LIBRARYWhat is a microcontroller?

A microcontroller is a whole small computer on a single chip: a processor, its memory, and a set of built-in peripherals, all on one piece of silicon. It runs one program, on its own, to sense and control the physical world. The ESP32 on a One Thousand Drones board is a microcontroller, and this whole library is about getting the most out of one.

What is on the chip?

Four things share the die. The CPU executes your program. RAM is fast working memory that holds variables while the chip runs, and forgets everything at power-off. Flash is non-volatile memory that stores the firmware, so the program survives a power cycle. And the peripherals are dedicated hardware blocks for talking to the world: GPIO pins, an ADC, timers, and serial buses. A desktop computer spreads those across many parts; a microcontroller puts them on one chip.

How is it different from a PC processor?

A PC processor is one part of a large system, with separate RAM sticks, a separate drive, and an operating system sitting between your program and the hardware. A microcontroller integrates its memory and peripherals on-die, runs a single program directly on the metal, starts in milliseconds, and sips power measured in milliamps. It trades raw speed for integration, real-time control, and low power, which is exactly what a small connected device needs.

Bare-metal or an RTOS

Firmware runs one of two ways. Bare-metal means your code is the only thing running, usually one endless loop. Or it runs on a small real-time operating system (an RTOS) that schedules several tasks and juggles them. The ESP32's default framework ships FreeRTOS, so even a simple program runs as a task under it, which is worth knowing the first time you meet a task or a delay call.

On a One Thousand Drones L1.01 board the ESP32-S3 module is the whole computer. Everything else on the board just feeds it power and breaks its pins out to headers you can wire to.