Unit 2 Summary
| Lesson | Topic | Key content covered |
|---|---|---|
| Lesson 2.1 | Role of microcontrollers in IoT | MCU architecture, MCU vs MPU vs SBC, power consumption, execution cycle, serial communication protocols. |
| Lesson 2.2 | Arduino and ESP32 configuration | Board specifications, pinout reference, IDE setup, digital I/O, PWM, debounce, Wi-Fi connection code. |
| Lesson 2.3 | Analog and digital signals | Signal types, ADC resolution, conversion formula, LDR circuit, ESP32 ADC limitations, DAC, Serial Monitor debugging. |
Quick Reference — Key Functions
| Function | Board | Purpose |
|---|---|---|
| pinMode(pin, mode) | Both | Configure a pin as INPUT, OUTPUT, or INPUT_PULLUP |
| digitalWrite(pin, HIGH/LOW) | Both | Set a digital output pin HIGH or LOW |
| digitalRead(pin) | Both | Read a digital input pin (returns 0 or 1) |
| analogWrite(pin, 0–255) | Uno only | Output PWM on a ~-marked pin |
| analogRead(pin) | Both | Read analog voltage (0–1023 Uno, 0–4095 ESP32) |
| ledcSetup(ch, freq, res) | ESP32 | Configure a PWM channel |
| ledcAttachPin(pin, ch) | ESP32 | Attach a GPIO pin to a PWM channel |
| ledcWrite(ch, duty) | ESP32 | Set PWM duty cycle on a channel |
| dacWrite(pin, 0–255) | ESP32 | True analog output on DAC pins (GPIO 25 or 26) |
| Serial.begin(baud) | Both | Initialise serial communication (9600 or 115200) |
| millis() | Both | Return milliseconds since power-on (non-blocking timing) |
| map(val, f1, f2, t1, t2) | Both | Rescale a value from one range to another |
| WiFi.begin(ssid, pass) | ESP32 | Connect to a Wi-Fi network |
| WiFi.localIP() | ESP32 | Return the device’s IP address after connection |
Key Terms Glossary
ADC
Hardware that converts a continuous analog voltage into a discrete digital number.
Analog signal
A signal that varies continuously within a range of values.
Bootloader
Small program stored in MCU flash that initialises hardware and loads the user program.
DAC
Hardware that converts a digital number into a proportional analog voltage.
Deep sleep
Low-power MCU state where most circuits are off; uses µA of current.
Debounce
Technique to prevent multiple false readings from a single mechanical button press.
Digital signal
A signal with only two valid states: HIGH (logic 1) or LOW (logic 0).
Duty cycle
The percentage of one PWM period during which the signal is HIGH.
EEPROM
Electrically Erasable Programmable Read-Only Memory — non-volatile storage for configuration.
GPIO
General Purpose Input/Output — programmable digital I/O pin on a microcontroller.
I2C
Inter-Integrated Circuit — two-wire serial protocol (SDA + SCL) for connecting sensors.
MCU
Microcontroller Unit — a complete computing system on a single chip.
PWM
Pulse Width Modulation — digital technique to simulate analog output by varying on-time.
SRAM
Static RAM — fast volatile memory used for variables and the program stack.
SPI
Serial Peripheral Interface — fast four-wire serial protocol for sensors and displays.
UART
Universal Asynchronous Receiver-Transmitter — two-wire serial port (TX/RX).
Further Reading & Resources
- Arduino Language Reference — docs.arduino.cc/language-reference
- ESP32 Arduino Core Documentation — docs.espressif.com/projects/arduino-esp32
- ESP32 Pinout Reference — randomnerdtutorials.com/esp32-pinout-reference-gpios
- Tinkercad Circuits (free, browser-based) — tinkercad.com
- Wokwi Simulator — wokwi.com — free browser-based Arduino and ESP32 simulator with Wi-Fi simulation support
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