Minimized and with real time in the plots

main.go

@@ -12,6 +12,7 @@ import (
 )
 
 var dataFile *os.File
+var startTime time.Time
 
 type VoltageData struct {
 	Voltage float64 `json:"voltage"`
@@ -24,7 +25,7 @@ func initDataFile() {
 	}
 
 	// Generate a filename with timestamp
-	filename := filepath.Join("data", fmt.Sprintf("voltages_%s.txt", time.Now().Format("20060102_150405")))
+	filename := filepath.Join("data", fmt.Sprintf("voltages_%s.csv", time.Now().Format("20060102_150405")))
 	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
 	if err != nil {
 		log.Fatalf("Failed to open data file: %v", err)
@@ -32,6 +33,11 @@ func initDataFile() {
 
 	dataFile = file
 	log.Printf("Logging voltage data to %s\n", filename)
+
+	// Write CSV header
+	_, _ = dataFile.WriteString("time_s,voltage\n")
+
+	startTime = time.Now()
 }
 
 func handler(w http.ResponseWriter, r *http.Request) {
@@ -54,12 +60,15 @@ func handler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Print voltage to console
-	fmt.Println("Received voltage:", v.Voltage)
+	// Compute relative time
+	relTime := time.Since(startTime).Seconds()
 
-	// Append voltage number to file
+	// Print voltage to console
+	fmt.Printf("Received voltage: %f at time %.3f s\n", v.Voltage, relTime)
+
+	// Append CSV line to file
 	if dataFile != nil {
-		if _, err := dataFile.WriteString(fmt.Sprintf("%f\n", v.Voltage)); err != nil {
+		if _, err := dataFile.WriteString(fmt.Sprintf("%.3f,%.6f\n", relTime, v.Voltage)); err != nil {
 			log.Printf("Failed to write to file: %v", err)
 		}
 	}