arduino-uno-rev3

Learn MCU programming from scratch with Arduino Uno Rev3 and Rust. This standalone educational project doesn’t rely on existing crates or dependencies.

Resources

• Arduino UNO Board Docs
• ATmega328p Datasheet
• megaAVR Family Datasheet

MCU Setup and Fuse Configuration

This section provides detailed information on setting up the Microcontroller Unit (MCU) for this board, including specific fuse configurations.

MCU Setup

• Microcontroller: ATmega328P
• Clock Source: External 16MHz crystal
• Bootloader: Arduino IDE provides a convenient way to burn the bootloader onto your microcontroller

Fuse Configuration

Fuses are used to configure various hardware settings of the MCU. Below are the recommended fuse settings for this board:

• Low Fuse: 0xFF
• High Fuse: 0xDE
• Extended Fuse: 0xFD

which corresponds to

• External Crystal Oscillator
• Boot Reset Vector Enabled
• Boot Flash Section Size: 256 words (512 bytes)
• Boot Start Address: 0x3F00
• Serial Program Downloading (SPI) Enabled
• Brown-Out Detection (BOD) Level: 1 (VCC=2.7V)

A new ATmega328P typically does not come with a bootloader, and its default settings may differ. Therefore, a newly purchased chip needs to be set up for the board.

MISC

For more information, refer to the boards.txt file from the Arduino IDE. Here is a summary:

...
uno.bootloader.tool.default=avrdude
uno.bootloader.low_fuses=0xFF
uno.bootloader.high_fuses=0xDE
uno.bootloader.extended_fuses=0xFD
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
uno.bootloader.file=optiboot/optiboot_atmega328.hex
...

Note: If you need to read or write the fuse or lock bit values, you would typically need to use an external hardware programmer (like a USBasp, or another Arduino configured as an “Arduino as ISP”). This is because these operations require a level of access to the microcontroller that the bootloader does not provide.

Reading Lock Bits

avrdude -c arduino -p m328p -P /dev/ttyACM0 -b 115200 -U lock:r:-:h

Reading Fuse Bits

avrdude -c arduino -p m328p -P /dev/ttyACM0 -b 115200 -U lfuse:r:-:h -U hfuse:r:-:h -U efuse:r:-:h

Troubleshooting

Error: no matching serial port found, use -P or set RAVEDUDE_PORT in your environment

Hint: You may want to flash the microcontroller from your host machine (outside devcontainers) to avoid this issue.

Go to the .cargo/config.toml file and add the -P /dev/... flag with the serial port of your Arduino Uno device for the ravedude command. On Linux, it's usually named ttyACM* or ttyUSB*. Run the following command to show new TTY devices:

dmesg | tail | grep -i tty