385.Making calls and sending messages with Arduino and GSM modules Microcontrollers sometimes have difficulty communicating with the GSM Module, specifically for functions such as SMS, calls, and texting. With the help of the Arduino, we will build a simple mobile phone. The GSM Module involved in this project can make and receive calls, as well as send and receive SMS, and the Arduino phone also has a Microphone and Speaker so you can talk over it. Besides interfacing with the GSM Module, the project will be able to run any phone's basic functions by using all the necessary code on the Arduino.

Arduino Uno GSM Module SIM900 16x2 LCD, 4x4 Keypad Breadboard or PCB Connecting jumper wire Power supply Speaker, MIC SIM Card

Arduino Uno is used to control all the features of this Arduino Mobile Phone Project, as well as to interface all the components. An alphanumeric keypad is used to make all kinds of inputs, such as entering mobile numbers, typing messages, making and receiving calls, and sending and receiving SMS. The GSM Module communicates with the network in order to make and receive calls and messages. As well as ICs and speakers, a 16x2 LCD shows messages, instructions, alerts, and a MIC picks up the voice call and ring sound. Using the same keypad for both numbers and alphabets, alphanumeric is a way to enter data. Check out the Code in Code section below for the Arduino code to accept the 4x4 keypad interface as well.

It is easy to work on this project. We will use an alphanumeric keypad to handle all the features. For a full understanding of the process, please check out the code and demo video below. In this section, we will describe all four features of the following projects.

If you want to call someone from your Arduino Phone, you have to press the 'C' button, and then enter their Mobile Number. An alphanumeric keypad is used for entering the number. Again, we need to press 'C' once the number has been entered. As soon as Arduino receives the AT command, it will

ATDxxxxxxxxxx; <Enter> where xxxxxxxxx is entered Mobile Number.

Getting a call is a very straightforward process. In the event that a call is made to your GSM module SIM number, then your system will display an "Incoming... The LCD will display the incoming number of the caller. The only thing we need to do now is press 'A' to attend this call. When we press

'A', Arduino will be programmed to send the following command to GSM

ATA <enter>

Our Arduino based mobile phone allows us to send a SMS by pressing the B key. In order to send an SMS, we must enter the Recipient Number, which is 'to whom' we should send the SMS. The LCD now asks for a message once we have entered the number and pressed 'D'. Once we've typed our message, we need to hit 'D' to send it, like we do on a traditional mobile phone. When we've done that, we should be able to send an SMS. An Arduino sends a

AT+CMGF=1 <enter> AT+CMGS=”xxxxxxxxxx” <enter> where: xxxxxxxxxx is entered mobile number And send 26 to GSM to send SMS.

In addition, this feature is easy to use. SIM cards are used to receive SMS, which are then stored in GSM cards. With Arduino, the UART transmitting SMS information is continuously monitored. If you see the SMS symbol (look at the video at the end) on the LCD, you need to press 'D' to read the SMS. As shown in the example below, the SMS Received indicator shows

+CMTI: “SM” <SMS stored location> +CMTI: “SM”,6. 6 refers to the SIM card location where the message is stored.

Arduino extracts the SMS storing location and sends a command to GSM to read the SMS when it receives this indication that an SMS has been received. Afterward, the LCD will show a 'New Message Symbol'. AT+CMGR=<SMS stored location><enter> AT+CMGR=6 Next, Arduino receives the stored message from GSM and before reading this message it shows it on the LCD, and then after reading the messages it clears the 'New SMS symbol' on the LCD. Note: There is no coding for the microphone and speaker.

Diagram showing how GSM SIM900 and Arduino can be interconnected is shown above. Pin 14 is connected to pins 15, 16, 17, 18, 19 of Arduino, while pins EN, D4, D5 and D6 are connected to pin 16 of the LCD. (Ground of Arduino and GSM are connected.) The RX and TX pins of the GSM module are directly connected to Arduino's pins D3 and D2. Row pins R1, R2, R3, R4 of the 4x4 keypad are directly connected to pins 11, 10, 9, 8 of Arduino, and column pins C1, C2, C3 are directly connected to pins 7, 6, 5,

4 of Arduino. The MIC pins of the GSM Module are directly connected to mic+ and mic-, and the speaker pins are directly connected to pin SP+ and SP- for the GSM Module.