Implement XML reading output and update timestamp handling in sensor loop

example.xml

@@ -0,0 +1,8 @@
+<reading time="10" id="SHT40">
+    <temp unit="C">
+        23.45
+    </temp>
+    <humidity unit="%">
+        48.12
+    </humidity>
+</reading>

src/main.cpp

@@ -2,10 +2,13 @@
 #include <Adafruit_SHT4x.h>
 
 Adafruit_SHT4x sht4 = Adafruit_SHT4x();
+uint32_t timestamp = millis();
+
+void sendReadingXML(uint32_t timestamp, float temperature, float humidity, const char *id);
 
 void setup()
 {
-  Serial.begin(115200); // zacni seriovou komunikaci s baudrate 115200
+  Serial.begin(115200); // zacni seriovou komunikaci s baudrate 9600
   Serial.println("UART OK");
 
   pinMode(LED_BUILTIN, OUTPUT); // nastav ledku na desce jako vystup
@@ -28,17 +31,32 @@ void loop()
 {
   sensors_event_t humidity, temp;
 
-  uint32_t timestamp = millis();
   sht4.getEvent(&humidity, &temp);  // cteni ze senzoru
-  timestamp = millis() - timestamp; // ziskani delky cteni ze senzoru
+  timestamp = millis(); // pocet milisekund od spusteni procesoru
 
-  Serial.print("temp= ");
+  sendReadingXML(timestamp, temp.temperature, humidity.relative_humidity, "SHT40");
-  Serial.print(temp.temperature);
-  Serial.print(" humidity=");
-  Serial.println(humidity.relative_humidity);
 
   digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
   delay(250);                      // wait for a second
   digitalWrite(LED_BUILTIN, LOW);  // turn the LED off by making the voltage LOW
   delay(250);                      // wait for a second
 }
+
+void sendReadingXML(uint32_t timestamp, float temperature, float humidity, const char *id)
+{
+  Serial.print("<reading time=\"");
+  Serial.print(timestamp);
+  Serial.print("\" id=\"");
+  Serial.print(id);
+  Serial.println("\">");
+
+  Serial.print("    <temp unit=\"C\">");
+  Serial.print(temperature, 2);
+  Serial.println("</temp>");
+
+  Serial.print("    <humidity unit=\"%\">");
+  Serial.print(humidity, 2);
+  Serial.println("</humidity>");
+
+  Serial.println("</reading>");
+}