avr-projects

Bare-metal AVR projects from my second-year college study, rebuilt for the Arduino Uno R3 / ATmega328P.

The important point is that the Arduino Uno is only being used as an ATmega328P development board. The projects do not use Arduino functions such as digitalWrite(), pinMode(), or Serial.begin(). They use AVR registers directly with AVR-GCC, just like normal AVR development.

Project Structure

Each project uses the same simple layout:

Project XX - Project Name/
├── main.c
├── README.md
└── images/
    └── .gitkeep

After rebuilding a circuit, add your own real photo as:

images/breadboard.jpg

Board Mapping

Useful Arduino Uno / ATmega328P mappings:

Arduino pin	AVR pin
D0	PD0 / RXD
D1	PD1 / TXD
D2	PD2 / INT0
D3	PD3 / INT1
D8	PB0
D9	PB1
D10	PB2
D11	PB3 / MOSI
D12	PB4 / MISO
D13	PB5 / SCK / built-in LED
A0	PC0 / ADC0
A1	PC1 / ADC1
A4	PC4 / SDA
A5	PC5 / SCL

Toolchain

Target:

MCU: ATmega328P
Clock: 16 MHz
Compiler: AVR-GCC
Board: Arduino Uno R3

Example compilation:

avr-gcc -mmcu=atmega328p -DF_CPU=16000000UL -Os main.c -o main.elf
avr-objcopy -O ihex -R .eeprom main.elf main.hex

Upload through the Uno bootloader by replacing COM3 with the correct serial port:

avrdude -c arduino -p atmega328p -P COM3 -b 115200 -D -U flash:w:main.hex:i

Projects containing additional .c files must compile those files too. For example, the UART library project can be built with:

avr-gcc -mmcu=atmega328p -DF_CPU=16000000UL -Os main.c uart.c -o main.elf
avr-objcopy -O ihex -R .eeprom main.elf main.hex

Source and Attribution

The project sequence is based on Simply AVR (ببساطة AVR) by Abdallah Ali Abdallah.

The source book is published under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 (CC BY-NC-SA 4.0). No book circuit diagrams or long passages are included here. Project descriptions and code were rewritten for the ATmega328P.

Projects

• Project 01 - Blinking the On-Board LED
• Project 02 - Four Blinking LEDs
• Project 03 - Using PORTB and PORTD as Outputs
• Project 04 - 7-Segment LED Counter
• Project 05 - Digital Input with Pushbutton
• Project 06 - Pushbutton with Internal Pull-Up
• Project 07 - Three Buttons and Three LEDs
• Project 08 - Pushbutton Debouncing
• Project 09 - DC Motor On-Off Control
• Project 10 - DC Motor Direction Control
• Project 11 - External Interrupt INT0
• Project 12 - External Interrupts INT0 and INT1
• Project 13 - UART Transmitter
• Project 14 - UART Receiver
• Project 15 - UART Transmit and Receive
• Project 16 - UART String Transmission
• Project 17 - Reusable UART Driver Library
• Project 18 - ADC Potentiometer Reading
• Project 19 - FreeRTOS - Three LED Tasks