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+---- Thread: Microcontrollers & Embedded Systems — How Real Devices Think and Act (/showthread.php?tid=362)
Microcontrollers & Embedded Systems — How Real Devices Think and Act - Leejohnston - 11-17-2025
Thread 7 — Microcontrollers & Embedded Systems
How Real Devices Think, Sense and Control the World
Microcontrollers power almost everything around you —
from washing machines and thermostats
to drones, cars, game controllers, and industrial robots.
This thread teaches the fundamentals:
what microcontrollers are, how they work, and how you can begin using them.
1. What Is a Microcontroller?
A microcontroller (MCU) is a small, self-contained computer built onto a single chip.
It typically includes:
• a CPU (processor)
• RAM
• flash memory
• input/output pins (GPIO)
• timers/counters
• ADC (analog-to-digital converter)
• communication modules (UART, I2C, SPI)
MCUs run compact programs that control real-world systems.
Famous examples:
• Arduino (ATmega328P)
• ESP32
• ESP8266
• STM32
• Raspberry Pi Pico (RP2040)
Unlike desktop computers, MCUs are built for one purpose —
to repeatedly perform specific tasks with reliability.
2. Microcontroller vs Microprocessor
Microcontroller (MCU):
• all-in-one chip
• designed for control tasks
• low power
• simple programs
• interacts directly with hardware
Microprocessor (CPU):
• requires external RAM/ROM
• used in PCs, phones
• high speed
• complex operating systems
If a device reacts to sensors or controls motors,
it likely uses a microcontroller.
3. The Architecture of a Microcontroller
Typical MCU internal structure:
• CPU — executes instructions
• Flash memory — stores your program
• SRAM — working memory
• EEPROM — long-term data storage
• GPIO ports — control external components
• Timers — generate precise delays
• ADC — convert analog voltage to digital
• DAC — convert digital to analog (some MCUs)
This tiny chip can manage an entire device on its own.
4. GPIO — Digital Inputs & Outputs
"General Purpose Input/Output" pins let the MCU communicate.
Digital output examples:
• turn an LED on/off
• control a motor driver
• send digital signals to other chips
Digital input examples:
• read a button
• read sensors
• detect logic signals
A GPIO pin is the microcontroller’s window to the world.
5. Timers, PWM & Controlling Motors
MCUs contain timers that allow:
• accurate delays
• event triggers
• Pulse Width Modulation (PWM)
PWM is used to:
• dim LEDs
• control servo motors
• control DC motor speed
• generate analog-like signals
Example PWM idea:
A 50% duty cycle = LED half brightness
A 10% duty cycle = LED dim
A 90% duty cycle = LED bright
6. Analog Inputs — ADC
Many sensors output analog voltages.
Examples:
• temperature sensors
• light sensors (LDR)
• potentiometers
• gas sensors
• microphones
An ADC converts voltage into a number the MCU can use.
Example:
10-bit ADC → value between 0 and 1023.
7. Communication Protocols (UART, SPI, I2C)
UART: simple serial communication (text, debugging)
SPI: fast, used for displays & flash memory
I2C: two-wire bus used for sensors
MCUs use these to talk to:
• gyroscopes
• accelerometers
• displays
• other microcontrollers
8. Real Examples of Embedded Systems
• drones using sensors + motor controllers
• thermostats reading temperature & switching relays
• robots tracking input and moving motors
• smart watches monitoring heart rate
• automotive control units
• home automation systems
Embedded systems run modern life.
9. Example Beginner Project (with Code)
Blink an LED — the “Hello World” of embedded systems
Arduino code:
Code:
void setup() {
pinMode(13, OUTPUT); // configure pin 13 as output
}
void loop() {
digitalWrite(13, HIGH); // turn LED on
delay(500);
digitalWrite(13, LOW); // turn LED off
delay(500);
}This simple program demonstrates:
• GPIO configuration
• digital output
• timing
• infinite loops
10. Intermediate Example — Read a Sensor
Analog temperature sensor (LM35):
Code:
int sensorPin = A0;
void setup() {
Serial.begin(9600);
}
void loop() {
int reading = analogRead(sensorPin);
float voltage = reading * (5.0 / 1023.0);
float temperatureC = voltage * 100;
Serial.println(temperatureC);
delay(500);
}Shows:
• ADC usage
• voltage conversion
• temperature calculation
• UART output
11. What You Can Build With MCUs
• robots
• RC cars
• drones
• weather stations
• security systems
• IoT devices
• cat/dog feeders
• automatic greenhouse controllers
• full home automation systems
The possibilities are endless.
12. Recommended Next Steps
• Thread 8 — Power Electronics & Motor Drivers
• Thread 9 — Digital Signal Processing Basics
• Thread 10 — Build Your Own Microcontroller Project
End of Thread — Microcontrollers & Embedded Systems