dht_sensor.go

package main

import (
        "bytes"
        "encoding/json"
        "fmt"
        "io/ioutil"
        "log"
        "net/http"
        "os"
        "time"
        "github.com/d2r2/go-dht"
)

var (
        BaseURL = "http://api-m2x.att.com"
)

// Value is a current sensor reading
type Value struct {
        Time  time.Time `json:"timestamp"`
        Value string    `json:"value"`
}

// Sensor is a structure which contains multiple temperature and humidity values
type Sensor struct {
        Temperature []Value `json:"Temperature"`
        Humidity    []Value `json:"Humidity"`
}

// SensorWrap is a wrapper for the data structure
type sensorwrap struct {
        time   time.time `json:"timestamp"`
        sensor `json:"values"`
}
func main() {
        // read dht11 sensor data from pin 4, retrying 10 times in case of failure.
        // you may enable "boost gpio performance" parameter, if your device is old
        // as raspberry pi 1 (this will require root privileges). you can switch off
        // "boost gpio performance" parameter for old devices, but it may increase
        // retry attempts. play with this parameter.
        temperature, humidity, _, err := dht.readdhtxxwithretry(dht.dht11, 7, true, 10)
        if err != nil {
                log.fatal(err)
        }

        current := sensorwrap{
                time: time.now(),
                sensor: sensor{
                        temperature: []value{{time.now(), fmt.sprintf("%.6f", temperature)}},
                        humidity:    []value{{time.now(), fmt.sprintf("%.6f", humidity)}},
                },
        }

        currentjson, err := json.marshal(current)
        if err != nil {
                fmt.println("could not marshal the data", err)
        }

        // request part begins
        url := fmt.sprintf("%s/v2/devices/%s/updates", baseurl, os.getenv("m2x_device_id"))

        client := &http.client{}

        req, err := http.newrequest("post", url, bytes.newreader(currentjson))
        if err != nil {
                log.fatal(err)
        }
        req.header.add("x-m2x-key", os.getenv("m2x_key"))
        req.header.add("content-type", "application/json")

        resp, err := client.do(req)
        if err != nil {
                log.fatal(err)
        }
        defer resp.body.close()

        // response output
        fmt.println("status:", resp.status)
        fmt.println("headers:", resp.header)
        body, _ := ioutil.readall(resp.body)
        fmt.println("body:", string(body))

        fmt.println(currentjson)
}

sensors

# Needs root permission to read the GPIO

M2X_KEY=add-key-here
M2X_DEVICE_ID=add-key-here

*/20 * * * * root /home/pi/go/src/github.com/riston/sensors/dht_sensor >> /var/log/dht-sensor.log 2>&1