MQTT / Mbed OS HelloMQTT

Sample MQTT program - simple send and receive

Dependencies:   C12832 MQTT

Dependents:   MQTT_G_SENSOR

This program and the MQTT libraries it uses are part of the EclipseTM Paho project; specifically the embedded client.

This example and API are working, but are still in progress. Please give us your feedback.

HelloMQTT is an example of using the MQTT API. The MQTT API is portable across network interface stacks. MQTT is designed to be used with TCP/IP, but any transport with similar characteristics should be suitable.

HelloMQTT uses the NetworkInterface APIs in mbed OS 5 to show how this works. The MQTT library contains an MQTTNetwork.h header, which is a wrapper around the mbed networking interface. To switch between connectivity methods (the default is Ethernet) the easy-connect library is provided in this example application. You can change the connectivity method in mbed_app.json.

Adding new connectivity methods to the program is trivial, as long as they implement the mbed OS 5 NetworkStack API.

Diff: main.cpp

Revision:
5:4a257f6ac09a
Parent:
3:7a6a899de7cc
Child:
7:3de634f2d40c
--- a/main.cpp	Fri May 09 21:33:48 2014 +0000
+++ b/main.cpp	Fri May 09 23:06:43 2014 +0000
@@ -25,121 +25,45 @@
  */
 
 #include "mbed.h"
-#include "EthernetInterface.h"
+#include "EthernetInterfaceIPStack.h"
 
-#include "C12832_lcd.h"
-C12832_LCD lcd;
+#include "C12832.h"
+C12832 lcd(p5, p7, p6, p8, p11);
 
 #include "FP.cpp"
 #include "MQTTClient.h"
 
-
-
-class IPStack 
-{
-public:    
-    IPStack()
-    {
-        eth.init();                          // Use DHCP
-        eth.connect();
-        mysock.set_blocking(false, 1000);    // 1 second Timeout 
-    }
-    
-    int connect(char* hostname, int port)
-    {
-        return mysock.connect(hostname, port);
-    }
-
-    int read(char* buffer, int len, int timeout)
-    {
-        mysock.set_blocking(false, timeout);  
-        return mysock.receive(buffer, len);
-    }
-    
-    int write(char* buffer, int len, int timeout)
-    {
-        mysock.set_blocking(false, timeout);  
-        return mysock.send(buffer, len);
-    }
-    
-    int disconnect()
-    {
-        return mysock.close();
-    }
-    
-private:
-
-    EthernetInterface eth;
-    TCPSocketConnection mysock; 
-    
-};
-
-
-class Countdown
-{
-public:
-    Countdown()
-    {
-        t = Timer();   
-    }
-    
-    Countdown(int ms)
-    {
-        t = Timer();
-        countdown_ms(ms);   
-    }
-    
-    
-    bool expired()
-    {
-        return t.read_ms() >= interval_end_ms;
-    }
-    
-    void countdown_ms(int ms)  
-    {
-        t.stop();
-        interval_end_ms = ms;
-        t.reset();
-        t.start();
-    }
-    
-    void countdown(int seconds)
-    {
-        countdown_ms(seconds * 1000);
-    }
-    
-    int left_ms()
-    {
-        return interval_end_ms - t.read_ms();
-    }
-    
-private:
-    Timer t;
-    int interval_end_ms; 
-};
-
 int arrivedcount = 0;
 
 void messageArrived(MQTT::Message* message)
 {
-    lcd.printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\n", message->qos, message->retained, message->dup, message->id);
-    lcd.printf("Payload %.*s\n", message->payloadlen, (char*)message->payload);
+    lcd.cls();
+    lcd.locate(0,3);
+    printf("Message arrived: qos %d, retained %d, dup %d, packetid %d\n", message->qos, message->retained, message->dup, message->id);
+    printf("Payload %.*s\n", message->payloadlen, (char*)message->payload);
     ++arrivedcount;
+    lcd.puts((char*)message->payload);
 }
 
 int connect(MQTT::Client<IPStack, Countdown>::connectionLostInfo* info)
 {
     char* hostname = "m2m.eclipse.org";
     int port = 1883;
-    lcd.printf("Connecting to %s:%d\n", hostname, port);
+    
+    lcd.cls();
+    lcd.locate(0,3);
+    lcd.printf("%s:%d\n", hostname, port);
+    printf("Connecting to %s:%d\n", hostname, port);
     int rc = info->network->connect(hostname, port);
-    lcd.printf("rc from TCP connect is %d\n", rc);
+    lcd.printf("TCP connect = %d\n", rc);
+    printf("rc from TCP connect is %d\n", rc);
  
     MQTTPacket_connectData data = MQTTPacket_connectData_initializer;       
     data.MQTTVersion = 3;
     data.clientID.cstring = "mbed-icraggs";
     rc = info->client->connect(&data);
-    lcd.printf("rc from MQTT connect is %d\n", rc);
+    lcd.printf("MQTT connect = %d\n", rc);
+    printf("rc from MQTT connect is %d\n", rc);
     
     return rc;
 }
@@ -152,6 +76,7 @@
     char* topic = "mbed-sample";
     
     lcd.printf("Version is %f\n", version);
+    printf("Version is %f\n", version);
               
     MQTT::Client<IPStack, Countdown> client = MQTT::Client<IPStack, Countdown>(ipstack);
     
@@ -161,8 +86,9 @@
     int rc = connect(&info);
     
     rc = client.subscribe(topic, MQTT::QOS1, messageArrived);   
-    if (rc != 0)
-        lcd.printf("rc from MQTT subscribe is %d\n", rc);
+    if (rc != 0) {
+        printf("rc from MQTT subscribe is %d\n", rc);
+    }
 
     MQTT::Message message;
 
@@ -195,16 +121,21 @@
         client.yield(100);
     
     rc = client.unsubscribe(topic);
-    if (rc != 0)
-        lcd.printf("rc from unsubscribe was %d\n", rc);
+    if (rc != 0) {
+        printf("rc from unsubscribe was %d\n", rc);
+    }
     
     rc = client.disconnect();
-    if (rc != 0)
-        lcd.printf("rc from disconnect was %d\n", rc);
+    if (rc != 0) {
+        printf("rc from disconnect was %d\n", rc);
+    }
     
     ipstack.disconnect();
     
-    lcd.printf("Finishing with %d messages received\n", arrivedcount);
+    lcd.cls();
+    lcd.locate(0,3);
+    lcd.printf("Finish: %d msgs\n", arrivedcount);
+    printf("Finishing with %d messages received\n", arrivedcount);
     
     return 0;
 }