UD-CO2S にシリアル接続してデータを JSON ファイルに上書きし続けるスクリプト を go でサーバにしたやつ

ud_cos2_server.go

package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/signal"
	"regexp"
	"strconv"
	"syscall"
	"time"

	"github.com/tarm/serial"
)

type SensorData struct {
	Time        int64   `json:"time"`
	CO2PPM      int     `json:"co2ppm"`
	Humidity    float64 `json:"humidity"`
	Temperature float64 `json:"temperature"`
}

func (s SensorData) toString() string {
	return fmt.Sprintf("Time: %d, CO2PPM: %d, Humidity: %.2f, Temperature: %.2f", s.Time, s.CO2PPM, s.Humidity, s.Temperature)
}

var currentData SensorData
var running = true

func main() {
	port := flag.String("p", "8080", "Port number")
	flag.Parse()

	go startSerial("/dev/ttyACM0")
	http.HandleFunc("/sensor.json", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(currentData)
	})

	go http.ListenAndServe(":"+*port, nil)

	// Set up signal handling
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGHUP)
	go func() {
		for {
			sig := <-sigChan
			switch sig {
			case syscall.SIGHUP:
				fmt.Println(sig.String() + " signal received, stopping...")
				running = false
				return
			}
		}
	}()

	// Wait for the signal handler to stop the program
	for running {
		time.Sleep(1 * time.Second)
	}
	fmt.Println("Program stopped")
}

func startSerial(dev string) {
	cfg := &serial.Config{Name: dev, Baud: 115200, ReadTimeout: time.Second * 6}
	s, err := serial.OpenPort(cfg)
	if err != nil {
		fmt.Println("Error opening serial port:", err)
		return
	}
	defer s.Close()

	_, err = s.Write([]byte("STA\r\n"))
	if err != nil {
		fmt.Println("Error writing to serial port:", err)
		return
	}
	buf := make([]byte, 128)
	_, err = s.Read(buf)
	if err != nil {
		fmt.Println("Error reading from serial port:", err)
		return
	}

	regex := regexp.MustCompile(`CO2=(?P<co2>\d+),HUM=(?P<hum>\d+\.\d+),TMP=(?P<tmp>-?\d+\.\d+)`)
	for running {
		n, err := s.Read(buf)
		if err != nil {
			if err != io.EOF {
				fmt.Println("Error reading from serial port:", err)
			}
			break
		}
		str := string(buf[:n])
		matches := regex.FindStringSubmatch(str)
		if matches != nil {
			co2, _ := strconv.Atoi(matches[1])
			hum, _ := strconv.ParseFloat(matches[2], 64)
			tmp, _ := strconv.ParseFloat(matches[3], 64)
			currentData = SensorData{
				Time:        time.Now().Unix(),
				CO2PPM:      co2,
				Humidity:    hum,
				Temperature: tmp,
			}

			fmt.Println(currentData.toString())
		}
	}
	_, err = s.Write([]byte("STP\r\n"))
	if err != nil {
		fmt.Println("Error writing to serial port:", err)
	}
}