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.

main.cpp@1:a1d5c7a6acbc, 2014-02-05 (annotated)

Committer:
icraggs
Date:
Wed Feb 05 10:50:15 2014 +0000
Revision:
1:a1d5c7a6acbc
Parent:
0:0cae29831d01
Child:
2:638c854c0695
Add copyright statement to main program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icraggs 1:a1d5c7a6acbc 1 /*******************************************************************************
icraggs 1:a1d5c7a6acbc 2 * Copyright (c) 2014 IBM Corp.
icraggs 1:a1d5c7a6acbc 3 *
icraggs 1:a1d5c7a6acbc 4 * All rights reserved. This program and the accompanying materials
icraggs 1:a1d5c7a6acbc 5 * are made available under the terms of the Eclipse Public License v1.0
icraggs 1:a1d5c7a6acbc 6 * and Eclipse Distribution License v1.0 which accompany this distribution.
icraggs 1:a1d5c7a6acbc 7 *
icraggs 1:a1d5c7a6acbc 8 * The Eclipse Public License is available at
icraggs 1:a1d5c7a6acbc 9 * http://www.eclipse.org/legal/epl-v10.html
icraggs 1:a1d5c7a6acbc 10 * and the Eclipse Distribution License is available at
icraggs 1:a1d5c7a6acbc 11 * http://www.eclipse.org/org/documents/edl-v10.php.
icraggs 1:a1d5c7a6acbc 12 *
icraggs 1:a1d5c7a6acbc 13 * Contributors:
icraggs 1:a1d5c7a6acbc 14 * Ian Craggs - initial API and implementation and/or initial documentation
icraggs 1:a1d5c7a6acbc 15 *******************************************************************************/
icraggs 1:a1d5c7a6acbc 16
icraggs 0:0cae29831d01 17 #include "mbed.h"
icraggs 0:0cae29831d01 18 #include "EthernetInterface.h"
icraggs 0:0cae29831d01 19 #include "C12832_lcd.h"
icraggs 0:0cae29831d01 20
icraggs 0:0cae29831d01 21 #include "MQTTPacket.h"
icraggs 0:0cae29831d01 22
icraggs 0:0cae29831d01 23 DigitalOut myled(LED2);
icraggs 0:0cae29831d01 24 C12832_LCD lcd;
icraggs 0:0cae29831d01 25
icraggs 0:0cae29831d01 26 int publish()
icraggs 0:0cae29831d01 27 {
icraggs 0:0cae29831d01 28 MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
icraggs 0:0cae29831d01 29 int rc = 0;
icraggs 0:0cae29831d01 30 char buf[200];
icraggs 0:0cae29831d01 31 int buflen = sizeof(buf);
icraggs 0:0cae29831d01 32 TCPSocketConnection mysock;
icraggs 0:0cae29831d01 33 MQTTString topicString = MQTTString_initializer;
icraggs 0:0cae29831d01 34 char* payload = "I'm alive!";
icraggs 0:0cae29831d01 35 int payloadlen = strlen(payload);
icraggs 0:0cae29831d01 36 int len = 0;
icraggs 0:0cae29831d01 37
icraggs 0:0cae29831d01 38 mysock.connect("m2m.eclipse.org", 1883);
icraggs 0:0cae29831d01 39
icraggs 0:0cae29831d01 40 data.clientID.cstring = "mbed test client - Ian Craggs";
icraggs 0:0cae29831d01 41 data.keepAliveInterval = 20;
icraggs 0:0cae29831d01 42 data.cleansession = 1;
icraggs 0:0cae29831d01 43 data.MQTTVersion = 3;
icraggs 0:0cae29831d01 44
icraggs 0:0cae29831d01 45 len = MQTTSerialize_connect(buf, buflen, &data);
icraggs 0:0cae29831d01 46
icraggs 0:0cae29831d01 47 topicString.cstring = "mbed NXP LPC1768";
icraggs 0:0cae29831d01 48 len += MQTTSerialize_publish(buf + len, buflen - len, 0, 0, 0, 0, topicString, payload, payloadlen);
icraggs 0:0cae29831d01 49
icraggs 0:0cae29831d01 50 len += MQTTSerialize_disconnect(buf + len, buflen - len);
icraggs 0:0cae29831d01 51
icraggs 0:0cae29831d01 52 rc = 0;
icraggs 0:0cae29831d01 53 while (rc < len)
icraggs 0:0cae29831d01 54 {
icraggs 0:0cae29831d01 55 int rc1 = mysock.send(buf, len);
icraggs 0:0cae29831d01 56 if (rc1 == -1)
icraggs 0:0cae29831d01 57 {
icraggs 0:0cae29831d01 58 lcd.printf("Send failed\n");
icraggs 0:0cae29831d01 59 break;
icraggs 0:0cae29831d01 60 }
icraggs 0:0cae29831d01 61 else
icraggs 0:0cae29831d01 62 rc += rc1;
icraggs 0:0cae29831d01 63 }
icraggs 0:0cae29831d01 64 if (rc == len)
icraggs 0:0cae29831d01 65 lcd.printf("Send succeeded\n");
icraggs 0:0cae29831d01 66 wait(0.2);
icraggs 0:0cae29831d01 67
icraggs 0:0cae29831d01 68 return 0;
icraggs 0:0cae29831d01 69 }
icraggs 0:0cae29831d01 70
icraggs 1:a1d5c7a6acbc 71 int main()
icraggs 1:a1d5c7a6acbc 72 {
icraggs 0:0cae29831d01 73 EthernetInterface eth;
icraggs 0:0cae29831d01 74 eth.init(); //Use DHCP
icraggs 0:0cae29831d01 75 eth.connect();
icraggs 0:0cae29831d01 76 lcd.printf("IP Address is %s\n", eth.getIPAddress());
icraggs 0:0cae29831d01 77
icraggs 1:a1d5c7a6acbc 78 while(1)
icraggs 1:a1d5c7a6acbc 79 {
icraggs 0:0cae29831d01 80 myled = 1;
icraggs 0:0cae29831d01 81 publish();
icraggs 0:0cae29831d01 82 wait(0.2);
icraggs 0:0cae29831d01 83 myled = 0;
icraggs 0:0cae29831d01 84 publish();
icraggs 0:0cae29831d01 85 wait(0.2);
icraggs 0:0cae29831d01 86 }
icraggs 0:0cae29831d01 87
icraggs 0:0cae29831d01 88 eth.disconnect();
icraggs 0:0cae29831d01 89 }