ESP32 — Development & Training Guide
Last reviewed: 2026-05-29
The ESP32 is a low-cost, low-power system-on-chip (SoC) microcontroller with integrated Wi-Fi and Bluetooth, developed by Espressif Systems. It's widely used in IoT projects, embedded systems prototyping, and production devices.
Overview
The ESP32 is a dual-core Xtensa LX6 CPU running at up to 240 MHz, with 520 KB of SRAM, integrated 802.11 b/g/n Wi-Fi, Bluetooth 4.2 (BR/EDR + BLE), and a rich set of peripherals (SPI, I²C, I²S, UART, ADC, DAC, PWM, Hall sensor, temperature sensor). It's Arduino-compatible via the Arduino-ESP32 core and also fully supported in PlatformIO and ESP-IDF (Espressif's native SDK).
Training Content
Display — ST7789 TFT (240×240)
A key hands-on project: connecting a 1.3" 240×240 IPS TFT display with ST7789 controller to the ESP32 via SPI.
Pin roles:
| Signal | ESP32 GPIO | Function |
|---|---|---|
| VCC | 3.3V | Display logic power |
| GND | GND | Ground |
| BLK | 3.3V | Backlight (HIGH = on) |
| SCK | GPIO18 | SPI Clock |
| MOSI | GPIO23 | SPI Data out |
| DC | GPIO15 | Data/Command select |
| RST | GPIO27 | Hardware reset |
| CS | Not used (always selected) |
Key concepts: - SPI communication: ESP32 acts as master, clocks data out on MOSI with SCK - The DC pin differentiates commands from pixel data - No CS pin — display is permanently selected - Correct SPI mode (MODE 3) is critical - Adafruit_ST7789 + Adafruit_GFX libraries handle command sequencing
Wiring caution: Avoid GPIO12, GPIO0, GPIO2 as they affect boot mode. The pinout above uses all safe GPIOs.
MQTT IoT Telemetry Pipeline
Training content covers an end-to-end IoT pipeline using: - ESP8266/ESP32 as the sensor node - BMP280 temperature/pressure sensor - Mosquitto MQTT broker - Python subscriber on the backend
Architecture: Sensor → ESP32 → Wi-Fi → MQTT Broker → Python subscriber → data processing.
Servo Motor Control
A servo motor controlled via a rotary angle sensor on the ESP32: - Uses PWM (LEDC peripheral) to drive servo - Rotary sensor (potentiometer) read via ADC - Mapping sensor values to servo angles (0–180°)
Additional Resources
- PlatformIO Adafruit_ST7789 — Library installation guide for PlatformIO and Arduino IDE
- Wemos D1 Mini pinout reference
- AZ281 display datasheet (French)
Why ESP32?
- Built-in Wi-Fi/BT — no external modules needed
- Dual-core — run networking on one core, application on the other
- Deep sleep — microamps in sleep mode for battery-powered projects
- Arduino + PlatformIO — beginner-friendly toolchain
- ESP-IDF — production-grade SDK for advanced use
- Rich peripheral set — enough for most IoT and embedded projects
Getting Started
- Install PlatformIO in VS Code (or Arduino IDE + ESP32 board package)
- Wire your ESP32 to the ST7789 display using the pin table above
- Install Adafruit_ST7789 and Adafruit_GFX libraries
- Run a basic sketch that fills the screen with color
- Progress to text rendering, shapes, and sensor data display
Pin Safety Reminder
Some ESP32 GPIOs affect boot behavior: - GPIO0 — boot mode select (pull low for flash mode) - GPIO2 — strapping pin, must be high for normal boot - GPIO12 — flash voltage selection - GPIO15 — strapping pin (also used here for DC — safe post-boot)
Always use safe GPIOs for display and sensor connections.