Interfacing Devices in Microcontrollers

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Microcontrollers are the fundamental components of all modern electronic devices and embedded systems. They allow these electronic devices and systems to interact with the external world by processing signals from sensors, keypads, displays, or other communication modules. These intermediate devices that enable interaction between microcontrollers and the external world are termed as interfacing devices.

In this chapter, we will learn where and how interfacing devices are used with microcontrollers.

What is an Interfacing Device?

In case of microcontrollers, some external devices are connected with microcontrollers to perform specific tasks or functions, and these external devices are called as interfacing devices. For example, in a pin-based security system, a numeric keypad act as an interfacing device with an internal microcontroller of the system and allows for entering and verifying security pin.

Interfacing devices are important components of a microcontroller-based system as they process data transferred between a microcontroller and external peripherals. Some common examples of interfacing devices used with microcontrollers include −

• Keypads and Keyboards
• Analog-to-Digital Converters
• LCD Displays
• Actuators like motors, relays, etc.
• Communication modules like Bluetooth, Wi-Fi, GSM, etc.

Let's discuss each of these microcontroller interfacing devices in detail.

Applications of Keypad Interfacing

A keypad or keyboard is one of the very common input devices. It consists of certain rows and columns of keys arranged in a matrix format. These interfacing devices are mainly used for inputting numeric and alphanumeric data into the microcontroller system.

A password-based lock system used in door or lockers is a common example where a microcontroller interfaced with a keypad is used.

The working of a typical password-based security system interfaced with keypad is explain here −

• Firstly, the user enters a pin or password using a keypad interfaced with a microcontroller.
• The microcontroller verifies the entered password against a stored value.
• If the password is correct, the microcontroller operates the unlocking mechanism, or if the password is incorrect, the operation of unlocking mechanism is blocked or an alarm is given to security personnel.

Applications of Analog-to-Digital Converter Interfacing

Analog-to-digital converter, also called as ADC, is an electronic system that converts analog signals into digital signals. It is required in microcontroller-based systems for interfacing process. This is because many external world signals like temperature, pressure, sound, or light are originally analog signals, while microcontrollers can process only digital signals. Therefore, ADC becomes essential for interfacing between the microcontroller and external peripherals.

A real-world example of ADC interfaced microcontroller is a SCADA system used in industrial automation for remote monitoring and control of industrial processes.

The working of a typical temperature monitoring system making the use of ADC with microcontroller is explained below −

• Temperature sensors measure the temperature of the system and produce an analog signal.
• The ADC receives and converts these analog signals into digital signals and send them to the microcontroller for further processing.
• The microcontroller processes this data and communicate to the relay.
• If the system temperature exceeds the threshold value, then the microcontroller operates the relay to either give an alarm or switch off the heaters.

Applications of LCD Display Interfacing

LCD stands for Liquid Crystal Display, it is one of the most widely used interfacing devices for visualization of text, numbers, or symbols. Microcontrollers with LDC display provide a lowpower, cost-effective, and user-friendly solution for interfacing between microcontrollers and the user.

An RFID-based attendance system is a common example of microcontroller interfaced with LCD display. This system provides a modern approach to record attendance of students or employees.

The following working of a typical RFID attendance system explains the application of LCD display interfaced with microcontrollers −

• Every student or employee is provided with an RFID card which stores his identification details.
• When the person swipes the card in the slot, the RFID reader of the system reads the data and sends to a microcontroller.
• The microcontroller compares the scanned values with stored values to verify the details and updates the attendance record accordingly.
• Finally shows the attendance status on an LCD display which is interfaced with the microcontroller.

Applications of Actuator Interfacing

Actuators are devices that convert electronic signals into physical actions or motions. These are basically output devices. Some examples of actuators include motors, relays, or solenoids. These are mainly employed in microcontroller-based automation systems.

A smart home automation system is a real-world example of actuator interfacing application. In this system, microcontrollers are interfaced with actuators to control the operations of home appliances, lighting, or security system from a remote place.

Applications of Communication Module Interfacing

Communication modules are another key interfacing devices used with microcontrollers. These devices allow microcontrollers to exchange data with other devices using a wired or wireless communication protocol. Some very common communication modules and their applications in microcontroller-based systems are given here −

• Bluetooth and Wi-Fi − These modules are mainly used in Internet of Things (IoT) devices.
• GSM and GPS − These communication modules are employed in vehicle tracking systems.
• RFID and NFC − These are used in access control systems.

Let's take a real-world example of an IoT-based smart agriculture system used for smart farming. This system makes use of communication modules like LoRa and Zigbee for communicating real-time agricultural data.

The working of this smart agriculture system is explained here −

• Firstly, different types of sensors collect data related to soil moisture, temperature, and humidity.
• Then, a microcontroller processes this data and sends to a cloud platform using a wireless communication protocol.
• Finally, farmers can monitor and control the irrigation system using a smartphone application.

Conclusion

To conclude, interfacing devices play an important role in microcontroller systems in developing smart, automated, and efficient embedded systems.