diff --git a/Controller/ESPTempSender.ino b/Controller/ESPTempSender.ino
new file mode 100644
index 0000000..f8fd28d
--- /dev/null
+++ b/Controller/ESPTempSender.ino
@@ -0,0 +1,133 @@
+/* Read the temperature from a DS18b20 sensor
+ * from a ESP8266 NodeMCU
+ * 2021-06-06  Trs      Creation
+ * 2023-07-10  Trs,Jfs  Use deep sleep to reduce consumption, send value via UDP frame
+ */
+
+#include <DS18B20.h> // https://github.com/matmunk/DS18B20
+#include <ESP8266WiFi.h>
+//#include <WiFiClient.h>
+#include <WiFiUdp.h>
+#include <IPAddress.h>
+
+// Configuration
+static const uint8_t  D2   = 4; // ESP8266 -- do not forget to pullup signal to 3V3 with ~1 kOhm
+static const uint16_t DEEP_SLEEP_AFTER_S = 10;
+static const uint16_t SLEEP_FOR_S = 30 * 60; // 30 minutes
+static const uint16_t cSendMeasurementInterval = 2000;
+static const char SSID[] = "<YOUR SSID>";
+static const char PASS[] = "<YOUR PASSWORD>";
+
+static const char     cTargetIP[] = "<SERVER ADDRESS>";
+static const uint16_t cTargetPort = 14000;
+
+static const char cUDPPacketStart[] = "{\"sender\":\"ESPTempSender\",\"compile-date\":\"" __DATE__ "\",\"temperature\":\"";
+static const char cUDPPacketEnd[] = "\"}";
+
+// working variables
+DS18B20 ds(D2);
+uint8_t selected;
+int32_t gSleepTime;
+
+ESP8266WiFiSTAClass wifiMulti;
+WiFiUDP UDP;
+IPAddress gTarget;
+
+
+void setup()
+{
+  // --- Preparation and Info
+  Serial.begin(115200);
+  Serial.setTimeout(2000);
+  // Wait for serial to initialize.
+  while(!Serial) { }
+
+  Serial.print("\r\n" __DATE__);
+  Serial.println(" ESP Temperature sender. Sender on D2(4), Deep-sleep with reset from D0 to RST");
+
+  // --- Init temperature sensor
+  selected = ds.selectNext();
+  if (selected) {
+    Serial.println("Sensor found");
+  } else {
+    Serial.println("Sensor not found, no values will be reported!");
+  }
+
+  // --- Connect to WiFi network to send UDP frames to the server
+  WiFi.begin(SSID, PASS);
+  Serial.print("Connecting to ");
+  Serial.print(SSID);
+  int i = 0;
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(250);
+    Serial.print('.');
+  }
+  Serial.println('\n');
+  Serial.print("Connected to ");
+  Serial.println(WiFi.SSID());              // Tell us what network we're connected to
+  Serial.print("IP address:\t");
+  Serial.println(WiFi.localIP());           // Send the IP address of the ESP8266 to the computer
+
+  gTarget.fromString(cTargetIP);
+  Serial.print("Sending to:\t");
+  Serial.print(gTarget);
+  Serial.print(" Port: ");
+  Serial.println(cTargetPort);
+
+  // ---
+  // System will go to deep sleep after this time
+  gSleepTime = millis() + DEEP_SLEEP_AFTER_S * 1000;
+}
+
+// ---
+void UDPSendTemperature(float temperature)
+{
+  UDP.beginPacket(gTarget, cTargetPort);
+  UDP.write(cUDPPacketStart, sizeof(cUDPPacketStart) - 1);
+  char tempBuff[10];
+  auto count = snprintf(tempBuff, 9, "%.1f", temperature);
+  UDP.write(tempBuff, count);
+  UDP.write(cUDPPacketEnd, sizeof(cUDPPacketEnd) - 1);
+
+  // close packet and send it
+  auto result = UDP.endPacket();
+
+  // For documentation purposes, also write the data to serial port
+  Serial.print("Sent with result ");
+  Serial.print(result);
+  Serial.print(": ");
+  Serial.print(cUDPPacketStart);
+  Serial.print(tempBuff);
+  Serial.println(cUDPPacketEnd);
+}
+
+void loop()
+{
+  if (selected)
+  {
+    float fTemp = ds.getTempC();
+    Serial.print("Temperature is ");
+    Serial.print(fTemp);
+    Serial.println(" C");
+    UDPSendTemperature(fTemp);
+  } else {
+    Serial.println("Device not found!");
+  }
+
+  int32_t diff = gSleepTime - millis();
+  if (diff > 0)
+  {
+    Serial.print("Time/ms until sleep: ");
+    Serial.println(diff);
+  } else
+  {
+    Serial.print("Going to deep sleep for ");
+    Serial.print(SLEEP_FOR_S);
+    Serial.println(" seconds ...");
+    ESP.deepSleep(SLEEP_FOR_S * 1e6); // in us
+
+    // Since a reset is executed, the program will start over with the setup() function
+  }
+
+  delay(cSendMeasurementInterval);
+}
diff --git a/README.md b/README.md
index 62b4985..8242ff0 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,25 @@
-# WiFi-Temperature-Sender
+# A rather simple WiFi temperature sender
 
-Use a micro-controller with WiFi, e.g. a NodeMCU V2 or V3, to send temperature values read from a DS18B20 sensor to a server.
\ No newline at end of file
+Use a micro-controller with WiFi, e.g. a NodeMCU V2 or V3, to send temperature values read from a DS18B20 sensor to a server.
+
+## Concept
+
+* The sender is a controller with WiFi that can read values from a temperature
+sensor.
+* Values are sent to a server with hard-coded IP address.
+* The controller is configured to go to "deep sleep" after sending values.
+* The wakeup feature of the controller shall be used to reactivate it after
+about 30 min. Note that not all controller boards have such a feature,
+e.g. the very simple ESP-01 boards to not make the wakeup pin accessible.
+* Using deep sleep, it should be possible to run the sender for several days
+or even weeks with a simple USB power bank.<br/>
+Of course, a more sophisticated powering system would be nice.
+* The messages are a simple UDP packet containing a JSON structure.
+* The server listens at a pre-configured port and can process the
+JSON structure.
+* One server implementation is a Python script that collects the reported
+values in a CSV file.
+* The CSV file can be processed into a simple static web page for display in
+the local network.
+
+**WORK IN PROGRESS**
\ No newline at end of file