The Vodafone K3770 and K3772-Z modems allow you to connect your mbed to the internet from (almost) any location in the world.

The K3770/K3772-Z modems can be purchased directly from :

• Vodafone

Many supermarkets and independent phone stores also sell these modems.

Hardware Setup¶

Because of the high current that the USB dongle requires, it is not possible to power it from the Vu pin on the mbed. In the example show, an external linear regulator board has been used to provide a high current regulated 5v supply from a 9v wall adaptor. The parts shown are :

• USB A Socket
• Breadboard Power Supply
• Breadboard
• Jumper Wires
• 9v wall power supply

Hello World¶

This example application uses the VodafoneUSBModem and the HTTPClient interface, enabling the mbed to fetch a URL over HTTP, and print the contents.

There are various other "hello world" programs that demonstrate SMS, NTP, Socket and Websocket interfaces, as well as management commands (check balance, link status, etc). See "Resources" section below.

You'll notice that this "Hello World" program is a little more complex that others, as we're using the mbed RTOS to manage the memory and processing resources/requirement of the USB Modem driver and the TCP/IP stack.

00001 #include "mbed.h"
00002 #include "VodafoneUSBModem.h"
00003 #include "HTTPClient.h"
00004 
00005 void test(void const*) 
00006 {
00007     VodafoneUSBModem modem;
00008     HTTPClient http;
00009     char str[512];
00010     
00011     int ret = modem.connect("pp.vodafone.co.uk");
00012     if(ret)
00013     {
00014       printf("Could not connect\n");
00015       return;
00016     }
00017     
00018     //GET data
00019     printf("Trying to fetch page...\n");
00020     ret = http.get("http://mbed.org/media/uploads/donatien/hello.txt", str, 128);
00021     if (!ret)
00022     {
00023       printf("Page fetched successfully - read %d characters\n", strlen(str));
00024       printf("Result: %s\n", str);
00025     }
00026     else
00027     {
00028       printf("Error - ret = %d - HTTP return code = %d\n", ret, http.getHTTPResponseCode());
00029     }
00030     
00031     //POST data
00032     HTTPMap map;
00033     HTTPText text(str, 512);
00034     map.put("Hello", "World");
00035     map.put("test", "1234");
00036     printf("Trying to post data...\n");
00037     ret = http.post("http://httpbin.org/post", map, &text);
00038     if (!ret)
00039     {
00040       printf("Executed POST successfully - read %d characters\n", strlen(str));
00041       printf("Result: %s\n", str);
00042     }
00043     else
00044     {
00045       printf("Error - ret = %d - HTTP return code = %d\n", ret, http.getHTTPResponseCode());
00046     }
00047     
00048     modem.disconnect();  
00049 
00050     while(1) {
00051     }
00052 }
00053 
00054 
00055 int main()
00056 {
00057   Thread testTask(test, NULL, osPriorityNormal, 1024 * 4);
00058   DigitalOut led(LED1);
00059   while(1)
00060   {
00061     led=!led;
00062     Thread::wait(1000);  
00063   }
00064 
00065   return 0;
00066 }

Library¶

Resources and references¶

Network APN¶

To connect to the internet you must establish a PPP connection. You can then use BSD Sockets or any high-level component (HTTP Client, NTP Client).

To establish this connection, one single function is used:

int ret = modem.connect("pp.vodafone.co.uk");

pp.vodafone.co.uk is the APN value for a Vodafone Pay as you Go SIM. Change it to the relevant value if your SIM is different:

For details please check Vodafone's dedicated page.

The variable, "ret", allows you to check whether the connection was successful or not (0 on success, a negative value on error).

Please note that the "connect" command can take a few minutes to complete in worst case scenarios, as it initializes the modem and then waits for network registration.

Other Examples¶

Click here to the programs that are using the NTPClient

Click here to the programs that are using the WebsocketClient