How to Select a Microcontroller

There are many considerations when selecting a microcontroller for a device. With deadlines to adhere to and pressures to get to market, you could select the first microcontroller that roughly suits your needs. This is a mistake. You must make an informed decision.

It is essential the hardware and software engineers come together in unison to discuss the different levels of the system, flowchart and the block diagram. This will determine the type of microcontroller you will need, so you should not purchase a microcontroller until you have come to a mutual decision. Once you know what you need, you need to identify the best option for your needs.

List Your Required Hardware Interfaces

Write a list of external interfaces a microcontroller will be required to support, which will help you to select the right option.

Consider communication interfaces, which could include the following peripherals:

  • USB
  • I2C
  • SPI
  • UART

You should make an extra note if a microcontroller would be required to support a USB or Ethernet because this will significantly determine how much program space you will require.

The second interface will feature analog to digital inputs, digital inputs and outputs, PWMs and more. Both interfaces will determine the number of pins your microcontroller will require to operate successfully.

Assess the Software Architecture

You also must consider the software architecture to pick the right microcontroller. Your light or heavy processing needs will help you identify whether you need to choose an 8 MHz 8051 over an 80 MHz DSP. Don’t forget to make a list of all the software requirements.

For example, you will need to identify how long every task will take to run. You must, therefore, identify how much computing power you will need to for your microcontroller’s architecture and frequency capabilities.

Select the Right Architecture

Once you have identified the hardware interface and the software architecture, the product’s engineer should now have a basic understanding of the microcontroller required. It is important to identify whether the application can run successfully with 8-bit architecture or if you need to select 16 bit. However, a 32 bit AM core could provide the perfect solution.

However, in addition to identifying what you need straight away, you also need to identify what you might require in the future. For example, if you can just about get by with 8 bit, it might be best to pick a 16 bit microcontroller so you’re prepared for additional features in the future.

Identify Your Memory Requirements

It is better to opt for a microcontroller with too much RAM or Flash than to run out of the features. You should, therefore, make program space a top priority. The last thing you will want to do is reach the end of a design to discover you need double the amount of RAM or Flash. It’s better to start with too much because you can also lower the space within the same chip family. An engineer will be able to identify how much RAM or flash will be necessary for the application.

Start Your Microcontroller Search

Once you have a detailed understanding of exactly what you need from a microcontroller, you can begin your search. It is essential you visit a reputable supplier, who can also discuss any requirements you might have. You can also discuss your requirements with a provider because they could help you discover an innovative new part that could be perfect for your device. Some suppliers may even have a search facility that will allow you to search for a peripheral set, power requirements and I/O.

The Power Requirements

You will probably come across a variety of microcontrollers that could be suitable. You should, therefore, take a look at the power requirements. For instance, if a mobile device is powered by a battery, it is vital you only select the microcontroller that suits your power requirements.

Now you have identified the best parts for the device, you will need to check its availability. The last thing you will want to do is purchase a bulk order of parts only to wait for three months for it to arrive, which will bring the process to a standstill. Also, it is up to you to identify how old or new the part is because a low price might be because the part will soon be out of production. You will, therefore, need the manufacturer to provide a guarantee that the part will still be in circulation in 10 years’ time.

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