Requirements and Environment setup

Hardware requirements

• I have used ATMEGA328P micro-controller here. (Arduino Uno hardware board)

Software requirements

avr-gcc

• You can go to https://www.microchip.com/en-us/tools-resources/develop/microchip-studio/gcc-compilers and download (unzip) the 8-bit AVR toolchain.

• Make sure to add the bin folder in the unzipped toolchain folder in the path. This can be achieved in Ubuntu 22 Linux as shown:
  • Copy the path of the bin folder.
  • Open terminal and make sure you’re in the root directory (which is ~).
  • Now type nano .bashrc to open up the global bash path variable settings file.
  • Add in the path entry for avr toolchain in the end of file.

    export PATH=$PATH:<path to your toolchain>
    # In my case it was,
    # export PATH=$PATH:~/avr8-gnu-toolchain-linux_x86_64/bin

  • Save the file and exit. Now run source .bashrcto reload the path settings.
  • Type in avr-gcc --version in the terminal and now you should see the version details.

    

• avr-objcopy would be present in the toolchain, so we now don’t need to worry about its installation.

avrdude

• This is an open-source programmer for AVR based micro-controllers.

• Can be installed from package manager using the line

  sudo apt-get install avrdude

• Typing in avrdude --version should give you the version results implying that the install was right!

make

• make is used as the build automation tool for generation of object, elf and hex files.

• avrdude is also mentioned in the Makefile to flash the chips (needs fix, currently works only for arduino based programmer and /dev/ttyACM0 port of USB.

Now, you can get started with the Bare-metal programming for AVR Microcontrollers!

Project directory tree

.
├── build
│   ├── main.elf
│   ├── main.hex
│   ├── main.o
│   └── obj
│       ├── delay.o
│       ├── lcd16x2.o
│       └── memorymap.o
├── examples
│   └── blinky.c
├── inc
│   ├── atmega328p
│   │   ├── delay.c
│   │   ├── delay.h
│   │   ├── memorymap.c
│   │   └── memorymap.h
│   └── lib
│       └── lcd16x2
│           ├── lcd16x2.c
│           └── lcd16x2.h
├── Makefile
└── src
    └── main.c

• The user code goes in main.c.

• The micro-controller’s memory map and other relevant files, user defined functions for libraries (under /inc/lib) and header files for the microcontroller such as memory map file go under ./inc/<mcu_name> folder.

• The intermediary object files are compiled to /build/obj/ and the final main.hex file is present in the /build directory.

• Running make commands, will create the necessary elf, hex and .o files.

• The examples directory would contain all the example codes that can be pasted in the main.c file to observe the outputs.