MQTT keepalive and reset devices on master boot

close #1

master/master.ino

@@ -7,6 +7,7 @@
 
 // needs global define
 #define DATA_STOP_BYTE 0x00
+#define DATA_RESET_BYTE 0xFF
 #define HEADING_TRIGGER_BIT 1
 #define HEADING_HIGH_BIT 2
 #define ALTITUDE_TRIGGER_BIT 4
@@ -14,15 +15,17 @@
 
 #define HEADING_SIM_UP "sim/autopilot/heading_up"
 #define HEADING_SIM_DOWN "sim/autopilot/heading_down"
-// XXX: double check altitude values
 #define ALTITUDE_SIM_UP "sim/autopilot/altitude_up"
 #define ALTITUDE_SIM_DOWN "sim/autopilot/altitude_down"
 #define AIRPSEED_SIM_UP "sim/autopilot/airspeed_up"
 #define AIRSPEED_SIM_DOWN "sim/autopilot/airspeed_down"
 
 #define MQTT_SIM_COMMAND_TOPIC "/xplane/meta/cmnd"
+#define MQTT_SIM_DEVICE_TOPIC "/xplane/meta/device"
 #define MQTT_SIM_VALUE_TOPIC "/xplane/rref/#"
 
+#define MQTT_KEEPALIVE_INTERVAL_MS 15000
+
 struct device {
   byte address;
   String name;
@@ -41,7 +44,9 @@ int        port     = 1883;
 const char topic[]  = MQTT_SIM_VALUE_TOPIC;
 
 EthernetClient client;
+char localIP[16];
 MqttClient mqttClient(client);
+unsigned long mqttLastKeepAlive = millis();
 
 void onMqttMessage(int messageSize) {
 //  // we received a message, print out the topic and contents
@@ -77,7 +82,8 @@ void setup() {
     while (1);
   }
   // print your local IP address:
-  Serial.println(Ethernet.localIP());
+  sprintf(localIP, "%d.%d.%d.%d", Ethernet.localIP()[0], Ethernet.localIP()[1], Ethernet.localIP()[2], Ethernet.localIP()[3]);
+  Serial.println(localIP);
 
   // MQTT auth
   mqttClient.setUsernamePassword(MQTT_USER, MQTT_PASS);
@@ -95,6 +101,7 @@ void setup() {
   // subscribe to MQTT topic
   mqttClient.onMessage(onMqttMessage);
   mqttClient.subscribe(topic);
+  mqttClient.setKeepAliveInterval(10 * 1000L);
 
   // start I2C
   Wire.begin();
@@ -104,6 +111,13 @@ void setup() {
   digitalWrite(LED_TX, HIGH);
   pinMode(LED_RX, OUTPUT);
   digitalWrite(LED_RX, HIGH);
+
+  // initialize devices
+  for (int i = 0; i < numDevices; i++) {
+    Wire.beginTransmission(devices[i].address);
+    Wire.write(DATA_RESET_BYTE);
+    Wire.endTransmission(devices[i].address);
+  }
 }
 
 void loop() {
@@ -134,4 +148,11 @@ void loop() {
       }
     }
   }
+
+  // transmit MQTT keepalive message if MQTT_KEEPALIVE_INTERVAL_MS is reached
+  // or millis() is wrapping to 0
+  if (mqttLastKeepAlive + MQTT_KEEPALIVE_INTERVAL_MS < millis() || mqttLastKeepAlive > millis()) {
+    sendMqttMessage(MQTT_SIM_DEVICE_TOPIC, localIP);
+    mqttLastKeepAlive = millis();
+  }
 }

rotator/rotator.ino

@@ -12,6 +12,7 @@
 
 // needs global define
 #define DATA_STOP_BYTE 0x00
+#define DATA_RESET_BYTE 0xFF
 #define ROTATOR1_TRIGGER_BIT 1
 #define ROTATOR1_HIGH_BIT 2
 #define ROTATOR2_TRIGGER_BIT 4
@@ -95,6 +96,17 @@ void i2cRequest() {
   }
 }
 
+void i2cReceive(int bytes) {
+  for (int i = 0; i < bytes && Wire.available(); i++) {
+    byte data = Wire.read();
+    if (data == DATA_RESET_BYTE) {
+      writerPos = readerPos = 0;
+    } else {
+      // nothing else yet implemented
+    }
+  }
+}
+
 uint8_t address = 0;
 void setup() {
   Serial.begin(115200);
@@ -120,6 +132,7 @@ void setup() {
 
   Wire.begin(address);
   Wire.onRequest(i2cRequest);
+  Wire.onReceive(i2cReceive);
 }
 
 void loop() {