When I start working on a microcontroller project, there are some basic things that
are nice to haves. Basic things like a serial port for debug messages, a continuously
running timer for getting time difference between two points of time(for things like
timeout; or delays). Then most of the time, you need SPI, or I2C, or some other
Unless you have been using the same platform for some time and have your own personal
stash of code snippets to do this, (and unless you wrote then well enough to be
reusable with other projects, might still need some work to make it work too) you’ll
be doing the same things again and it takes time before you get to do the thing you
wanted to do.
Although C++ is not my prferred language for writing code for microcontrollers, I
write much of AVR code in C++(except ‘modules’ deliberately written in .c/.h files to
make them reusable in other c projects), just to be able to use arduino libraries.
This post is to explain the arduino code/libraries build process in some detail and
adapting it to one’s favourite tools.
Having used a simple makefile based compilation system which replicated the arduino
compilation steps(which I made a long time ago for an internship), I was looking for
something a bit more robust and configurable. Found Inotool
randmonly and this was exactly what I wanted. Usage is simple, create a file ino.ino to
specify configuration(board, serial port, baud etc.).
A sample config file could be like:
board-model = yourcustomboard
board-model = yourcustomboard
serial-port = usb
serial-port = usb in the above is not standard)
Usage is simple, write your code in src/, add any libraries(arduino compatible format
so that the build system can find it), write config in ino.ini, and:
(also) ino clean
The overall stucture is then like:
| |--sketch.ino (arduino style c++/wiring code)
|--ArduinoLib/ (arduino style library)
Ino seems to be unmaintained now, but it works fine with arduino1.0.6(1.5.x and later
ones should work too, but I haven’t tried), which ships with avr-gcc 4.3.2. It was only
missing a way to program devices via a programmer instead of using the serial bootloader.
I sent a pull request which enables use of usb programmers from the config, you can
checkout my version from https://github.com/ntavish/ino/ branch patch-1(unmerged), make
sure to checkout this branch.
In the config example above, there is the name
yourcustomboard, which could have been
one of the board names listed inside the file
To make our own custom board available in this list, first create a ‘profile’ for your own board
in any location. The structure for the files in this is:
(Note: you might need to copy the directory
pins_arduino.h is pretty self-explanatory, it is the utility header defined for all supported
boards by arduino IDE so that you can write have straight numbers in
digitalRead/Write etc. instead of
actual MCU pin port/numbers,
SDA/SCL, and utility macros like
digitalPinToPCICR/digitalPinToPCICRbit/.. etc. Customising this you can map pins to your
A sample custom
boards.txt file for a custom board, set for programming with a usb programmer is:
yourcustomboard.name=Your custom board (ATmega1280) 14.745MHz
In this config all of the bootloader settings can be ignored(the fuse settings are only for documentation too).
protocol is the name of the usb programmer(as listed by
avrdude) you plan to use for this board.
maximum_size might be incorrect in this example, since it subtracts bootloader flash size. The
other important settings are
To create your own board’s
boards.txt, just use the nearest board from yours in
/usr/local/share/arduino/hardware/arduino/boards.txt as a template and modify.
I use my favourite editor and jsut use
ino build/ino upload and the workflow is greatly simplified.
Hope you too find it useful!