MQTT Client example program. Ethernet connection is via an ENC28J60 module.
Dependencies: UIPEthernet MQTTClient
main.cpp
- Committer:
- hudakz
- Date:
- 2015-03-21
- Revision:
- 2:6cd2390302ac
- Parent:
- 1:49fb5754df16
- Child:
- 3:3e5f4d503a66
File content as of revision 2:6cd2390302ac:
// In this example an MQTT client is created. // It is publishing a simple 'example/hello' message with payload 'Hello World.' // and subscribes to 'outdoor/temperature' messages assumably published by other client(s). // Ethernet connection is assured via an ENC28J60 module. #include "mbed.h" #include <UIPEthernet.h> #include <UIPClient.h> #include <MQTTClient.h> #include <string> using namespace std; Serial pc(USBTX, USBRX); // UIPEthernet is the name of a global instance of UIPEthernetClass. // Do not change the name! It is used within the UIPEthernet library. // Adapt the SPI pin names to your mbed platform/board if not present yet. #if defined(TARGET_LPC1768) UIPEthernetClass UIPEthernet(p11, p12, p13, p8); // mosi, miso, sck, cs #elif defined(TARGET_LPC1114) UIPEthernetClass UIPEthernet(dp2, dp1, dp6, dp25); // mosi, miso, sck, cs #elif defined(TARGET_LPC11U68) UIPEthernetClass UIPEthernet(P0_9, P0_8, P1_29, P0_2); // mosi, miso, sck, cs #elif defined(TARGET_NUCLEO_F103RB) UIPEthernetClass UIPEthernet(PB_5, PB_4, PB_3, PB_6); // mosi, miso, sck, cs #endif // Make sure that the MAC number is unique within the connected network. const uint8_t MY_MAC[6] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05 }; // IP address must be unique and compatible with your network too. Change as appropriate. const IPAddress MY_IP(192, 168, 1, 181); char message_buff[100]; IPAddress serverIP(192, 168, 1, 30); // MQTT broker (e.g. 'Mosquitto' running on a Raspberry Pi or Linux machine) EthernetClient ethernetClient; void onMqttMessage(char* topic, uint8_t* payload, unsigned int length); MQTTClient mqttClient(serverIP, 1883, onMqttMessage, ethernetClient); /** * @brief * @note * @param * @retval */ int main(void) { const int MAX_COUNT = 5; int i = 0; bool connected = false; char* payload = "Hello World."; time_t t = 0; time_t lastTime = t; // initialize the ethernet device UIPEthernet.begin(MY_MAC, MY_IP); // The MQTT broker is like a post office distributing messages published by clients to all subscribers (clients). // So the 'example/hello' messages published by this client will be sent via the broker to all clients which subscribed to such messages. // This way also this client will receive all subscribed messages (in this case 'outdoor/temperature' messages) // published by other clients (however not directly but via the broker). pc.printf("Connecting to MQTT broker ..\r\n"); do { wait(1.0); connected = mqttClient.connect("myMQTTHelloClient"); } while(!connected && (i < MAX_COUNT)); if(connected) { pc.printf("MQTT broker connected.\r\n"); mqttClient.subscribe("outdoor/temperature"); pc.printf("Subscribed to: outdoor/temperature\r\n"); } else { pc.printf("Failed to connect to MQTT broker.\r\n"); } while(1) { t = time(NULL); if(t > (lastTime + 5)) { lastTime = t; if(connected) { mqttClient.publish("example/hello", payload); pc.printf("Published: example/hello\r\n"); } } mqttClient.loop(); // MQTT client loop processing } } /** * @brief Called on new MQTT message arrival * @note * @param topic: The topic of the new message * payload: The payload of the new message * length: Payload's length * @retval */ void onMqttMessage(char* topic, uint8_t* payload, unsigned int length) { int i = 0; pc.printf("Message arrived:\r\n"); pc.printf(" Topic: %s\r\n", topic); pc.printf(" Length: %d\r\n", length); // create character buffer with ending null terminator (string) for(i = 0; i < length; i++) { message_buff[i] = payload[i]; } message_buff[i] = '\0'; pc.printf(" Payload: %s\r\n", message_buff); }