XMAS TREE

This project implements a Christmas tree using an Arduino Uno and LEDs.

PREREQUISITES

Hardware

• x1 Arduino Uno
• x1 breadboard
• x3 red LEDs
• x3 green LEDs
• x1 yellow LEDs
• x7 220 Ohm resistors
• x10 jumper wires male-to-male

Software

• Debian-based Linux distro
• rustc / cargo
• gcc-avr
• avrdude

PREREQUISITES INSTALLATION

rustc and cargo

To download and run rustup, execute the following command:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

rustup allows to install and configure the Rust compiler (rustc) and package manager (cargo).

AVR toolchain and flash programmer

The following commands allow to install the necessary AVR tools:

sudo apt update
sudo apt install gcc-avr
sudo apt install avrdude

AVR is the architecture that the Arduino Uno microcontroller is based on (ATmega328P microcontroller).

PROJECT SETUP

Dependencies

In the project Cargo.toml file:

1. Add the dependency for the panic handler under the [dependencies] section:

   [dependencies]
   panic-halt = "0.2.0"
   

2. Add the dependency for the AVR HAL at the end of the file:

   [dependencies.arduino-hal]
   git = "https://github.com/Rahix/avr-hal"
   rev = "4cbb163"
   features = ["arduino-uno"]
   

3. Change the edition field at the top of the file:

    edition = "2018"
   

At the end run the following command to setup the project

cargo update

Target

1. Create a folder called .cargo in the project root directory
2. Inside the new folder create a file called config.toml
3. Write the following lines in the config.toml file:

   [build]
   target = "avr-atmega328p.json"
   
   [unstable]
   build-std = ["core"]
   

4. Download the avr-atmega328p.json file from https://github.com/Rahix/avr-hal/tree/main/avr-specs inside the project root directory
5. If not already present, at the end of the avr-atmega328p.json file add the field:

   "panic-strategy": "abort"
   

Rust buildchain version

Run the command:

rustup override set nightly-2021-01-07

This will set the rust buildchain to a version which is compatible with the AVR toolchain.

COMPILING & FLASHING

To compile the project run the command

cargo build

for the debug version, or

cargo build --release

for the release (optimized) version.

This will create a xmas-tree.elf file inside the target/avr-atmega328p/debug or target/avr-atmega328p/release folder.

To flash the program to the Arduino:

1. Connect the Arduino to the computer via the USB cable
2. Run the commands:

   cd target/avr-atmega328p/debug
   

   or

   cd target/avr-atmega328p/release
   

   then

   avrdude -p m328p -c arduino -P /dev/ttyACM0 -b 115200 -U flash:w:xmas-tree.elf
   

where /ttyACM0 is usually the device file associated to a connected Arduino.

WIRING

The image below shows the circuit.

Every LED is controlled separately by a specific Arduino digital pin; digital pins number 2 through 8 were chosen.

Every LED is connected to ground through a 220 Ohm resistor. One of the ground rails of the breadboard is connected to one of the Arduino GND pins, while the other rail is wired to the first one.