The Difference Between SoCs and MCUs

Untangling SoCs from Microcontrollers

Some might say that computer technology is evolving and advancing at such a clipped pace that cables are crossing and terminology has become intertwined. To untangle some of the confusion, let’s take a closer look at the difference between a system on a chip (SoC) and a microcontroller (MCU).

Mighty Microcontrollers

If you brewed a cup of joe on a “traditional” coffee maker (read: Mr. Coffee) this morning, you likely encountered a few microcontrollers (MCUs) at work. An MCU is a compact, integrated, circuit with “a processor, memory and input/output peripherals on a single chip.” Also described as a “small, self-contained computer” on a “single integrated circuit or microchip,” microcontrollers control simple features or singular functions in a larger embedded system within a device. A single device, depending on its complexity, will likely have a number of microcontrollers that work in concert to perform various functions.

Microcontroller Components

• Central processing unit
• Programmable input/output
• Memory in the form of RAMROMflash

MCU Block Diagram

Image Credit: ResearchGate

Microcontroller Applications

Common applications of microcontrollers include home appliances; TVs and entertainment systems; medical equipment; office equipment; and air, water and spacecraft. However, it’s important to remember that all of the aforementioned devices will contain more than one—and more often than not, numerous—microcontrollers that each perform singular tasks. Each microcontroller then works in concert with its counterparts to aid in the overall function of the device.

Today, it’s common to find microcontrollers in connected home and business devices such as smart thermometers, doorbells and security systems. These are typically classified under Internet of Things or IoT devices. Each MCU within these devices performs a singular function and uses a feedback system to gather information and trigger responses, based on the programming.

Photo Credit: 1979 Texas Instruments Microcontroller by Christian Bassow

A Touch of Microcontroller History

The 1971 invention of the microcontroller is attributed to Gary Boone and a team at Texas Instruments, at a time when Intel was busy debuting the first microprocessor (MPU). The MCU they created was featured in Texas Instrument products for a couple of years before it was offered externally in 1974.

The inner workings of a smartphone. Image by ABDUL HAKEEM from Pixabay.

The Mightier SoC

If you opened a weather app on your smart phone while you were brewing coffee, you benefited from system-on-chip (SoC) technology. Your smart phone is capable of countless functions—opening and using the weather app is just one—and the SoC makes all of the features and functionality of the device possible. To put it simply, a system on a chip is an entire electronic or computer system on a single chip or integrated circuit designed to perform a wide array of functions. Systems on a chip require fewer raw materials than non-integrated counterparts, are more energy efficient to operate, and require less space.

SoC Components

• One or more central processing units
• Microcontrollers
• Numerous programmable input/output
• Digital signal processors
• Analog input/output
• Memory in the form of RAMROMflash
• Additional accelerators and supporting hardware

It is important to note that specific standards do not exist on SoC circuitry, however their components are more varied and greater in number than MCUs.

SoC Block Diagram

Image Credit: Jiri Gaisler

SoC Applications

The compact size of SoCs makes them ideal for portable device applications, such as smart phones; tablets; smaller, lightweight laptops; wearable health monitors; and digital cameras, as well as cars, to name a few.

SoC Origins

Not too far behind the invention of the MCU, the debut of the SoC soon followed in 1974 when the Microma Liquid Crystal (LCD) Digital Watch featured its entire electronic system on a SoC. It is said that when “digital signal processing (DSP) cores were integrated with regular CPUs, the innovators ended up with SoC.” Following the Microma digital watch, National and Texas Instruments introduced the electronic calculator as the next SoC application. Then, in the 1990s, SoC technology was applied to “hand-held games and instruments, as well as speech processing, data communications, and PC peripheral products.” These advancements were accomplished by embedding microcontrollers and digital signal processing cores into system-level chips.

MCUs and SoCs: A Side-by-Side Comparison

So, what’s the difference? MCUs and SoCs both sound like computers on a chip. While that overarching definition may be true, there is a clear difference on the components of the two chips and how much each is inherently able to do.