async-avr

Required packages

Arch linux

sudo pacman -S avr-gcc avr-libc avrdude python-pip

Ubuntu

sudo apt-get install binutils gcc-avr avr-libc avrdude python3-pip

macOS

brew tap osx-cross/avr
# removal needed before upgrading
brew remove avr-gcc avr-binutils avr-libc
# avr-libc is now included in avr-gcc
brew install avr-gcc avr-binutils
brew install avrdude

Alternatively, on a different OS or if you don't want to install system packages, you may use the binaries included with the Arduino IDE. To do so, first find where Arduino preferences are located:

• Windows Store App: %HOME%\Documents\ArduinoData\
• Windows: %APPDATA%\Arduino15\
• macOS: $HOME/Library/Arduino15/
• Linux: ~/.arduino15/

Now, append packages/arduino/tools/avr-gcc/, find the folder in that directory (e.g. 7.3.0-atmel3.6.1-arduino7 at the time of writing), and then finally add /bin. For example, on Linux, you may have $HOME/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin.

Once you have the above path, add it to your path. For example, on macOS or Linux, run export PATH="$HOME/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin:${PATH}".

Initial installation

async-avr needs nightly rust, as of beginning 2021 a special release even see Rahix/avr-hal#124

create a file called rust-toolchain with the contents:

[toolchain]
channel = "nightly-2021-01-07"
components = ["rust-src"]

this file allows you to run all cargo commands with that nightly release automatically selected.

Compiling and Running

We can compile by running

cargo build --examples --release

Note: If you didn't create rust-toolchain this might work:

cargo +nightly build --examples --release

Then, to upload it to a device, run:

avrdude -v -patmega328p -carduino -P/dev/ttyACM0 -b115200 -D -Uflash:w:target/avr-atmega328p/release/examples/serial.elf:e

Change the upload path (target/avr-atmega328p/release/examples/serial.elf) to meet what you want to upload.

If you only have the Arduino IDE installed

Enable "Show verbose output during: upload" in the Arduino IDE. Observe the build logs for an avrdude command—it should look something like:

/path/to/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino17/bin/avrdude -C/path/to/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino17/etc/avrdude.conf -v -patmega328p -carduino -P/dev/ttyACM0 -b115200 -D -Uflash:w:/tmp/arduino_build_721874/Blink.ino.hex:i

Copy that command, but delete everything after -Uflash:w:. Then, without spaces, add the path to your binary. This will typically be target/avr-atmega328p/release/project_name.elf, or target/avr-atmega328p/release/examples/example_name.elf. Finally, add :e. Your final command will probably look something like:

/path/to/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino17/bin/avrdude -C/path/to/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino17/etc/avrdude.conf -v -patmega328p -carduino -P/dev/ttyACM0 -b115200 -D -Uflash:w:target/avr-atmega328p/release/example/serial.elf:e

What about converting to hex first?

Arduino typically converts the compiled binary to raw hex, and many AVR-Rust projects have [followed that pattern][avr-objcopy]. However, there's generally no need to do that, as avrdude has the ability to upload ELF binaries directly.

[avr-objcopy]: https://github.com/Rahix/avr-hal/blob/bfc5dfe67107a68b4a673e54532354af126cb3ba/mkhex.sh#L32