jim hamblen / Mbed OS 4180_TCPSocket_Example

Alternative TCPSocket example using an HTTP GET to read a short "helloworld" text web page using a different server

Fork of ARMs demo HTTP socket demo. ARM's server was redirected and the demo was no longer working. An alternative server was setup and the code was modified to display the web page text in addition to just "200 OK". Only works for a very short web page - buffer only 400 characters but RAM is running out on the LPC1768 in the demo! Data read from the web page is read and parsed to control the mbed's 4 LEDs for a basic IoT demo.

Files at this revision

API Documentation at this revision

Revision 6:9cf6630fa25d, committed 2021-02-17

Comitter:
4180_1
Date:
Wed Feb 17 18:55:05 2021 +0000
Parent:
5:66c4a71d22e9
Commit message:
ver 1.2 Added Basic IoT demo controlling LEDs from web page data

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/main.cpp	Mon Feb 15 18:19:25 2021 +0000
+++ b/main.cpp	Wed Feb 17 18:55:05 2021 +0000
@@ -1,15 +1,16 @@
 #include "mbed.h"
 #include "EthernetInterface.h"
-
+BusOut leds(LED1,LED2,LED3,LED4); //LEDs are controlled by web page text data
 // Network interface
 EthernetInterface net;
 
 // Socket demo
-int main() {
+int main()
+{
     // Show MAC in case it is needed to enable DHCP on a secure network
     char mac[6];
     mbed_mac_address(mac);
-    printf("\r\rmbed's MAC address is %02x:%02x:%02x:%02x:%02x:%02x\n\r", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]); 
+    printf("\r\rmbed's MAC address is %02x:%02x:%02x:%02x:%02x:%02x\n\r", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
     // Bring up the ethernet interface
     printf("Waiting for IP address from DHCP Server\n\r");
     wait(1.0);
@@ -35,11 +36,21 @@
     char rbuffer[400]; //enough for a very short text page - almost out of RAM!
     int rcount = socket.recv(rbuffer, sizeof rbuffer);
     rbuffer[rcount] = 0; //terminate to print as a C string;
+    //Print packet read from HTTP web page server
     printf("recv %d [%.*s]\n\r", rcount, strstr(rbuffer, "\r\n"), rbuffer);
 
     // Close the socket to return its memory and bring down the network interface
     socket.close();
 
+    // Basic IoT demo controlling mbeds 4 LEDs from Internet web page's ASCII text data
+    // Web page demo contains a line "Data:0101"
+    char *data;
+    data = strstr(rbuffer,"Data:"); //Find Data: line on web page with '0's or '1's
+    data = data + 5; //Skip to data
+    for (int i=0; i<=3; i++) //Parse 4 web page characters to control LEDs
+        leds[i] = data[i] - '0'; //convert ASCII '0' or '1's to binary to control 4 leds
+    //Another device could change the web page contents to control LEDs from anywhere
+
     // Bring down the ethernet interface
     net.disconnect();
     printf("Done\n\r");