t2-rest-relay-climate

REST + Linked Data interface for a Tessel 2 with a climate and relay module. So this gives you REST + Linked Data access to a temperature sensor, a humidity sensor, and two power switches.

Set-up recipe

• Require:
  • NodeJS
• Buy:
  • A Tessel 2
  • A climate module and
  • A relay module.
• Plug:
  • The relay module to Tessel's port A, and
  • The climate module to port B.
  • Attach something to the relay module (may require some wire cutting and soldering)
  • USB cable from your computer to the Tessel
• Install:
  • The Tessel CLI: npm i -g t2-cli
  • The dependencies from this repo: npm i
  • The code from this repo onto the Tessel: t2 push .
• Configure:
  • The network
    • Connect the Tessel to your Ethernet or WiFi, then give the Tessel a certain IP or hostname, or
    • Make the Tessel open a WiFi access point, eg. t2 wifi -n t2-rest-relay-climate (add security, and enable the access point), and connect to the access point
  • The Tessel
    • Give the Tessel a name, eg. t2 rename t2-rest-relay-climate (the name is used, eg. if the Tessel's access point does DNS resolution, see below)
• Unplug the Tessel, give the Tessel USB power, and wait for it to boot.

Implementation details

Serves RDF in RDF/XML, Turtle, JSON-LD, ... as Linked Data on a REST interface. Built on the Express and RDF-Ext frameworks. Describes the Tessel 2 using the following vocabularies: SOSA/SSN, SAREF, QUDT, FOAF (see below).

You can:

(The examples use t2-rest-relay-climate.lan as the Tessel's hostname)

Access the root resource:

$ curl -Haccept:text/turtle http://t2-rest-relay-climate.lan/

yields:

@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix sosa: <http://www.w3.org/ns/sosa/> .

<#t2> 
    a sosa:Platform ;
    sosa:hosts <climate/#module>, <relay/#module>;
    foaf:isPrimaryTopicOf <>.

Explore what is there following ssn:hosts links:

Find sensors and actuators, for instance:

Access the temperature sensor:

$ curl -Haccept:text/turtle http://t2-rest-relay-climate.lan/climate/temperature 

yields:

@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix ssn: <http://www.w3.org/ns/ssn/> .
@prefix qudt: <http://qudt.org/schema/qudt/> .
@prefix saref: <https://w3id.org/saref#> .

<#sensor>
    a saref:TemperatureSensor ;
    ssn:hasProperty <#value> .

<#value>
    qudt:quantityValue [
        qudt:numericValue 27.88 ;
        qudt:unit <http://qudt.org/vocab/unit/DEG_C>
    ] ;
    foaf:isPrimaryTopicOf <> .

Access one of the relays:

$ curl -Haccept:text/turtle http://t2-rest-relay-climate.lan/relay/1

yields:

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix sosa: <http://www.w3.org/ns/sosa/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix saref: <https://w3id.org/saref#> .

<#relay>
    a saref:Switch ;
    sosa:hasProperty <#state> .

<#state>
    a sosa:ActuatableProperty, sosa:ObservableProperty ;
    rdf:value saref:Off ;
    foaf:isPrimaryTopicOf <> .

Turn on and off a relay:

$ curl -X PUT http://t2-rest-relay-climate.lan/relay/1 -Hcontent-type:text/turtle --data-binary " <http://tessel-ip-or-hostname/relay/1#state> <http://www.w3.org/1999/02/22-rdf-syntax-ns#value> <https://w3id.org/saref#Off> . "

Status

First rough implementation.