Send a message from Arduino to smartphone using matrix keyboard

Arduino is an open-source electronics platform based on simple software and hardware. It can be used to control a wide variety of devices, including LEDs, motors, and sensors. Bluetooth is a wireless communication technology that allows devices to connect to each other over short distances. Arduino boards can be used with Bluetooth modules to enable wireless communication between devices. This can be used for a variety of applications, such as controlling a robot or sending sensor data wirelessly to a computer or phone.

To send a message from an Arduino board to a smartphone via Bluetooth, you would need to perform the following steps:

1. Connect the Arduino board to a Bluetooth module such as HC-05 or HC-06.
2. Write and upload a program to the Arduino board that can establish a Bluetooth connection with the smartphone. You can use the SoftwareSerial library to create a serial communication with the Bluetooth module.
3. Once the connection is established, the program should be able to send the message to the smartphone via the Bluetooth connection using the Serial.write() function.
4. On the smartphone side, you can use a third-party app such as “Serial Bluetooth Terminal” to receive the message sent by the Arduino board via the Bluetooth connection.
5. Test the system by sending a message from the Arduino board and verifying that it is correctly received and displayed on the smartphone app.

Purpose of this tutorial:

In this tutorial we will see how to send a message from Arduino to the smarthpone via bluetooth using the matrix keyboard. This is why we are going to create two programs: a mobile application with App Inventor for the smartphone and a program for Arduino.

To send a message from an Arduino board to a smartphone using a matrix keyboard, you would need to perform the following steps:

1. Connect the matrix keyboard to the Arduino board. The matrix keyboard typically requires multiple pins to be connected to the Arduino board for data and control.
2. Write and upload a program to the Arduino board that can read input from the matrix keyboard and store it in a string or buffer.
3. Connect the Arduino board to a Bluetooth module, such as an HC-06, and establish a Bluetooth connection with a smartphone or other Bluetooth-enabled device.
4. Write and upload a program to the Arduino board that can send the message stored in the string or buffer to the smartphone via the Bluetooth connection.
5. Use an app on the smartphone to receive the message sent by the Arduino board and display it on the screen.
6. Test the system by typing a message on the matrix keyboard and verifying that it is correctly received and displayed on the smartphone.

Necessary components

Arduino UNO

The Arduino UNO is a popular model of the Arduino open-source electronics platform. It is based on the ATmega328 microcontroller and has 14 digital input/output pins, 6 analog inputs, a 16 MHz quartz crystal, a USB connection, and a power jack. The UNO also has a built-in USB-to-serial converter, which allows it to be programmed and communicate with a computer via a USB cable. The Arduino UNO can be used for a wide variety of projects, including controlling LEDs, motors, and sensors, as well as communicating with other devices via Bluetooth, WiFi, or other wireless technologies. It’s an easy-to-use board that can be programmed using the Arduino IDE, and is a good option for beginners and experts alike.

HC-06 Bluetooh module

The HC-06 Bluetooth module is a small, low-cost device that can be used to add Bluetooth functionality to a wide range of electronic devices. It is a slave-only device, meaning it can only connect to other Bluetooth devices, and cannot initiate connections itself. It is commonly used in DIY projects, such as adding wireless control to a robot or remote control to a device. It can be easily interfaced with microcontrollers such as Arduino and Raspberry Pi, and communicates via serial communication.

4×4 matrix keyboard

A 4×4 matrix keyboard is a type of keypad that consists of 4 rows and 4 columns of buttons, for a total of 16 buttons.

The matrix keyboard works by connecting each button in a row to a common row pin on the microcontroller and each button in a column to a common column pin on the microcontroller. By scanning the rows and columns, the microcontroller can determine which button has been pressed.

When a button is pressed, it creates a connection between a row and a column, allowing current to flow between the two. The microcontroller can detect this change in state by reading the voltage on each row and column pin, and then determine which button has been pressed.

This type of matrix keyboard is commonly used in DIY projects and hobbyist applications, as well as in some commercial products. It’s relatively inexpensive and easy to interface with a microcontroller. They can be easily connected to a microcontroller with a lead wire, and the microcontroller can read the input of the button pressed.

This type of matrix keyboard can be used in a variety of projects, such as creating a calculator, a simple game or even a musical instrument.

Test plate

A test plate is a type of device used in robotics to test the functionality and performance of various components or systems. It is typically a physical platform or structure that is designed to hold and support various test items or devices, such as sensors, actuators, motors, or other types of mechanical or electrical components. Test plates can be used to simulate different environments or conditions, such as temperature, humidity, vibration, or other factors, in order to evaluate the performance of the components or systems being tested. They can also be used to perform a variety of diagnostic or diagnostic tests, such as stress testing, endurance testing, or other types of evaluations.

Connecting wires

Mounting

Program

Here is the program that allows you to connect the Arduino board to the smartphone and send a message by bluetooth using the matrix keyboard.

Creation of the application with App Inventor:

We are going to create a mobile application named ‘receive_arduino’ with App Inventor which allows you to receive a message from the Arduino board.

We propose to create the design of the application, with the following visual:

Programming with App Inventor

To program the application, App Inventor offers us to use the Blocks space, which allows you to create a program in the form of a block diagram. Very easy to use but requiring a little programming logic.

Here is the program of the application created in the Blocks area of ​​the Inventor App: