Rust Programming Language Rust Linz, 25 Nov 2022

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From YouTube: Embedded Rust on ESP32 - Juraj Michálek - Rust Linz November 2022

Description

Rust is an excellent language for building embedded systems. Espressif Systems and ESP-RS Open source community made it possible to develop for ESP32 (S2, S3) chips with Xtensa and ESP32-C3 with RISC-V architecture. Developing embedded projects are possible both with STD and Bare Metal. It's very easy to start playing with chips even without hardware, just using the simulator https://wokwi.com/rust . Espressif community also introduced an Open Hardware board with KiCad templates so that anybody can design their own Rust board, a.k.a esp-rs/esp-rust-board.

Juraj on Twitter: https://twitter.com/jurajmichalek
Rust Linz: https://fosstodon.social/@rustlinz - https://twitter.com/rustlinz

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For having me- and we visited also wrestlings in person in September- and it was very nice experience, so we decided uh that we also. We would like to contribute this topic again, but it uh rest on esp32, uh because me, my team and rust Community was working hard to make embedded rest running on esp32s and the family of chips leveled by espressive. So this talk uh won't be just about like embedded rust.

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We will also touch topic like webassembly and how it can be also interesting for embody developers and how you can like reuse, the same business logic that you can write for desktop or server and run the same business Logic on ESP chips. So, let's see um here is the first slide. uh This is kind of like like beginning here. You can see on the pictures. Scott mabin, uh it's the founder of esprs GitHub organization, uh and this is kind of his initial post.

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I I find it funny it's it's like uh Linus turbos when he was uh creating his Linux kernel and he posted the first email. uh This is like a similar post. That Scott did uh that he was trying to get rust running on expressive, uh cheap esp32 by the time and yeah. He had some issues with that, but he finally succeeded in making it happen. You can find more details at his blog neighbors.dev and reads about the history and he's also posting some updates. um Each quarter were removed. What do we added?

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What is possible and also here is a link to YouTube, where you can find Scott's talk about the rust and expressive chips. His uh who is talking more about like generic scope. Today, I will focus more about the Practical details, so I will show you several demonstrations. So, even if you are not like embedded developer, you can see what's possible and you can start thinking.

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How can you reuse the skills that you know from developing for servers or desktop also for embeddy chips, because with rust the barrier is is really getting lower, because previously it was only possible with CEO or Arduino. So, first of all, uh let's start with hardware and thanks to cooperation with rishiket from work we come. We have added a support there with like his great contribution for rust. So now you can play with the embedded Hardware in your web browser without needing to connect any wires and building complex connections like here.

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So let me show you a demo so here it is just type walkway com, slash rust and you should be able to see this page, and here are several examples. You may know this page also with the Arduino examples and micro, Python and circuit python. If you remove the slash rust, you will get a list of other examples. So, let's start, let's select this esp32 no STD example yeah. So so, and now, let's see what what is here on the right side, there is Led with one resistor and esp32 Dev board, which has some gpios.

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If you were watching September talk about Raspberry Pi Lisa was there explaining the situation? If you got the Raspberry Pi, there are also gpios that you can connect to some external hardware situation is your similar instead of Raspberry Pi, we have have your esp32 chip, which is able to communicate with the world using this gpio pins so and let's go to the code. So what we can see here? First of all, uh I'm showing you so-called bare metal rust.

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Why it's important?

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If you are writing normal, desktop honest application, you are probably using the string formatters like four month macro and so on, but this stuff is relatively expensive. If you go to embedded Hardware each byte, each processor cycle counts so um rest offers this unique opportunity to say: okay, I, don't want anything from standard. Library I am going from scratch, so I'm selecting what I'm composing my system from- and this is what no STD allows us to do, and you can find many libraries are already no STD ready.

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So you can just say no features and it will turn the library into no STD mode, for example, anyhow crate or any other of this crate. So we are in ostd mode and uh you will find here a kind of boilerplate code that is very similar across the examples. If you compare it to Arduino examples. Arduino is quite a simple, but let me explain why.

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So, first of all, let's use some crates. We need to access a hardware and in that case we need some Hardware abstraction layer and it's provided by the correct, esp32 Hall and what we are importing here. Let's, let's see here's the clock, yeah, that's something that we understand. We are working something with the CPU clocks.

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Then we have this pack, it's not a Pac-Man, it's a peripheral access, crate and that's something very important in embedded world and each vendor of embedded devices like the chips should publish this because it allows the developer to interact with the hardware. Basically, it's the description of Registries and this like very, very low level stuff. Since we are providing this Hall, you do not need to uh no much details about it, but this is critical to have and then have.

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We have some RTC real-time clocks IO, so we can interact with input output and we will need some delay. So that's what we are importing uh here. You can see that we are also using our own print Ln. This is specific and very optimized written just just for for the chip.

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So this is what I said in the beginning that if I am using nosd I can say: okay, nothing from STD is coming here: I'm using custom implementation of printerland, which has a similar contract like printerland, but it uses I, don't know less memory and it's, for example, without memory allocation critical in some places, and now we are going into the main- and here is how the code starts so I'm grabbing peripherals. This is the thing you can call once and you will get access to the peripherals that chip can control.

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Then we are getting a system and clock here. I can set the CPU frequency, because most of these chips allows you to choose from different clock frequencies by different clock divider. This is important because the higher frequency, uh the more energy intensive, is the computation. So you will burn more energy. The results will be faster, but if you're operating on battery, it's better to tune down the clock, for example to like 80 megahertz, or something like that, if you need more CPU power, you can boost it to 240 if Chip allows it.

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uh Okay. Now here is a small uh dance with the Watchdogs we DDT it's. Basically, we are saying: okay, hey chip, do not care uh about the watch dogs, please disable them and do not reset our application.

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um If we enable the watches, we will require some additional codes to to make what you look happy uh and uh yeah uh here, I am getting the gpio. I am getting the gpio number four you can see. It's here, connect it and uh it's turned into the output pin. So I can write to this thing.

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Yes, so if I put here something it will turn LED on or off, based on the the level of voltage that is here so, let's set High unwrap I can then print hello world to serial console uh and then again switch the LED. So let's run this thing in the simulator and yeah hello world is running and blinking so simple, so we are able to to do it with rust and uh hello links.

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Let's change it just to see whether I'm, uh whether it's able to compile and meanwhile while it's compiling I, can also explain some other tips that you can see here uh here is, for example, the diagram.json. You can put it to your project and basically, in this diagram Json there is the Json representation of the schematics. Here uh you can also see in the simulator cargo Tomo, so you are free to grab this cargo timeline, create your own project with that.

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Okay, so uh one important thing is with the walkway: it's uh for Community, for sharing a knowledge uh you can grab the URL that you have. It has unique ID and send it to anybody else, and the user will see uh exactly the same project and you can create more a project by this and it's even possible to flash your real Chip from here, and there is a hidden F1 I will try to press it, F1 uh palette, where you can have some special commands, and there is also like flash firmware to the device.

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This is really nice. Okay, we got a compilation ready, hello links, hello, lints, so it's working wonderful! The compilation took a little bit longer because it's uh probably the server the runner was down and it took some time to spin it up. But when people are using it, the response time is then uh faster. So it works. Wonderful, let's move back to the walkway. So what you can see here in the first line, you can see uh examples uh based in STD. So let's compare how uh This Blink example.

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Work looks like if I'm implementing so-called STD, it's like you're running on operating system like Linux, so you can use the STD on the Windows. You can use STD and.

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And here you can, you can see this STD uh and uh basically in case of USB chips, we are using ESP IDF framework, which is written in C and the rest application is running on top of this operating system. So that's another option.

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uh We got this this STD approach and this allowed us to to leverage the functions which are provided from ESP IDF I will speak about it later. So, uh let's see what are the other examples here?

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um Let me pick, for example, this one uh with the metrics, and this is really cool, because uh here you can see the the scrolling text. You can see how the hardware is connected to the chip.

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You can see that there's like not many wires and the thing is moving and the really nice thing is, from the source code perspective that, for example, this Max driver that is here for displaying the content is uh uh what was written uh even before we started with this example, so we were able to reuse the code uh from this crate and call it directly, uh because there is already uh no no STD implementation, so this is very nice.

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So if somebody wrote it for PC or Raspberry Pi, you can grab the same crate and uh run it on esps, and this is really like uh very nice.

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um Okay, so hello links, let's try it. Let's try the small update here uh and um here you can see that it's also possible, for example, to call uh unsafe functions. um If you need to do so.

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um So it's like a classical rust, like you can do on on desktop with the bare metal you just control everything that is going uh into the into the mix.

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So uh here are some other examples you can play with it and let me go back to the slides so.

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You can find all the source code related to Valkyrie at github.com.

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The the things are open source. You can contribute your own examples and URI will be more than happy. If you have some like great ideas, you can put it there. We are thinking about organizing a contest for rust community. In writing. These examples so we'll keep you posted about that and then there is also a link to yours. Talk I recommend to watch it uh even though, for example, you're not working directly with us, but you know Arduino, and you know you would like to know more details.

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uh It's uh expressive, developer conference, 22 and Yuri is talking there about esp32 and walkway in the web browser. He did like very amazing job with that so uh and about the operating system. Integrations uh I already mentioned the bare metal that was the first part. I was showing okay. Now we are going like bare metal and uh we don't want any bloat from operating system, but that comes with a cost, and that means that um all drivers that you need for working with peripherals must be ready, and it's not always the case.

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So uh if we go to uh to github.com express sprs organization and look for ESP Hall, which is implementing the bare metal thing here in issues, you can find one pinned issue which tracks current state of supported peripherals and if you are playing with embodied the hardware, probably this abbreviation like the dma, gpio ice, cream, CEO and I score. S will tell you something and you can see that some of them are implemented and some of them are still missing.

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So if you are into the bare metal- and you would like to help us in the community- we are looking for for contributors who would like to solve support for I, don't know uh tray or ohc1. Regarding the Wi-Fi, we have support. There is ESP uh Wi-Fi project, so you can also use the environmental with Wi-Fi it's kind of big data stage, because yeah it's bare metal. So we have to do everything from scratch.

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So uh let's go back here so then uh the second option which operating system you can use is this ESP IDF, it's full featured like you can. If you find USB chip somewhere, I, don't know in some switch around to you.

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uh Then it's probably using USB IDF, because it's based on the free R tools- and there is a CNC plus implementation, then uh for people who would like to be like not so vendor locked in there is another option to use Zephyr for operating system and Zephyr is uh very nice because it allows you to run the rest application on top of it and, for example, you can host one. uh You can host the rest application on One Core uh and and make it isolated.

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This is really nice and similar for nautics notex is more like Linux sich operating system. You get the notion of Slash Dev and uh um you will get a shell, and this is really nice, so you can also use this operating system, but this is more for, like the kernel developers, if you you need to know something about the kernels to work with this thing, um but definitely there are use cases for that.

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um One important thing is that a specific is publishing, also SVD files, which are then used for generating peripheral access crates to access the hardware so uh and uh I will mention here the the product espressif com. uh Just let me show you a quickly uh what it is: it's a product selector. So if you need a special chip, if special parameters, you can filter it here, you can say: okay, I need 12 gpios.

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Please give me all chips that have 12 gpios and if you need some memory, we always recommend to order chips with some PS4 memory for for hobbyist and for makers that allows you to put their bigger application because some, for example, we are hosting in the web server. It makes sense, and you can do some filtering here here- is all even the legendary 8266.

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Unfortunately, the environmental rust support is is not there, because it's kind of all too cheap and for new designs. We recommend esp32 as the Baseline. If you are going for something which is like a really Computing intensive, the S3 is the choice because it is like bigger and has more performance to it so now to to the development, and we have many options: how to develop for uh expressive chips. First of all, you can use the local development like for I, don't know desktop.

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We have this ESP app install is a tool for Mac Linux Windows, even the Mac M1, you just run the USB up, install it bootstrap whole environment, including the rust up and set up all the tool chain, download the leap, C link for you and many other stuff. So uh that's that's relatively easy.

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If you prefer developing in the local container, there is a nice integration of with Portman, Docker or Lima, so you can use just the Visa code remote and in the remote container you can develop, or we have also the support for cloud development using gitput, IO or code spaces, uh and we did talk about this in one talk uh during developer conference: here's the link again so uh and now, let's, let's uh explore how to uh work with it. uh Let's uh create a project.

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Pull the terminal how to start with cargo new.

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Generate so if I go to um the ESP RS here, you can find several repos. uh There is like USB template. This is for bare metal. This is for working with IDF. So let's go for the bare metal implementation, uh I just copy this command, and now I can run the cargo generate and the just as we know, SP example.

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um It's asking whether I would like to include also the vs code files. If I include it, then the vs code is then automatically able to pick it up and run it in remote container or something like that. And now it's asking about the chip, let's say esp32 and uh let's generate the project. Usb example, and let me plug here some esp32 foreign.

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Build and flush the thing so.

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Yeah esp32 is connected and cargo USB flash always build with a release, uh because debug is quite big and you will increase the The Flash time and we can pass there. Also the monitor option, which will Flash and monitor the thing now I can pick the peripheral and uh yeah. It's fetching everything.

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The compilation is running the same thing because we are and if we are building for desktop uh and and at the end it should uh link everything and uh flash it to esp32 yep and the flashing process is here relatively quickly with the bare metals and it's smaller and the chip started. uh It was powered on and chip is alive, Okay.

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So that's um example how to start- and let's do something more I have here another chip or another board with the same chip, this ESP body it just just a few buttons and LCD screen and let's see some other examples that we have here.

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Q body RS example: cargo ESP, Flash, release, monitor.

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Again and select.

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Rotary quickly- and maybe you should see something once it's rebooted yes and there it is hello, rust, wonderful uh and since we are in Rust, we can leverage uh on the examples feature and in the directory examples. You have other examples, so example, and let's see car okay, you can see it's reusing the build process, the build artifacts and soon we should have a moving car on the screen. Yes, yes, yes, it's rolling! It's trolling, nice, uh okay!

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So then um what we also recommend to people when they would like to start is to look directly at the ESP Hall projects and in this ESP Hall. um Let's see, uh for example, C3 uh USB C3 Hall prefer to C3, which is risk architecture. The architecture that I showed you here is the extensor and the one that is being more and more popular. These days are chips with risk, 5 architecture because of price and the power consumption, which is very important for battery operated Solutions.

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So, let's go and let's try to see which examples are provided here and let's choose hello: RGB example: cargo USB, flash release, example, orange hello, RGB and yeah monitor just to see whether it's running now, yeah I, need to add more features here, smart light, because now we will be blinking with a smart light which is confusing many people. It's not LED.

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Let's see it's a smart light, so it has multiple colors, so it's multiple lights in one and yes, it was flashed and now you can see colorful lead that is changing and this algorithm is implemented in Rust. So let's see how this is done. Example, uh hello, RGB and if I go to main Loop, which is here you can see here, I got the for loop. I have Hue and I iterate over zero to 250 uh 255, and then it's converted to uh data which is then sent uh to the smart light, really simple.

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um Yes, so that was what I was showing, uh then let me show you another example um with the S3 box: this is this nice device and in this case uh I will show you how we started the development of POC uh and then we try to do it with the web assembly.

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So let's say that I have the code here.

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Foreign searching for this line: okay, let's flash this this example and this uh this box has a display and there is also an IMU unit with the accelerometer. So if I, there is a small ghost if I tip it uh and it will go down based on the accelerometer values, so maybe I could resend it all right yeah, so that it's not good mace here here, if I tilt it, uh it should move yeah, it's moving based on the the gravity and value of the accelerometer.

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uh So this is originally uh bare metal uh that we wrote and then we uh find out that this embedded Graphics, uh which is kind of a standard for writing uh in the rust for graphical applications and it's possible to run in the web assembly. So let me show you uh how it's can be done with the web assembly, so using sharing the same code I'm now using npm run server. uh This is scaffolding around it.

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The npm is, then calling the cargo to build the the similar thing, but not for extensor or risk 5 Target, but for web assembly, and if I go to localhost, 80 I can see it here. So the same thing that I was running on the chip, thanks to the rust I am running in the web browser so and now here, I can connect, for example, arrows uh as the sensors for for motion so yep. Now this is nice.

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This is working, and uh here I can show you also the the shirt code that we did and uh in esp32s free box I have the similar version that can run uh this uh on this this box. So this is really nice. A very nice feature of rust uh you can have the business logic in this case is moving maze with the ghost and share it within the project.

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So, for example, the graphical developer can iterate really quickly in web assembly and then um the embeddy developer can take the code and uh and make it ready for. uh You know for the running on real Hardware, so really big advantage of having rust.

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Okay, um so that was the bare metal part. uh There is also STD version uh where you can use the existing Wi-Fi existing Bluetooth existing lvg Library. So if you already know C and then by the development, uh then you probably can use this USB IDF combination and we have to say big. Thank you to become big contributors from communities uh next and even Markov, who did like a really amazing job and help us to make this work with uh espressive chips.

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uh One interesting thing that we introduced is also open: Hardware, not only open software, but open Hardware that you can find and espr is, uh and it's uh it's project.

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Board here it is rest board and you can design your own Hardware based on this project. You can even purchase this board it's available on Moser and and um AliExpress, and you can also design your own, so we recommend it for students.

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uh The kai-cad is open source software that you can use for Designing the hardware and you can just produce at the end the Gerber file and send it to a manufacturer to to manufacture your boards with your designs- and we already seen some very nice designs, and this is really cool, because this design is tested and all the hardware here is supported by rust and we we did it. uh The testing and also this rust board is part of training that first systems did so.

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Those of you who are familiar with embedded world news first systems- and you can you- can find more information at their website, so uh we have regular regarding our community. We have this regular community meeting. You can find us at github.com esprs and at the rest of the discussions. uh We are posting um updates and topics for discussion, uh and here is also the link about the training.

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So if you are beginning we, together with them, we published Open Source book that is explaining the basics of how to use embedded rust and how to start the development okay.

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um So we have also some uh awesome list, It's relatively small, but we welcome any contributions. So if we go to sprs- and here in the repository is the awesome list.

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So feel free, if you know about any project that is interesting or any tool related to a specific Chips, please feel free to submit the pr there.

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And here are also some inspiration for you. What is possible to do with uh expressive chips, for example, if you're into variables there is very nice book about Ultimate Guide to inform variable Technologies you can find there are a lot of Inspirations how esp's and can be used, and you can program it in rust or in Arduino. For example. Here is the the community that's created here in Bernal this clocks and, for example, kids during the summer camp were programming, it really nice and from Bratislava the city nearby.

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There is the grafana labs, so even they created some funny examples how to use esp32 like monitoring sourdough, if you are baking a bread with esp32 and connected it to the graph on a cloud which is open source, so so many things to share with you uh and uh we are located in berno in Chicago public. So if you happen to be around in the Bernal, let us know uh we.

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We are happy to to discuss uh with you some topics and uh hopefully the next year, uh if there will be a meet-up in person, probably in spring or a little bit later. We are planning to to organize a workshop, so maybe we can uh have some session also in person with real Hardware uh in lint.

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So that's all from me and I'm ready to answer answer some questions.