgement page. The page will close automatically after a few seconds.

  7. Of course the pico identified by the ECI will need a ruleset to receive the event. This is the KRL code that we used initially. 

    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ruleset post_test { meta { shares __testing } global { __testing = { "queries": [ { "name": "__testing" } ], "events": [ { "domain": "post", "type": "test", "attrs": [ "temp", "baro" ] } ] } } rule post_test { select when post test pre { never_used = event:attrs().klog("attrs") } } }

    The rule selected does nothing but log the event attributes. Notice that the ruleset shares a test harness which allows us to easily send a test event from the "Testing" tab of the "My Picos" page.

  8. We used the "Logging" tab to see what happens when the device sends an event. 
    Notice that several attributes are sent by the device. The first of these are "version", "eventDomain", "eventName", and "emitterGUID". The horizontal scrollbar indicates that there is much more. Capturing and re-formatting all of it, we see that the remaining attributes are named "genericThing", "specificThing", and "property". The following data structure is current as of 1/21/18.

    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 { "emitterGUID":"5CCF7F2BD537", "eventDomain":"wovyn.emitter", "eventName":"sensorHeartbeat", "genericThing":{ "typeId":"2.1.2", "typeName":"generic.simple.temperature", "healthPercent":56.89, "heartbeatSeconds":10, "data":{ "temperature":[ { "name":"ambient temperature", "transducerGUID":"28E3A5680900008D", "units":"degrees", "temperatureF":75.31, "temperatureC":24.06 } ] } }, "property":{ "name":"Wovyn_2BD537", "description":"Temp1000", "location":{ "description":"Timbuktu", "imageURL":"", "latitude":"16.77078", "longitude":"-3.00819" } }, "specificThing":{ "make":"Wovyn ESProto", "model":"Temp1000", "typeId":"", "typeName":"enterprise.wovyn.esproto.wtemp.1000", "thingGUID":"5CCF7F2BD537.1", "firmwareVersion":"Wovyn-WTEMP1000-1.14", "transducer":[ { "name":"Maxim DS18B20 Digital Thermometer", "transducerGUID":"28E3A5680900008D", "transducerType":"Maxim Integrated.DS18B20", "units":"degrees", "temperatureC":24.06 } ], "battery":{ "maximumVoltage":3.6, "minimumVoltage":2.7, "currentVoltage":3.21 } }, "version":2 }

  9. We also tried out the "Reset" option, which apparently forgets only the WiFi hotspot the device uses to send its heartbeat events, but retains the endpoint information.

  10. Finally, the "Info" button presents some internal information.