What Is an Embedded System?

This is one of the questions I get asked the most frequently. Half of the time my mother is the one asking (sorry Mom!), but the rest of the time, it’s being asked by a client. It’s almost always followed by: “Why is that going to take so long?” or “Why is that going to cost so much?” (or if it’s my mother “Is there any money in that?”).

It’s easy to assume that there’s a ‘simple answer’ but really, there isn’t. Embedded systems look and perform like a lot of things. We don’t see the vast majority of the embedded systems we interact with on a daily basis. We have to take a deeper look and pull back the ‘plastic curtain’ to get to the heart of what an embedded system is. Let’s do it in stages: ‘simple’, ‘less simple’, and ‘maybe too much detail’.

If, at any point, you decide you’ve heard enough of me rambling and want help building your embedded system, reach out to us at hello@ringtaillabs.com.

The Simple Explanation

Embedded Systems are the electronics, firmware, and software inside of the devices you interact with every day.

If that was unsatisfying, keep reading.

The Less Simple Version

Pick something you’ve interacted with today —  your electric kettle, your coffee cup, or the microwave that’s still heating up your breakfast burrito (it’s early when I’m writing this, can you tell?).

Here, we hit our first requirement to be an embedded system: it takes power.

So the coffee cup is out — but we still have the microwave and the kettle in the running. (Is your refrigerator running? If so, you better go catch it.)

If you asked five engineers which of these are embedded systems, you might get six different answers, and you’d definitely regret asking. Since you asked me, I’ll give you one question and let you come up with the answer: Is it doing more than turning off and on?

For me, this is the line between electronics and embedded systems. There has to be some level of ‘augmentation’ beyond a switch (that’s right, I’m saying your overhead lights are not an embedded system). An embedded system does some sort of processing.

In the case of the coffee maker, it waits for a button push (or two if yours is as complicated as mine) and outputs beautiful coffee by heating the water to the right temperature, dripping water until it’s gone, and then keeping the carafe hot. As another example, your microwave takes some really complex instructions (Anyone else have a ‘sensor’ button they don’t understand?) and yields, well, hot food.

So there you have it, the less simple definition of an embedded system: It’s a powered device that does some sort of processing.

Now I know you have more questions than you started with, so keep reading!

The Complicated Version

In practice, an embedded system is pretty easy to classify, and very difficult to specify. We did a good job with the basics above — its powered, it controls something, and its inside of something. Now we are going to dig into these and add one more: It’s a system.

It’s Powered

An embedded system is powered. It might be powered from the wall, a battery, or your car’s alternator, but at some point, it is taking in power. Usually, this involves filtering and regulating the power to ensure that everything inside the device performs in exactly the same way every time. The power makes heat, light, decisions, or something else entirely.

It has an Element of Control

Something in the device has to make decisions. It might be simple, like a 555 timer turning on your Christmas lights. It might be absolutely tiny, like the new SiLabs BG27. It could be insanely complex like, well, the new SiLabs BG27 running an RTOS and Dynamic Multi-protocol (I’m really dying for an excuse to put the BG27 into a product). There is an entire article to be written about what this control looks like and if it‘s hardware control, software control, or firmware control. There are entire books to be written on how to make this step efficient, performant, and safe. When it’s time to make these decisions, connect with Ringtail Labs! We’d love to help you make them.

It’s behind the ‘Plastic Curtain’

That ‘Plastic Curtain’ line in the first section wasn’t a throw away. Embedded systems are (almost) always hidden behind some kind of housing. In our cars they’re hidden behind the dash and under seats, but in ways that don’t interfere with their function. In our devices they’re under the keyboards, behind the screen, or under a pretty layer of plastic. These beautiful wrappings are the plastic curtain, and they augment the utility of these devices, enhance the beauty of them, or generally make their operation possible. That’s right — It’s a system.

It’s a System

Each of these elements has to be designed in careful harmony with the others to ensure it works as intended. You can’t connect your car battery directly to your cell-phone and expect good results. You can’t expect a microcontroller to know what you want it to do without adding firmware to it. This is the heart of an Embedded System — a system embedded in some housing that consists of hardware and software elements that work in harmony.

In the next article, I’ll talk about how to start the process of designing these intricate systems. For now, if you still have questions, need an expert, or better yet, a team of experts, please reach out at hello@ringtaillabs.com