Sean
Firmware is a software program that is hardcoded into the non-volatile memory of a microcontroller. It controls the hardware device that the MCU is attached to and brings it to life. It is the one and only program controlling the hardware device, and it is always running. A Fitbit for example, has firmware on an MCU controlling all aspects of the watch. It doesn’t have an operating system.
Firmware controls the hardware through a microcontroller. A microcontroller consists of the following components, which all usually reside on a single, small, green electronic circuit board:
- A processor or CPU (the engine)
- Memory
- Non-volatile memory (stores the program, or brains) – This is the program memory where the firmware program is stored. It doesn’t get lost when the power on the device is turned off. The instructions of the firmware program are executed by the CPU.
- Volatile memory (memory) – This stores data that the firmware uses while operating the hardware.
- I/O peripheral controls (connections to the different hardware subsystems) – For things like a display or bluetooth
