Programming Atmega328p with Avrdude
Arduino IDE it’s an awesome tool and helps a lot of beginners to give the first steps with embedded systems. When you start to have bigger projects you may want to change to another tool, my tool of choice for embedded systems is vim and with that comes using a makefile when I want to compile my projects.
I’m doing this tutorial to explain others how to compile your arduino code without the IDE. This requires you to use a library called AVR Libc from Atmel, it is an C library for Atmel AVR 8-bit RISC microcontrollers. The full documentation can be found here.
Before starting the tutorial we need a set of tools that already come with the arduino IDE. The two major tools are a compiler and a software to upload our binary to the microcontroller.
Installing the tools needed in macos is fairly easy using homebrew. We just need to run the following command:
brew install avrdude avr-gcc avr-objcopy
Our code example is the led blink and it’s like the hello world of embedded systems. Consists on a led that blinks at a given frequency. The difference from the implementation that you may be used to is the fact that will be used the AVR Libc.
The implementation of
blink.c will turn on and off the led 13 from your arduino uno every two seconds.
As I said before my tool of choice is
make. This is a build tool that will execute the compilation and conversion to our binary that late will be uploaded to the microcontroller.
The compilation of this example has three steps, shown here:
- Compile the blink.c from C code to an object
- Convert the object to an ELF file
- Convert the ELF file to a binary HEX file
Of course, as your project gets bigger the Makefile will get more complex. The use of dependencies and compatibility with different microcontrollers will make your code and build steps a new challenge. But meantime we just want to understand how to compile our simple “hello world!”.
To run the
Makefile, you just need to be in the same directory as the
Makefile and run the following command:
Yeah, now we have our binary file to be uploaded to the microcontroller. To accomplish that, Atmel has the
Run the following command and parameters:
avrdude -p m328p -P /dev/tty.usbmodem1411 -c arduino -b 115200 -D -U flash:w:blink.hex:i -v
Now you should see your arduino led 13 switching on and off every 2 seconds.