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Arduino with GSM sends data to Phone App

nicolaoscon96

Hello, community of element14,

Long time since I last been here and I need your help once more. Am working on a project (a DIY remote control system for cars) using a phone app (not everyone can buy a new car with these cool features) :). This comes in 2 parts, one is the android application I have developed and the second is the "brain" that is in the car which is an Arduino mega with a GSM shield and some relays to control different things in the car, like the windows, start-stop the engine, lights, etc... Until now everything works perfectly for more than 4 months. Once the car's engine turns off the system comes online, and sends an SMS that is online. Instead of writing and sending the commands one by one from the phone's SMS app, I made an app with buttons that when you press it sends a preinstalled SMS directly to the Arduino (for example when I press the start engine it will send an SMS engine_Start) and the Arduino will control the relays to start the engine. The image I attached is the GUI that is still in development. At the top right and left sides are some text views for current fuel and temperature. So until now, this was kinda one-way communication from the phone's app to the Arduino although I get a report back when each command is being executed. I want to add something else as well.

And this is where I need your help. I want to send the data from Arduino to the phone via SMS like is working now in a String and the app will break it and at the data to the corresponding place. For example, take the temperature from a sensor         (int inTemp) and the fuel level (int fuelLevel) and add them in a String like (String data ="&" + inTemp + "&" + fuelLevel) and when the SMS comes back to the phone the app will break that SMS the String and separate the data by knowing that anything after the symbol & is considered data and add them in the textview.

Did anyone work with anything like this? 

Note the application is written in Java and I use an Android phone.

 image

Regards,

Nikolas

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  • +1

    Hi,

    I have not done it, but you might want to pick some standard format, and then there may be existing Java code to do the parsing that you desire. Otherwise you'll have to write the code yourself, but I don't see the issue, it is usually straightforward to split a string into tokens and search for text and pull out fragments of the string. These are all typical features of string libraries in any language (but you should write higher-level functions to deal with your data, if you intend to create a custom format for which there may be no existing code online).

    Personally, I like JSON, but you may find it is too verbose for SMS. There are standards you could check like https://smpp.org/ I think they mention a TLV format (i.e. tag/length/value) for instance. There are many possible candidate formats, so it's really up to you, whatever you feel comfortable with, and if you can find existing code, or if you are planning on writing your own using (say) string libraries.

Reply
  • +1

    Hi,

    I have not done it, but you might want to pick some standard format, and then there may be existing Java code to do the parsing that you desire. Otherwise you'll have to write the code yourself, but I don't see the issue, it is usually straightforward to split a string into tokens and search for text and pull out fragments of the string. These are all typical features of string libraries in any language (but you should write higher-level functions to deal with your data, if you intend to create a custom format for which there may be no existing code online).

    Personally, I like JSON, but you may find it is too verbose for SMS. There are standards you could check like https://smpp.org/ I think they mention a TLV format (i.e. tag/length/value) for instance. There are many possible candidate formats, so it's really up to you, whatever you feel comfortable with, and if you can find existing code, or if you are planning on writing your own using (say) string libraries.

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