NB! This has been included in the MySensors Development branch via PR: https://github.com/mysensors/MySensors/pull/1097 Only follow the below instructions if you are using MySensors version < 2.3

Ever wanted to set up a MySensors network in a remote location only to realize you do not have WiFi coverage? Well, worry not, there is a solution. Using a cheap GSM modem module and a pre-paid phone card, you can have your network up and running anywhere with cell coverage.

Build instructions: Download the included MyGatewayTransportMQTTClient.cpp file and copy it in your Arduino/library/MySensors folder. NB! Back up your old file.

Connect your modem to Arduino via their TX/RX lines. Supply power and ground (Ground needs to be shared)

Edit the sketch (you can find it also under included files) to reflect your hardware and software preferences.

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * REVISION HISTORY
 * Version 1.0 - Rait Lotamõis
 *
 * DESCRIPTION
 * The TinyGSM MQTT gateway sends radio network (or locally attached sensors) data to your MQTT broker using a GSM modem or optionally an ESP8266 as a WiFi modem.
 * The node also listens to MY_MQTT_TOPIC_PREFIX and sends out those messages to the radio network
 *
 * LED purposes:
 * - To use the feature, uncomment WITH_LEDS_BLINKING in MyConfig.h
 * - RX (green) - blink fast on radio message recieved. In inclusion mode will blink fast only on presentation recieved
 * - TX (yellow) - blink fast on radio message transmitted. In inclusion mode will blink slowly
 * - ERR (red) - fast blink on error during transmission error or recieve crc error
 */


// Enable debug prints to serial monitor
#define MY_DEBUG

// Enables and select radio type (if attached)
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95

#define MY_GATEWAY_MQTT_CLIENT

// Enable GSM modem support
#define MY_GATEWAY_TINYGSM

// Define your modem
#define TINY_GSM_MODEM_SIM800
// #define TINY_GSM_MODEM_SIM808
// #define TINY_GSM_MODEM_SIM900
// #define TINY_GSM_MODEM_A6
// #define TINY_GSM_MODEM_A7
// #define TINY_GSM_MODEM_M590
// #define TINY_GSM_ESP8266

// leave empty anything that does not apply
#define MY_GSM_APN  "internet"
//#define MY_GSM_PIN    "1234"
//#define MY_GSM_USR    ""
//#define MY_GSM_PSW  "" //If using a GSM modem, this stands for your GSM connection password. If using WiFi, it's your wireless password.
//#define MY_GSM_SSID ""

// Use Hardware Serial on Mega, Leonardo, Micro
#define SerialAT Serial1
// or Software Serial on Uno, Nano
//#define MY_GSM_RX 4
//#define MY_GSM_TX 5

// If your Mosquitto is old fashioned and does not support 3.1.1
//#define MQTT_VERSION MQTT_VERSION_3_1

// Set this node's subscribe and publish topic prefix
#define MY_MQTT_PUBLISH_TOPIC_PREFIX "mygateway1-out"
#define MY_MQTT_SUBSCRIBE_TOPIC_PREFIX "mygateway1-in"

// Set MQTT client id
#define MY_MQTT_CLIENT_ID "mysensors-1"

// Enable these if your MQTT broker requires usenrame/password
//#define MY_MQTT_USER "username"
//#define MY_MQTT_PASSWORD "password"

// Enable MY_IP_ADDRESS here if you want a static ip address (no DHCP)
//#define MY_IP_ADDRESS 192,168,32,220

// If using static ip you can define Gateway and Subnet address as well
//#define MY_IP_GATEWAY_ADDRESS 192,168,32,1
//#define MY_IP_SUBNET_ADDRESS 255,255,255,0

// MQTT broker ip address or url. Define one or the other.
//#define MY_CONTROLLER_URL_ADDRESS "mymqttbroker.com"
//#define MY_CONTROLLER_IP_ADDRESS 192, 168, 178, 68

// The MQTT broker port to to open
#define MY_PORT 1883

/*
// Enable inclusion mode
#define MY_INCLUSION_MODE_FEATURE
// Enable Inclusion mode button on gateway
//#define MY_INCLUSION_BUTTON_FEATURE
// Set inclusion mode duration (in seconds)
#define MY_INCLUSION_MODE_DURATION 60
// Digital pin used for inclusion mode button
//#define MY_INCLUSION_MODE_BUTTON_PIN  3

// Set blinking period
#define MY_DEFAULT_LED_BLINK_PERIOD 300

// Flash leds on rx/tx/err
// Uncomment to override default HW configurations
//#define MY_DEFAULT_ERR_LED_PIN 16  // Error led pin
//#define MY_DEFAULT_RX_LED_PIN  16  // Receive led pin
//#define MY_DEFAULT_TX_LED_PIN  16  // the PCB, on board LED
*/

#include <Ethernet.h>
#include <MySensors.h>

void setup()
{
    // Setup locally attached sensors
}

void presentation()
{
    // Present locally attached sensors here
}

void loop()
{
    // Send locally attached sensors data here
}