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Showing posts from 2018

Talking about Monotron at RustFest

So, today I did a talk about Monotron at RustFest Paris. You can find the code on my Github and/or on crates.io:
The top-level crateThe generic embedded VGA Framebuffer Driver, with callbacks for hardware specific bitsThe command-line menu systemThe PS/2 keyboard driver (unfinished)The tm4c123x-hal and tm4c123x chip support cratesThe excellent Cortex-M and Cortex-M-RT crates from japaric. If you want to buy a Tiva-C Launchpad (it's the same as a Stellaris Launchpad) of your very own, try RS Components, or Farnell or Digi-Key. Just add a VGA connector and three resistors. The Github README tells you where to put them but I take no responsibility if you blow something up - double-check your working with an oscilloscope before risking your monitor!


You can find the slides here. There's a quick video of the closing animation here. The video of the talk will be on the RustFest Paris website soon!

If you want to ask a question, catch me on IRC (try #rust-embedded) or as @therealjpst…

I decided to make an 1980's Home Computer in Rust - Part 1

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I've had a few projects over the past few years using the TI Stellaris Launchpad. It's nothing particularly special - just a Cortex-M4 based LM4F120 MCU at up to 80 MHz with 256 KiB of Flash and 32 KiB of SRAM, an RGB LED and an on-board USB programmer - but it's pretty cheap and I've gotten to know it quite well.

The provided StellarisWare software was a 300 MiB installer, so I threw that out and wrote all of the drivers from scratch. I started out in C, and managed to get a simple car dashboard module working, using an LCD TFT with on-board framebuffer and 8-bit 6800/8080 bus interface (despite the chip not having such a bus - I cheated and used GPIO pins instead). My first attempt at Rust programming was the stellaris-launchpad crate. This has a few demos that either blink the LED or roll it through an RGB rainbow using the PWM timers. From this, I then decided to move the chip support package into a separate crate, in case anyone wanted to use the chip on a differe…

Supporting the new Embedded HAL

Recently, @japaric posted a about a new approach to an Embedded HAL in Rust. This is something that's been kicked around on #rust-embedded for a while, but it was great to see it get to a point it could be pushed out to the wider world.

I run the Cambridge Rust Meetup and the post coincided with our next Hack-n-Learn evening. The purpose of these evenings is to work through problems together and I decided it would be fun to try and implement the Embedded HAL on my LM4F120 chip crate, and then fix the Stellaris Launchpad examples to use the new HAL. To engage some of the attendees new to Rust, I thought it would help if I did it live on the big projector and talked through the changes as I made them.

Well, despite a quick 10 minute break for pizza (thanks Cambridge Consultants) I managed to get the changes completed to the UART driver in under two hours. Here's what I had to do.

The old UART driver in the LM4F120 crate used my earlier Embedded Serial HAL. That looked like this:

Embedded Rust in 2018

I recently picked up an embedded project that I hadn't touched for a few months, so I could add some new features. I was disappointed to note that it no longer compiled - nothing in the code had changed, but it only compiles with Nightly Rust and that had recently had a bunch of changes that completely broke my build. This is then a tale about what I'd like to see from Rust in 2018.

I know there's been a lot of interest in WASM and other 'high level' applications, but Rust also lends itself very well to embedded development. I have a demonstration project for the Texas Instruments Stellaris Launchpad (now rebadged the Tiva-C Launchpad). This project comprises approximately three Assembler instructions (to bounce into the hardfault handler), and the rest is Rust - no C required! Exception handlers, setting the stack pointer and initialising the .data and .bss segments can all be done in pure Rust. Thanks to brilliant work by the likes of @japaric, with the Xargo cro…