In this post you will find the Arduino MQTT libraries which i used in my tutorial where i showed how to form MQTT packets and also how to send MQTT Publish and Subscribe packets to free MQTT brokers like CloudMQTT, Adafruit.io and Mosquitto.org. Go ahead and download the code and have fun experimenting. 

Hello guys, In this post we will see a list of 3G modules that work with Australian 3G network providers. Unlike other countries, the Australian networks use a slightly different frequency bands, especially Telstra, the leading network provider in Australia. Almost all other carriers, like Optus,,Virgin Mobiles and Vodafone follow standard European frequency bands.

In this post you will see how we built a 3G GPS tracking device or Foaling alarm which can be used for vehicle as well as personal tracking. This is nothing but my same VALTRACK series design with almost the same parts and a few additional features. Due to the 3G module used, the design became a slightly bigger. 

This post is coming out of frustration caused by ZOHO mail. The free mail hosting provider, who also provides paid email hosting plans has limited the free email hosting service access to webmail only, which means, we cant access the mail from outside clients like Microsoft outlook. Earlier i used Zoho mail for accessing one of my domains email since i only had a few users and Zoho mail was the best possible solution at that time.

In this post we will learn the differences between the old GSM+GNSS enabled combo modules SIM808 and the new module SIM868. The SIM868 is a newer module with a very small form factor which keeps all the benefits of SIM808 and extends the features in some areas.  Both the modules are quad band modules and this post should enable you to make the right selection. 

In this post we will learn the differences between the 3G modules in SIM5320 and SIM5360 series. Both these modules from SIMCOM 3G/UMTS/WCDMA module family are almost compatible except these major differences. I almost selected SIM5360E module for one of my design but had to change at the very last moment to SIM5320E. Lets find out why. 

I had been experimenting with MQTT and was able to publish and subscribe messages through different local and cloud MQTT brokers successfully. But when it came to the next step of saving and viewing these published messages, i couldn't find any easy and simpler way of doing this. The best i could find was that we can subscribe to a wildcard topic and receive all message coming to the broker as a subscriber and save it to a database using some client libraries. 

In this post we will see and understand how we can use the DTMF feature of SIM900 /SIM800  GSM modules for controlling devices or appliances. First i will show you how to enable the DTMF detection feature using an AT command and then we can see how we can write some simple Arduino code to detect the different DTMF tones and control a LED based on it.

Are you wondering how to auto turn on the GSM modules like SIM900 or SIM800. This article is just for you. Although these modules come with a PWRKEY button, we sometimes need the device to turn on or boot up automatically once the power is supplied. 

In this post i will show you a new version of the GPS tracker i designed for a client in Europe. I got this requirement when i was designing my VALTRACK-V2 GPS tracker. The product is a modified version of my VALTRACK-V2 design.