JavaScript on Microcontrollers

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Hi, I’m Niels.

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I’m Dutch. I’m from the Netherlands.

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Or as you call it Stag-party-drink-beer-smoke-weed-red-light-district-zone. That is fine. Absolutely fine. We love the British.

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The only thing is that whenever I fly to London there are always cannabis dogs waiting for us at the airport upon arrival. Except for this time. I flew into London City Airport and there were no extra checks at all. Of course plane was full of bankers. Up standing citizens. They don’t smoke weed…. They use cocaine.

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So who was here two years ago? As Dylan mentioned, two years ago I did a talk here. About WebBluetooth and all of the demo’s failed. And Yes, this is my heartbeat before the talk knowing that the demos are not working. So I am back. This time with a little safer subject. Not going to take risks. I’m not doing hardware demo’s this time…. I’m livecoding hardware demo’s instead. What can go wrong?

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I am a Mozilla Tech Speaker, Google Developer Expert.

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I tweet at @html5test

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I love the web. I’ve been a web developer since 1994. I written my first HTML 25 years ago. Yes I am old. I love HTML, I love CSS and I even love JavaScript. Okay, grown to love it.

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And I love electronics. When I was a teenager I had this cardboard electronics set with all kinds of different components…

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And you could connect them together with clipping wires between some springs. You could build a radio or even a transmit morse code.

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And this is what I have now. Still some components to connect together with some wires. But the components have become much more advanced. Instead of transistors and diodes and resistors, we now play with microcontrollers and all kinds of sensors. And everything works together.

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I know some of you are thinking, why should I care about this? I am a web developer, I don’t have anything to do with electronics. And you’re right.

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But when you connect devices to the web you get the Internet of Things. You get devices that talk to servers, and even directly to browsers. And there things start to get interesting for web developers.

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The main issue I’ve seen when web developers start playing with microcontrollers and IoT is the barrier of having to lean C. Now C and Javascript may look quite similar syntacticly, but is a completely different beast.

You not only need to learn C, but also low level programming concepts like memory management and pointers. Even though I learned this back in school 25 years ago, I hate this.

What if we could just use a language that we already know? What if we did not need to worry about those low-level concepts?

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What if we could JavaScript on Microcontrollers? And not only that, what if we could leverage the browser to connect to these microcontrollers and let them extend each others capabilities.

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This is all fine and well, but…..

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Microcontrollers are slow. They are really slow. And when I say slow, that really does not convey the idea how slow they actually are. They are slooooooooow. Take for example the slowest computer you can buy today. The Raspberry Pi.

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This is the Zero W, which is slow. Raspberry Pi’s are all slow, but this is the slowest they make. It is still a great little computer. It runs Linux, can use Node.js and even run a full browser like Chrome or Firefox. But this is a computer. It is not a microcontroller.

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This is a microbit. It runs at just 16 MHz and has only 16 KB of RAM. It is slow. But it is not even by far the slowest microcontroller you can find. But it is fast enough to run JavaScript.

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Now comparing it the Raspberry Pi. That is 60 times faster than a Microbit.

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And it has way more memory. So the microbit is on a completely different level.

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Are you crazy? Two years ago when I started playing with microcontrollers I would have said yes. But there are very good reasons why running JavaScript on microcontrollers is brilliant.

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Microcontrollers are very power eﬃcient. I can run JavaScript on a tiny little Bluetooth enabled board and power it using a coin cell battery. And it can run for months. Slow is a good thing, because when we make things faster, they usually require more power.

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And microcontrollers are fast enough. Yes they are slow, but we only have to solve very small problems. Microcontrollers are fast enough for everything I am going to show today.

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And finally they do not need an operating system. At least not in the traditional sense. That may sound bad, but is actually fantastic. Because when I flick the powerswitch, I do not want my Linux powered lamp to take…

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…45 seconds to boot before the lights turn on.

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So let’s take a look at how we can get JavaScript on our microcontrollers. There are lots of different projects, in various stages of maturity and each supporting different types of microcontrollers.

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But we’re going to focus on…. Espruino. Is an open source project. But you can also buy hardware with Espruino already installed. So it is plug and play. There are also has versions that you can flash yourself on your own hardware.

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And it is an interpreter that supports most of JavaScript, even some ES6 features like arrow functions and so. And it even have REPL functionality. So connect to your computer using a USB cable or using Bluetooth and you can execute commands on the microcontroller just like you would in the console of a browser.

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Time for the demo’s. The fun part of this talk. I hope…

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But I do have some warnings to give. This is cutting-edge stuff. Hardware demo’s with experimental technology. And most of it using Bluetooth, a wireless connection…. And Bluetooth uses the same frequency as WiFi, so with a room full of WiFi devices there is lots of opportunity for interference. So this is moment where my heart rate goes through the roof.