WiFi SMS Gateway

Thomas Jespersen — Fri, 04 Sep 2009 23:04:00 +0000

After a long search on the internet, trying to find a cheap SMS Gateway, I got the idea to create one myself.
As I already had a GM862 module laying around, and I’ve got the WiShield WiFi module for the Arduino too, I thought it would be easy – but it wasn’t!

The hardware setup is pretty easy, except the powering for the GM862, as it requires about 3.8V. That was made with a Linear LT1528 3A low dropout voltage regulator.
After alot of testing and measuring, I finally made a working circuit, and afterwards an Eagle Schematic.

WiFi SMS Gateway - Schematic

In the following picture you will see the hardware setup, which consists of the Arduino with the WiShield on the top, the GM862 on two breadboards, and alot of wires!

WiFi SMS Gateway - Hardware

But the real problems appeared when I started programming! I had alot of troubles with the serial connection between the Arduino and the GM862 module, which apparently wasn’t caused by the hardware setup!

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After alot of debugging I figured it out, and a simple SMS sending code was working
Then after a couple of hours I’ve added the WiFi parsing code which sends an SMS to the requested number, with the requested message, read from the GET parameters!

You can grab the code here, and try it out:

/*

 * WiFi SMS Gateway sketch by Thomas Jespersen - http://elec.tkjweb.dk/blog

 * --- Remeber to change the PIN, if any, in the setup() routine! ---

 */
#include 
#define WIRELESS_MODE_INFRA	1

#define WIRELESS_MODE_ADHOC	2
// Wireless configuration parameters ----------------------------------------

unsigned char local_ip[] = {192,168,1,111};	// IP address of WiShield

unsigned char gateway_ip[] = {192,168,2,254};	// router or gateway IP address

unsigned char subnet_mask[] = {255,255,255,0};	// subnet mask for the local network

const prog_char ssid[] PROGMEM = {"SSID"};		// max 32 bytes

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TKJ Electronics » WiShield

WiFi SMS Gateway