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Example projects & code for Atmel ATMega8.

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avr-samples

This repository is intended to contain detailed instructions on how to get started with programming Atmel AVR microcontrollers. It also contains a bunch of thoroughly documented and explained example projects.

Running the code

  1. Wire up your circuit correctly on the breadboard.
  2. Connect the MCU to your PC using a USBasp programmer
  3. cd , for example cd blink
  4. make flash

What Makefiles do, explained

Compile .c files

First, you need to compile a C source file to an .elf object file.

avr-gcc -mmcu=atmega8 -Wall -Os -o blink.elf blink.c -DF_CPU=1000000UL

DF_CPU=1000000UL sets F_CPU to 1MHz.

Convert .elf files to .hex files

To flash the MCU using USBasp programmer, you need a .hex file. It can be created out of the .elf file you generated in the previous step.

avr-objcopy -j .text -j .data -O ihex blink.elf blink.hex

Flash

Now it's time to run the code

avrdude -c usbasp -p m8 -e -U flash:w:blink.hex

Setup with VSCode

macOS

First things first: you need Homebrew.

  1. Install avrdude - a small program used to flash AVR microcontrollers brew install avrdude
  2. Install avr-gcc - an AVR-flavor of GNU GCC brew tap osx-cross/avr brew install avr-gcc
  3. Install a C/C++ Extension for VSCode
  4. To make VSCode's IntelliSense detect AVR header files, make the editor aware of them. For this, you'll need to know the exact version of your avr-gcc installation: brew ls avr-gcc

It prints a list which contains:

/usr/local/Cellar/avr-gcc//avr/include/

Copy that line, replacing with your version.

Now, in project root, create a .vscode folder. In it, create settings.json file with the following content:

Example (for avr-gcc v9.3.0 and using headers for ATmega8A)

< "C_Cpp.default.includePath": [" /usr/local/Cellar/avr-gcc@9/9.3.0_2/avr/include/"], "C_Cpp.default.defines": ["__AVR_ATmega8A__"] >

Voilà, IntelliSense should work now.

Windows

  1. Install avr-gcc - an AVR-flavor of GNU GCC. This version (which we recommend ) contains also avrdude , make and a couple other GNU tools, so you won't have to install them separately. Install it to your home directory (e.g C:\Users\Bartek ) so that it'll be easy to find - in our case, it's C:\Users\Bartek\avr-gcc
  2. Add the location where you installed avr-gcc to $PATH (how to add items to path on Windows?)
  3. Install a C/C++ Extension for VSCode
  4. To make VSCode's IntelliSense detect AVR header files, make the editor aware of them. For this, you'll need to know the exact location of your avr-gcc installation. In our case it was C:\Users\Bartek\avr-gcc . To that location, we need append \bin , like this: C:\Users\Bartek\avr-gcc\bin

Example (using headers for ATmega8A)

.vscode/settings.json

< "C_Cpp.default.includePath": ["C:\\Users\\Bartek\\avr-gcc\\avr\\include"], "C_Cpp.default.defines": ["__AVR_ATmega8A__"] >

This is almost enough, but chances are, if you use sei() or ISR functions for interrupts, your IntelliSense will show errors. To fix them, create a new file named c_cpp_properties.json in .vscode directory in this project's root with the following content:

.vscode/c_cpp_properties.json

< "configurations": [ < "name": "Win32", "includePath": ["$"], "cStandard": "c99", "cppStandard": "c++17", "intelliSenseMode": "gcc-x64" > ], "version": 4 >

Voilà, IntelliSense should work just fine.

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