Enable NTP updates on Arduino

arduino/eeprom_prog/eeprom_prog.ino

@@ -9,7 +9,7 @@ const char serial[] = "abcd1234";
 
 struct netConfig {
   IPAddress address;
-  int port;
+  unsigned int port;
 };
 
 netConfig config = {

arduino/tempLightSensor/tempLightSensor.ino

@@ -1,23 +1,31 @@
 #include <EEPROM.h>
 #include <Ethernet.h>
+#include <EthernetUdp.h>
+#include <NTPClient.h>
 #include <ArduinoJson.h>
 
 #define DEBUG_TO_SERIAL 1
+#define USE_INTERNAL_NTP 0 // use default ntp server or the internal one
 #define AREF_VOLTAGE 3.3
 
-const String serverName = "sensor.server.domain";
+// const String serverName = "sensor.server.domain";
 
-const size_t capacity = JSON_OBJECT_SIZE(1) + 2*JSON_OBJECT_SIZE(6);
-DynamicJsonDocument doc(capacity);
-JsonObject payload = doc.createNestedObject("payload");
+const size_t capacity = JSON_OBJECT_SIZE(2) + 2 * JSON_OBJECT_SIZE(3) + 110;
+
+DynamicJsonDocument json(capacity);
+JsonObject payload = json.createNestedObject("payload");
 JsonObject temp = payload.createNestedObject("temperature");
 
+unsigned int counter = 0;
 int tempPin = A0;
 int photocellPin = A1;
 
+EthernetUDP ntpUDP;
+NTPClient timeClient(ntpUDP);
+
 struct netConfig {
   IPAddress address;
-  int port;
+  unsigned int port;
 };
 netConfig config;
 
@@ -26,37 +34,32 @@ const int postDelay = 10 * 1000;
 
 void setup(void) {
   Serial.begin(9600);
-  
+
   analogReference(EXTERNAL);
 
   byte mac[6];
   char serial[9];
-  
+
   int eeAddress = 0;
 
   EEPROM.get(eeAddress, mac);
   eeAddress += sizeof(mac);
   EEPROM.get(eeAddress, serial);
   eeAddress += sizeof(serial);
-  
-  Serial.println("Initialize Ethernet with DHCP:");
+
   if (Ethernet.begin(mac) == 0) {
-    Serial.println("Failed to configure Ethernet using DHCP");
     if (Ethernet.hardwareStatus() == EthernetNoHardware) {
-      Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
-    } else if (Ethernet.linkStatus() == LinkOFF) {
-      Serial.println("Ethernet cable is not connected.");
+      Serial.println("ERROR: ethernet shield was not found.");
     }
-    // no point in carrying on, so do nothing forevermore:
     while (true) {
       delay(1);
     }
   }
   EEPROM.get(eeAddress, config);
-  
+
   Serial.print("IoT #");
   Serial.print(serial);
-  Serial.println(" started at address:");
+  Serial.println(" at address:");
   Serial.println(Ethernet.localIP());
   Serial.println();
   Serial.println("Connecting to:");
@@ -64,43 +67,66 @@ void setup(void) {
   Serial.print(":");
   Serial.println(config.port);
 
-  doc["device"] = serial;  // FIXME
-  payload["id"] = serverName;
+#if USE_INTERNAL_NTP
+  timeClient.setPoolServerIP(config.address);
+#endif
+  timeClient.begin();
+  timeClient.update();
+
+#if DEBUG_TO_SERIAL
+  Serial.println("DEBUG: clock updated via NTP.");
+#endif
+
+  json["device"] = 1;  // FIXME
+  // payload["id"] = serverName;
 }
 
 void loop(void) {
-  
-  int photocellReading = analogRead(photocellPin);
-  int tempReading = analogRead(tempPin);
+
+  unsigned int photocellReading = analogRead(photocellPin);
+  unsigned int tempReading = analogRead(tempPin);
 
   float tempVoltage = tempReading * AREF_VOLTAGE / 1024.0;
   float tempC = (tempVoltage - 0.5) * 100 ;
 
+  json["time"] = timeClient.getEpochTime();
   payload["light"] = photocellReading;
 
   temp["celsius"] = tempC;
   temp["raw"] = tempReading;
   temp["volts"] = tempVoltage;
-  
+
   if (EthernetClient client = client.connect(config.address, config.port)) {
     client.print("POST ");
     client.print(URL);
     client.println(" HTTP/1.1");
     client.print("Host: ");
-    printAddr(config.address, &client);
+    client.print(config.address);
     client.print(":");
     client.println(config.port);
     client.println("Content-Type: application/json");
     client.print("Content-Length: ");
-    client.println(measureJsonPretty(doc));
+    client.println(measureJsonPretty(json));
     client.println("Connection: close");
     client.println();
-    serializeJson(doc, client);
+    serializeJson(json, client);
     client.stop();
-    
-    #if DEBUG_TO_SERIAL
-    serializeJsonPretty(doc, Serial);
-    #endif
+
+#if DEBUG_TO_SERIAL
+    Serial.println("DEBUG: >>>");
+    serializeJsonPretty(json, Serial);
+    Serial.println("\n<<<");
+#endif
+  }
+
+  if (counter == 6 * 120) { // Update clock every 6 times * 10 sec * 120 minutes = 2 hrs
+    timeClient.update();
+    counter = 0;
+#if DEBUG_TO_SERIAL
+    Serial.println("DEBUG: clock updated via NTP.");
+#endif
+  } else {
+    counter++;
   }
 
   delay(postDelay);

docker/ntpd/chrony.conf

@@ -1,3 +1,4 @@
 pool pool.ntp.org iburst
 initstepslew 10 pool.ntp.org
 driftfile /var/lib/chrony/chrony.drift
+allow all