Introduction: SIM900 GSM Based Weather Notifier

About: An electronics hobbyist

We always need weather updates on our mobile phone. It can either be from online app or system app using internet. But here I'll show you a way to use the Text Messaging feature on our mobiles to get the Temperature and Humidity updates, you can extend it too to get pressure and altitude and GPS updates. Here I used a DHT22 to get temperature and humidity updates but you can also use a BMP280 to get pressure updates too. Obviously I used an Arduino for the entire calculations and SIM900 for the SMS sending process. Since using Arduino will be easy for most users, but actually you can use any microcontroller for the entire process. For that you will need to read the datasheet of SIM900 and DHT22. So for now I will use simply Arduino UNO for this. Nano,Mega,Micro will work too...

Step 1: Parts Required

1. Arduino UNO/Nano/Mega/Micro

2. SIM900/800

3. 1 10K resistor

4. DHT22/DHT11

5. Jumpers

6. Breadboard( may not be necessary)

7. Separate Power supply for SIM900/800

Step 2: Working Method and Making the Circuit Connections

The SIM900/800 is a GSM module that works on TX-RX methods and uses AT commands.A normal 3g sim card can be placed here and you can also make and receive calls if you attach a microphone here, but I'm not using that feature here. Here I will use the messaging facility of SIM900. SIM900 can make calls,receive calls, make and send text messages. You can recharge your sim with a messaging pack and then use it to prevent overcharging due to multiple SMS.

Here the DHT22 will get temperature and Humidity data and this will be send to the user as a text message. So suppose the DHT22 and the SIM900 is in your home and you are in your office. So you can make the system to send text messages to the user after every 3hrs . You can customize that time too in the code attached below.

The circuit connections are too easy and simple. Use jumpers for every connection.

The SIM900 module have different versions. My version uses a 12V 1A adapter to power it. Another model can require 5V supply. So look at your version carefully before using it, and also remember that they are static sensitive device. So don't keep it near thermocol or plastics.

Step 3: Uploading Code

Now after connections power up the GSM module first with the SIM card loaded. Now watch if the LED on the module is blinking. If it is blinking too fast(1 blink/sec) then pull out the TX and RX connections and reinsert it.At normal it should blink at 1 blink/3 sec. If it at 1blink/3sec then you can confirm the SIM is now ready to use.

Then open up arduino IDE and open the sketch attached here. Give your phone number in the sketch in which the SIM900 should send message. Then upload it. You should see message sending after the specified time interval. You can change it too in the code.

You are now all set and get updated with the current weather.

You can add BMP280 to get pressure updates or anything you may like. You can see the status of your water tank, attach PIR sensor to detect the presence of human in your house,etc..

for any problem comment down here or mail at

Arduino Contest 2017

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Arduino Contest 2017