An embedded system is built from a small set of hardware components (processor, memory, input and output devices, communication interfaces, timing and power circuits) and the software that runs on them. Every embedded product, from a coffee machine to a flight computer, is some combination of these blocks. Knowing what each one does, and why it is chosen, is what lets an engineer read a schematic, write firmware and debug hardware.
Hardware components
1. Processor
The component that executes the firmware. Options are a microcontroller (CPU with memory and peripherals on one chip), a microprocessor or application processor (needs external memory, runs an OS), a digital signal processor, a system-on-chip combining several of these, or an FPGA. The choice sets the software environment, power and cost for the whole design. See microcontrollers in embedded systems.
2. Memory
- Program memory (non-volatile): flash, EEPROM or ROM holds the firmware and survives power-off. On microcontrollers it is on-chip; larger systems use external NOR/NAND flash or eMMC.
- Data memory (volatile): SRAM on-chip for variables, stacks and buffers; external DRAM on processor-based systems.
- Configuration and logging storage: EEPROM, a flash region or an SD card for settings and data that must persist.
3. Input devices and sensors
Switches and keypads, touchscreens, and sensors for temperature, pressure, humidity, light, acceleration, rotation, position (GPS), current and voltage, sound and images. Analog sensors connect through an analog-to-digital converter; digital sensors talk over I2C, SPI or UART.
4. Output devices and actuators
LEDs and displays (segment, character LCD, graphic TFT, OLED), buzzers and speakers, motors (DC, stepper, servo, BLDC) through driver circuits, relays and solid-state switches, heaters, valves and solenoids. PWM outputs and DACs provide analog-like control.
5. Peripheral interfaces
| Interface | Use |
|---|---|
| GPIO | Simple digital inputs and outputs |
| ADC / DAC | Reading analog sensors; generating analog outputs |
| Timers / PWM | Delays, periodic events, motor and LED control, input capture |
| UART | Serial console, GPS and modem links |
| SPI | Fast links to displays, flash, sensors |
| I2C | Low-speed sensor and EEPROM bus with few wires |
| CAN / LIN | Automotive and industrial networks |
| USB, Ethernet | Host connectivity and networking |
| Wireless (BLE, Wi-Fi, Zigbee, LoRa, cellular) | IoT connectivity; see embedded systems and IoT |
6. Clock, reset and supervision
A crystal or internal oscillator provides the system clock; a PLL multiplies it. A reset circuit holds the processor in reset until power is stable. A watchdog timer resets the system if the firmware stops responding. Brown-out detection prevents operation at an unsafe voltage.
7. Power supply
Regulators (linear or switching) that produce the voltages the chips need, a battery and charger in portable devices, power sequencing for multi-rail processors, and the sleep and wake circuitry that determines battery life. In many designs the power subsystem is the hardest part.
8. Debug and programming interface
JTAG or SWD pins and a header for the debug probe, often with a UART console. Without it, firmware development is blind.
9. Printed circuit board and enclosure
The PCB carries all of the above; its layout affects signal integrity, EMI and thermal behaviour. The enclosure handles heat, moisture, vibration and user access.
Software components
- Boot code / bootloader: sets up the processor and either starts the application or loads an operating system; supports firmware updates.
- Device drivers and hardware abstraction layer: code that configures and operates each peripheral.
- Operating system: optional; an RTOS or embedded Linux providing tasks, scheduling and services. See embedded operating systems.
- Middleware and stacks: communication protocols, file systems, graphics, security libraries.
- Application firmware: the device’s actual function, usually structured as state machines and control loops.
How these layers are arranged, and the block diagram that connects the hardware, is covered in embedded system architecture.
A real example: a smart thermostat
- Processor: Wi-Fi microcontroller with Cortex-M core.
- Memory: 4 MB on-chip flash, 512 KB SRAM; an external EEPROM for settings.
- Inputs: temperature and humidity sensor on I2C, capacitive touch buttons, a PIR occupancy sensor on GPIO.
- Outputs: a small TFT display on SPI, relays driving the heating and cooling circuits.
- Interfaces: Wi-Fi to the home router, UART for a debug console.
- Clock and supervision: 40 MHz crystal, watchdog enabled.
- Power: 24 V AC from the HVAC system, rectified and regulated to 3.3 V, with a supercapacitor for brief outages.
- Software: RTOS with tasks for sensing, control, display and cloud communication over MQTT; a bootloader that supports signed over-the-air updates.
How the components are chosen
Requirements come first: what must be sensed and controlled, how fast, how accurately, over what interfaces, on what power budget, at what cost and volume. The processor is then chosen for its peripherals and memory, the sensors and actuators for the physical task, the power supply for the source available, and the software stack for the processor and the timing needs. Read characteristics of embedded systems for the constraints that drive these choices.
Learn by building
Our embedded systems course works through each of these components with real boards, sensors and protocols, and the embedded project ideas list gives you systems to build end to end.
Frequently asked questions
What are the main components of an embedded system?
A processor, program and data memory, input sensors and devices, output actuators and displays, peripheral and communication interfaces, clock and reset circuits, a power supply, a debug interface, and the firmware (boot code, drivers, optional OS, application) that runs on them.
What is the difference between hardware and software components of an embedded system?
Hardware is the physical processor, memory, sensors, actuators and interfaces on the board; software is the firmware stored in memory that makes the hardware do its job.
Which memory is used in embedded systems?
Flash for the program and persistent data, SRAM for working data, and sometimes EEPROM for settings; larger systems add external DRAM and eMMC or SD storage.
What is a watchdog timer?
A hardware timer that resets the system if the firmware fails to service it within a set time, recovering from software hangs automatically.
Do all embedded systems have an operating system?
No. Many run bare-metal firmware with a main loop and interrupts; an RTOS or embedded Linux is added when several tasks or rich services are needed.
Share your question in comments or talk to our mentor team for batch guidance.
Ask the Admin Team
Drop your basic question in comments: eligibility, prerequisites, tools, fee range, and placement support.
Our team reviews and responds regularly.