What is a microcontroller?

Are you a newly-hired salesperson who needs to sell microcontrollers but don’t have a clue about what it is?
Or, are you a freshman student who wants to have a grasp of what an MCU is before you decide your major?  Whether you are still in school or not, learning never ends. And it is never too late to learn new things 🙂 In this post, we’ll take a look under the hood of the microcontroller with the assumption that you have no previous knowledge.

So, what is a microcontroller (MCU)?

A MicroController Unit (MCU) is much like a Personal Computer (PC) only smaller; everything is integrated on a single chip called an integrated circuit (IC). MCUs are all around us: they are embedded in household appliances, toys, cars, cell phones, water and gas meters, alarm and security systems, health and fitness devices and much, much more. The MCUs usually fulfill a very specific role, often as a part of a larger system, which allows them to be tailored to fit the requirements of the application, whether it is functionality, reliability, power consumption or even price. Birthday cards with music is an example of a product that is very price sensitive – the added feature of music is only worth so much to the consumer.

Figure 1.1. An MCU with the pins exposed on the back side 

The typical household has usually at least ten times as many MCUs as PCs. Although PCs may be familiar programming ground to many, the MCU market is much larger and opens endless possibilities for innovation. Will you bring the next revolutionizing gadget to life? The continued progress in the MCU industry requires dedicated and talented people developing both the MCUs as well as the end products they are embedded in; there should be plenty of interesting opportunities.

Then, what does an MCU consist of? 

An MCU typically consists of a Central Processing Unit (CPU), memory, Input/Output (I/O) and other external modules (peripherals) like Analog to Digital Converters. An MCU product line usually consists of many different models, each with its own set of functionality and peripherals. An MCU vendor might design all the components of an MCU themselves or buy designs from others. The designs are referred to as Intellectual Property (IP).

All the components of the MCU are combined into a single Integrated Circuit (IC). A batch of a few hundred MCUs can be manufactured on a single slice of semiconductor material called a wafer. The MCUs are then divided and packaged in small plastic containers, which only reveals the pins of the microcontroller, see Figure 1.1.

MCU vs. PC 

MCUs are smaller than PCs, both in term of physical size, performance and cost. This allows them to be used in countless applications not suited for PCs, but it also imposes many restrictions. Programmers coming from PCs might not have ever cared about code size or power consumption, both of which are very important concerns when developing programs for MCUs. When the application is running on battery power and the device is cost sensitive, minimizing power consumption and storage requirements
might be more important than execution speed. Furthermore, reliability and responsiveness is important. Programmers used to floating point operations are not likely to find any support for this in hardware – Floating Point Units (FPUs) are not common. The architecture otherwise might also be totally different from the ones used by PCs. An executable produced on your PC is highly unlikely to run on an MCU, and while PCs use operating systems to handle hundreds of programs and processes, some MCUs only
run a single program at a time, others run some kind of operating system aimed at MCUs including Real Time Operating Systems (RTOS).

In the next post, we will know more about the MCU peripherals.

Energy Micro University is a program developed by Energy Micro to encourage learning and to help institutions develop their own programs for teaching microcontroller development. To download learning materials in pdf, please click here: Energy Micro University Program

For technical questions about this project, please use our support forum