8-bit vs. 32-bit MCU: Choosing the Right Microcontroller for Your PCB Design

March 5, 2018 CircuitStudio

Electronics connected throughout a home



I have very bad shopping habits when it comes to electronic gadgets. Torn between buying a new laptop or upgrading my tablet to an iPad Pro, I end up purchasing both and getting an endless lecture from my fiancé.


Thankfully, I’m more decisive when choosing between 8-bit and 32-bit microcontrollers for my hardware design. They’re not too different in terms of cost, and one is more powerful than the other. To make the right choice, however, it’s important to understand the fundamental differences between the two microcontrollers.


Strictly speaking, an 8-bit microcontroller processes 8-bits of data at any particular time. A 32-bit microcontroller can theoretically handle quadruple the amount of data, making it technically more efficient. However, deciding between an 8-bit and 32-bit mcu involves more than the data width alone. Considering the major differences between 8-bit and 32-bit microcontrollers will help you make the best decision for your design:

8-Bit vs. 32-bit MCU: Speed and Memory

One of the primary advantages of a 32-bit mcu over an 8-bit mcu is its superior processing speed. A typical 8-bit microcontroller usually runs at 8 Mhz while a 32-bit microcontroller can be clocked up to hundreds of Mhz. You might not notice the speed difference if you’re using the mcu to turn on a mechanical relay; however, it quickly becomes obvious when you’re running applications that require heavy data processing. For example, a door access controller that processes thousands of transactions per day requires a 32-bit microcontroller.


8-bit microcontrollers are cheap and easy to work with. In fact, they are still very popular after four decades in many applications. But if you’re working on a product that requires a huge internal Random Access Memory (RAM), then you may have to replace the 8-bit with a 32-bit. 32-bit microcontrollers often have 8 times more RAM than their 8-bit peers. If you need to a huge buffer to store audio data, then a 32-bit microcontroller is the better option.



Lines of light on a curving road

Get a 32-Bit microcontroller if your design can’t live without speed.


Adding Peripherals

The basics of embedded system design involve creating a list of required peripherals based on project requirements. If you require Ethernet, Universal Serial Bus (USB), multiple universal asynchronous receiver-transmitter (UARTS), and a Controller Area Network (CAN) bus, an 8-bit microcontroller would be insufficient. You might have to consider adding peripheral chips, which may cost more than a 32-bit microcontroller alone.


Generally, 32-bit microcontrollers are feature-packed compared to 8-bit microcontrollers. With superior processing speed, a 32-bit microcontroller can handle multiple peripherals efficiently. However, bear in mind that 32-bit microcontrollers consume more power, especially when all peripherals are turned on.

Hardware Design and Learning Curve

It’s fair to say that a PCB with a 32-bit microcontroller, which usually has over 100 pins, is more complex than an 8-bit one, which rarely exceeds 30. Assembly wise, soldering an SOIC package is definitely easier than a Quad Flat Package (QFP) or a Ball Grid Array (BGA) package. There are also fewer quality issues with wider pitches on an SOIC package. If an 8-bit microcontroller is sufficient for your project, do not choose a 32-bit microcontroller. Otherwise, use pre-built footprints in PCB design software to minimize your design time.


When you search programming tutorials for microcontrollers, you’ll find that most tutorials stick to 8-bits microcontroller like 8051 or Arduino, a popular 8-bit based microcontroller board. This is because it is easier to get started with an 8-bit microcontroller. A 32-bit microcontroller has a more complex architecture and demands a longer time for familiarization. If you’re creating a simple production counter, it’s not cost-efficient to ask the firmware engineer to explore microcontrollers for a week when he can set up the entire firmware for much cheaper using an 8-bit mcu.



Arduino board with 32-bit microcontroller

Expect a steeper learning curve with 32-bit microcontrollers. Editorial credit: goodcat / Shutterstock.com


Choose the Best MCU for Your PCB Design

To choose the best microcontroller for your PCB design while minimizing time and overall cost, it is necessary to carefully assess key advantages and disadvantages of 8-bit versus 32-bit microcontrollers. By taking design requirements like speed, complexity, peripherals, and memory into consideration, you can minimize decision paralysis as well as potential setbacks when choosing the best mcu for your design.


With a professional PCB design tool like Altium’s CircuitStudio, you can determine design requirements in advance while optimizing your learning curve.


Still undecided between an 8-bit or 32-bit microcontroller for your project? Talk to an expert at Altium.


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