Embedded Programming: ESP32

ESP-IDF is what Espressif uses internally. It gives you full access to Wi-Fi, BLE, OTA, secure boot, partition tables, and the dual-core FreeRTOS scheduler. Arduino-ESP32 is a wrapper around ESP-IDF with limitations.

OTA firmware updates, flash encryption, secure boot v2, and partition management. These are not optional extras; they are what separates a prototype from a product. Lessons 7 and 8 cover them in depth.

Dual-core with FreeRTOS SMP, full Wi-Fi stack (STA/AP/mesh), BLE 4.2/5.0, and MQTT/HTTP client libraries. All running concurrently. The ESP32 is a complete IoT platform on a single chip.

MQTT brokers, REST APIs, phone apps via BLE, web dashboards. Each lesson connects the ESP32 to something new. By the capstone, you have a complete sensor network.

ESP-IDF Toolchain and Dual-Core Architecture. Install ESP-IDF, understand menuconfig, partition tables, and the dual-core FreeRTOS model. Build an RGB mood lamp where one core runs color animations and the other handles serial commands. Build: RGB mood lamp. Parts: ESP32 DevKitC, RGB LED (common cathode), resistors.

GPIO, Peripherals, and Driver Framework. Explore the GPIO matrix, LEDC PWM controller, pulse counter (PCNT), and RMT peripheral. Build a capacitive touch lamp dimmer using the ESP32’s built-in touch pins. Build: Capacitive touch lamp dimmer. Parts: Bright LED or small LED strip.

Wi-Fi and Network Configuration. Master the Wi-Fi driver: STA/AP/STA+AP modes, event model, SmartConfig provisioning, and scan capabilities. Build a Wi-Fi signal mapper that scans nearby access points and serves results as a webpage. Build: Wi-Fi signal mapper. Parts: No new parts.

HTTP Server and REST API. Build an HTTP server with RESTful endpoints, JSON parsing, mDNS discovery, and a responsive web UI served from SPIFFS. Build a browser-controlled thermostat with real sensor input. Build: Browser-controlled thermostat. Parts: DHT22 temperature/humidity sensor, relay module.

MQTT and Cloud Communication. Implement MQTT with QoS levels, TLS encryption, persistent sessions, and last will messages. Build a plant soil moisture monitor that sends alerts to your phone via a free MQTT broker. Build: Soil moisture monitor with alerts. Parts: Capacitive soil moisture sensor.

Bluetooth Low Energy. Implement GAP and GATT: advertising, scanning, services, characteristics, notifications. Handle BLE and Wi-Fi coexistence. Build a BLE environmental beacon that any phone can read. Build: BLE environmental beacon. Parts: Reuse DHT22.

OTA Updates and Secure Boot. Configure OTA partition schemes, implement firmware rollback, enable flash encryption and secure boot v2, and sign firmware images. Build a remotely updateable sensor node. Build: OTA-updateable sensor node. Parts: Reuse existing.

Power Management and Deep Sleep. Master deep sleep modes, ULP coprocessor programming, RTC memory persistence, and multiple wake sources. Build a solar-ready weather node optimized for months of battery life. Build: Solar-ready weather node. Parts: 2xAA battery holder.

Connected Sensor Network Project. Combine everything: build a two-node system with an outdoor sensor (battery, deep sleep, MQTT publish) and an indoor display (OLED, always-on, MQTT subscribe). A complete IoT deployment. Build: Two-node sensor network. Parts: SSD1306 OLED (or reuse from prior courses).