Operate · Embedded Control
Introduction to Microcontrollers
Introducing the programmable hardware used to connect sensors, execute control algorithms and generate outputs for physical actuators.
Contents
Key Learning Outcomes
By the end of this section, you should be able to:
01 Explain the role of a microcontroller within an embedded control system.
02 Identify the principal hardware features of the Arduino Uno R3, including its processor, memory and I/O connections.
03 Distinguish between digital input/output, analogue input and pulse-width modulation (PWM).
04 Explain how sensors, control algorithms and actuators can be connected through a microcontroller.
Introduction to Microcontrollers
A microcontroller is a compact programmable computing device designed to interact directly with physical hardware. It combines a processor, memory and input/output interfaces so that measurements can be acquired, processed and used to generate output signals.
Within a control system, the microcontroller can provide the link between the measurement devices, control algorithm and actuators introduced previously. Sensor measurements are received as inputs, the programmed algorithm processes this information, and output signals are generated to influence the physical system.
A simple embedded-control sequence is: measure → process → decide → actuate.The objective at this stage is not to study microcontroller architecture in detail, but to understand how a programmable device can connect the sensing and actuation elements of a practical control system.
Arduino Uno
The Arduino Uno R3 is used here to demonstrate the application of a microcontroller board. It provides a low-cost platform for connecting inputs and outputs, such as sensors and actuators, and for executing a control algorithm on embedded hardware.
The board is based on the ATmega328P microcontroller, which executes the user program and manages the board's input/output operations. The Uno operates at 5 V and can be powered through its USB connection or from an external supply through the VIN pin or barrel jack.
The board provides 14 digital input/output pins, six of which support pulse-width modulation (PWM), together with six analogue inputs. These interfaces allow a range of sensors and actuators to be connected for embedded measurement and control activities.
Figure 1: Key Components of the Arduino Uno Microcontroller. Hardware Overview
The numbered labels in Figure 1 identify the main connections and hardware features used throughout the practical activities.
ID Component Properties 1 Microcontroller ATmega328P 2 Power supply pins 5 V and 3.3 V regulated outputs 3 Voltage in (VIN) 7–12 V recommended external input 4 External power supply DC barrel jack or VIN pin 5 USB connection USB Type-B for power and programming 6 Digital input/output (I/O) pins 14 digital pins; 6 support PWM output 7 Digital ground Common ground (GND) 8 Analogue reference pin AREF 9 Analogue input pins 6 inputs (A0–A5) 10 Ground pins (GND) Multiple GND connections 11 Reset pin Active-low reset 12 Reset button On-board manual reset Operating and Electrical Characteristics
The Arduino Uno R3 is designed for a 5 V operating voltage. When an external supply is used through VIN or the barrel jack, 7–12 V is the recommended input range. Each digital I/O pin should normally be designed around a recommended operating current of 20 mA.
Program code is stored in 32 KB of Flash memory, 2 KB of SRAM is available for variables during execution, and 1 KB of EEPROM provides non-volatile storage. The ATmega328P on the Uno R3 operates at 16 MHz.
Operating voltage 5 VInput voltage (recommended) 7–12 VInput voltage (limits) 6–20 VDigital I/O pins 14PWM-capable digital pins 6Analogue input pins 6Recommended current per I/O pin 20 mA3.3 V pin current 50 mA max.Flash memory 32 KBSRAM 2 KBEEPROM 1 KBClock speed 16 MHzInteresting Resources
The following resources provide useful support for exploring the Arduino Uno, microcontroller I/O and model-based implementation in more detail.
Explore resource ↗UNO R3 Documentation
Arduino. Official board documentation with the pinout, datasheet, schematics and technical information for the Uno R3.
Explore resource ↗Built-in Examples
Arduino. Introductory examples covering digital input/output, analogue measurement, buttons, LEDs, PWM and serial communication.
Explore resource ↗Arduino Hardware
MathWorks. Simulink support for creating, running and deploying models on Arduino hardware, including sensor and actuator I/O.
Explore resource ↗ATmega328P
Microchip. Technical information for the microcontroller used on the Uno R3, including memory, I/O, ADC and peripheral capabilities.
Concluding Remarks
Microcontrollers provide an important connection between control-system theory and physical implementation. They allow information from sensors to be acquired and processed before generating output signals that can influence actuators and the physical process.
The Arduino Uno R3 provides an accessible platform for introducing these ideas. Its ATmega328P microcontroller, digital I/O, analogue inputs and PWM-capable outputs allow a range of sensors and actuators to be connected to a programmable controller.
At this stage, the important idea is to recognise the microcontroller as the hardware on which the measurement, decision-making and control functions of an embedded control system can be implemented.
