Send SMS Using SIM900 GSM Shield & Arduino - Visuino Tutorial

2026-04-06 | By Ron Cutts

License: GNU Lesser General Public License Microcontrollers Wifi Arduino ESP32

In this tutorial, you will learn how to send sms using the SIM900 GSM Shield and Visuino.

With one button, we will set the GSM shield into text message mode, set the number and the text message, and with the second button, we are going to send sms.

You will also learn how to use the "Serial Software" component in Visuino.

Watch the Video!

Also check out this tutorial: Make a Phone Call Using the SIM900 GSM Shield & Arduino - Visuino Tutorial

Learn more about Visuino: What is Visuino

What You Will Need

SIM900 GSM Shield
Arduino UNO
SIM card (You should disable the PIN request on the SIM card before using it with the GSM shield)
Breadboard
2X button
2X 1Kohm resistor
Jumper wires
5V power supply with enough amps for the shield
Visuino program: Download Visuino

What You Will Need

What You Will Need photo 2

What You Will Need photo 3

What You Will Need photo 4

What You Will Need photo 5

What You Will Need photo 6

What You Will Need photo 7

What You Will Need photo 8

What You Will Need photo 9

The Circuit

Connect the SIM900 GSM Shield to the Arduino

Connect Arduino pin [5V] to breadboard positive pin [Red line]
Connect Arduino pin [GND] to breadboard negative pin [Black line]

Connect Arduino Digital pin [2] to button1 on the breadboard and to Resistor1
Connect the other side of the resistor 1 to the breadboard pin [GND]
Connect the other pin of button 1 to the breadboard positive pin [5V]

Connect Arduino Digital pin [2] to button1 on the breadboard and to Resistor1
Connect the other side of the resistor 1 to the breadboard pin [GND]
Connect the other pin of button 1 to the breadboard positive pin [5V]

Connect with the Jumpers on the shield pins D8(RX) & D7(TX) as you see it in the picture
Make sure that the antenna is connected to the shield
Connect the 5V Power Supply to the shield, and set the switch on the shield to the External Power (See the picture)
Once the Power is connected, hold the Power button for 2 seconds
Once the connection with the Network is established, the LED will blink every 3 seconds

The Circuit

The Circuit photo 2

The Circuit photo 3

Start Visuino, and Select the Arduino UNO Board Type

Start Visuino as shown in the first picture. Click on the "Tools" button on the Arduino component (Picture 1) in Visuino. When the dialog appears, select "Arduino UNO" as shown in Picture 2

Start Visuino, and Select the Arduino UNO Board Type

Start Visuino, and Select the Arduino UNO Board Type photo 2

In Visuino, Add Components

Add "Software Serial Port" component
Add "Add "Text Value" component
Add 2X "Debounce Button" component
Add 3X "Delay" component
Add "Char Value" component
Add "Text Multi-Source Merger" component

In Visuino Add Components

In Visuino Add Components photo 2

In Visuino Add Components photo 3

In Visuino Add Components photo 4

In Visuino Add Components photo 5

In Visuino Add Components photo 6

In Visuino Set Components

Double-click on the "TextValue1" and in the Elements window
Command to set GSM shield to text mode: drag "Set Value" to the left side and in the properties window set "Value" to AT+CMGF=1
Command to set Phone number (International Format): drag another "Set Value" to the left side and in the properties window set "Value" to AT+CMGS="+495XXXXXX"
Command to set Text Message: In the Elements window, drag another "Set Value" to the left side, and in the properties window, set "Value" to Hello from Visuino
Close the Elements window
Select "Delay2" and in the properties window set "Interval (uS)" to 2000000
Select "CharValue1" and in the properties window set "Value" to #26

In Visuino Set Components

In Visuino Set Components photo 2

In Visuino Set Components photo 3

In Visuino Set Components photo 4

In Visuino Set Components photo 5

In Visuino Set Components photo 6

In Visuino Connect Components

Connect Arduino digital pin [2] to "Button1" pin [In]
Connect Arduino digital pin [3] to "Button2" pin [In]
Connect "Button1" pin [Out] to "TextValue1" > "Set Value1" pin [In]
Connect "Button1" pin [Out] to "Delay1" pin [Start]
Connect "Button1" pin [Out] to "Delay2" pin [Start]
Connect "Delay1" pin [Out] to "TextValue1" > "Set Value2" pin [In]
Connect "Delay2" pin [Out] to "TextValue1" > "Set Value3" pin [In]
Connect "Button2" pin [Out] to "Delay3" pin [Start]
Connect "Delay3" pin [Out] to "CharValue1" pin [Clock]
Connect "TextValue1" pin [Out] to "TextMultiMerger1" pin [0]
Connect "CharValue1" pin [Out] to "TextMultiMerger1" pin [1]
Connect "TextMultiMerger1" pin [Out] to "SoftwareSerial1" pin [In]
Connect "SoftwareSerial1" pin [RX] to Arduino Digital pin [7]
Connect "SoftwareSerial1" pin [TX] to Arduino Digital pin [8]

Optional if you want to monitor response from the GSM shield: Connect "SoftwareSerial1" pin [Out] to Arduino Serial pin [In]

In Visuino Connect Components

In Visuino Connect Components photo 2

Generate, Compile, and Upload the Arduino Code

In Visuino, at the bottom, click on the "Build" Tab, make sure the correct port is selected, then click on the "Compile/Build and Upload" button.

Generate, Compile, and Upload the Arduino Code

Play

When you power the Shield, wait a bit for the connection with the network to be established. Once the connection is established, the LED on the shield will blink every 3s.

Now you can press a button and the GSM shield will go into Text Messages Mode, and it will set the phone number and set the Text message. To send SMS, just press the other button.

Congratulations! You have completed your GSM project with Visuino. Also attached is the Visuino project that I created for this. You can download and open it in Visuino: https://www.visuino.eu