What Is an MCU?

What Is an MCU?

A microcontroller (MCU) is the heart of almost every electronic device: they’re essential to the operation of cell phones, refrigerators and washers, the flashing lights on children’s toys – you name it. Essentially, MCUs are the brains behind these devices, receiving inputs from their peripheral circuitry, such as sensors and switches; and controlling them in accordance with pre-programmed instructions.

Traditionally, MCUs have stored their program instructions in non-volatile memory modules such as ROM (read-only memory). Once the power is on or reset, the CPU fetches the first instruction found at address 0000, decodes it and executes it. At the same time, the program counter advances to 0001. The next instruction is then read at a higher program address by the CPU (address 0002). This instruction is decoded and executed. The program counter is then incremented again.

More recently, many MCUs have used built-in flash memory to store their program instructions. This technology allows MCUs to retain their program data even when the power is off, and it can be overwritten at any time. In addition, some MCUs also use SRAM (static random-access memory) to store run-time variables. This memory has the advantage of offering faster access and does not require a periodic refresh like ROM.

Many embedded system developers create programs for MCUs using a programming language such as assembler or C. Once the program is written, it is loaded onto the MCU with a programmer tool. MCUs can be programmed to function in either CISC or RISC mode. CISC mode MCUs have more complex instruction execution, while RISC MCUs execute commands faster.

A MCU may also contain its own wireless connectivity, which is helpful for IoT applications. Alternatively, the MCU can be connected to a host processor that provides the necessary wireless capability.

Marvel fans know the Marvel Cinematic Universe is a shared universe, but how many people are aware of the multiverse that exists within the MCU? From the end credits of the latest Spider-Man film to the appearance of Kingpin in the mid-credits of Venom, Marvel is introducing us to other realms and characters.

This Marvel explainer breaks down how the MCU and the Multiverse relate to each other, bringing you up-to-date on what’s happening in Phase 4 of the MCU. With new heroes such as Black Widow, Captain Marvel and Loki, you’ll be ready to see how the events of Avengers: Endgame tie into the rest of this MCU-centric world.

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