initial

.gitignore

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+.idea
+*.log

README.md

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+# Software for CO2 Monitor
+
+based on https://github.com/dmage/co2mon, more suitable for cron job to send data over MQTT
+
+
+## See also
+  * [ZyAura ZG01C Module Manual](http://www.zyaura.com/support/manual/pdf/ZyAura_CO2_Monitor_ZG01C_Module_ApplicationNote_141120.pdf)
+  * [RevSpace CO2 Meter Hacking](https://revspace.nl/CO2MeterHacking)
+  * [Photos of the device and the circuit board](http://habrahabr.ru/company/masterkit/blog/248403/)
+

go.mod

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+module co2mon
+
+go 1.14
+
+require (
+	github.com/eclipse/paho.mqtt.golang v1.2.0
+	github.com/karalabe/hid v1.0.0
+	golang.org/x/net v0.0.0-20200625001655-4c5254603344 // indirect
+)

go.sum

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+github.com/eclipse/paho.mqtt.golang v1.2.0 h1:1F8mhG9+aO5/xpdtFkW4SxOJB67ukuDC3t2y2qayIX0=
+github.com/eclipse/paho.mqtt.golang v1.2.0/go.mod h1:H9keYFcgq3Qr5OUJm/JZI/i6U7joQ8SYLhZwfeOo6Ts=
+github.com/karalabe/hid v1.0.0 h1:+/CIMNXhSU/zIJgnIvBD2nKHxS/bnRHhhs9xBryLpPo=
+github.com/karalabe/hid v1.0.0/go.mod h1:Vr51f8rUOLYrfrWDFlV12GGQgM5AT8sVh+2fY4MPeu8=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20200625001655-4c5254603344 h1:vGXIOMxbNfDTk/aXCmfdLgkrSV+Z2tcbze+pEc3v5W4=
+golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

main.go

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+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"time"
+
+	MQTT "github.com/eclipse/paho.mqtt.golang"
+	"github.com/karalabe/hid"
+)
+
+var (
+	temperature float32
+	co2         uint16
+)
+
+func getData(dev *hid.Device) error {
+	buf := make([]byte, 8)
+
+	i, err := dev.Read(buf)
+	if err != nil {
+		return err
+	}
+
+	if i != len(buf) {
+		return errors.New("wrong read bug size")
+	}
+
+	decode(buf)
+	return nil
+}
+
+func decode(buf []byte) {
+	res := make([]byte, 8)
+
+	var c byte
+	for _, n := range [][]int{{0, 2}, {1, 4}, {3, 7}, {5, 6}} {
+		c = buf[n[0]]
+		buf[n[0]] = buf[n[1]]
+		buf[n[1]] = c
+	}
+
+	var tmp = buf[7] << 5
+	res[7] = (buf[6] << 5) | (buf[7] >> 3)
+	res[6] = (buf[5] << 5) | (buf[6] >> 3)
+	res[5] = (buf[4] << 5) | (buf[5] >> 3)
+	res[4] = (buf[3] << 5) | (buf[4] >> 3)
+	res[3] = (buf[2] << 5) | (buf[3] >> 3)
+	res[2] = (buf[1] << 5) | (buf[2] >> 3)
+	res[1] = (buf[0] << 5) | (buf[1] >> 3)
+	res[0] = tmp | (buf[0] >> 3)
+
+	var magicWord = []byte("Htemp99e")
+
+	for i := 0; i < 8; i++ {
+		res[i] -= (magicWord[i] << 4) | (magicWord[i] >> 4)
+	}
+
+	if res[3] != res[0]+res[1]+res[2] {
+		return
+	}
+
+	var w uint16
+	w = uint16(res[1])*256 + uint16(res[2])
+
+	switch res[0] {
+	case 0x42:
+		temperature = float32(w)*0.0625 - 273.15
+	case 0x50:
+		co2 = w
+	}
+}
+
+func sendMqtt(server, topic, user, password string) error {
+	opts := MQTT.NewClientOptions()
+	opts.AddBroker(server)
+	opts.SetClientID("mqtt-go-sender")
+	opts.SetUsername(user)
+	opts.SetPassword(password)
+
+	client := MQTT.NewClient(opts)
+	if token := client.Connect(); token.Wait() && token.Error() != nil {
+		return token.Error()
+	}
+
+	token := client.Publish(topic+"/temperature", 0, false, fmt.Sprintf("%.2f", temperature))
+	token.Wait()
+	token = client.Publish(topic+"/co2", 0, false, fmt.Sprintf("%d", co2))
+	token.Wait()
+
+	client.Disconnect(250)
+	return nil
+}
+
+func main() {
+	server := flag.String("server", "", "The broker URI. ex: tcp://192.168.0.1:1883")
+	topic := flag.String("topic", "dadget/room", "Base topic to send to")
+	user := flag.String("user", "", "The User (optional)")
+	password := flag.String("password", "", "The password (optional)")
+
+	flag.Parse()
+
+	devs := hid.Enumerate(0x04d9, 0xa052)
+	if len(devs) == 0 {
+		fmt.Println("device not found")
+		os.Exit(1)
+	}
+
+	dev, err := devs[0].Open()
+	if err != nil {
+		fmt.Printf("can't open device - %v\n", err)
+		os.Exit(1)
+	}
+
+	time.AfterFunc(time.Second*30, func() {
+		println("timeout...")
+		os.Exit(2)
+	})
+
+	for temperature == 0 || co2 == 0 {
+		if err := getData(dev); err != nil {
+			fmt.Printf("error: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	fmt.Printf("temp: %.2f\nco2: %d\n", temperature, co2)
+
+	if *server != "" {
+		if err := sendMqtt(*server, *topic, *user, *password); err != nil {
+			fmt.Printf("error: %v\n", err)
+		}
+	}
+}