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README
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The libopencm3 project aims to create an open-source firmware library for
various ARM Cortex-M3 microcontrollers.
Currently (at least partly) supported microcontrollers:
- ST STM32F1 series
- ST STM32F2 series
- ST STM32F4 series
- NXP LPC1311/13/42/43
The library is written completely from scratch based on the vendor datasheets,
programming manuals, and application notes. The code is meant to be used
with a GCC toolchain for ARM (arm-elf or arm-none-eabi), flashing of the
code to a microcontroller can be done using the OpenOCD ARM JTAG software.
Status and API
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The libopencm3 project is currently work in progress. Not all subsystems
of the microcontrollers are supported, yet.
IMPORTANT: The API of the library is NOT yet considered stable! Please do
not rely on it, yet! Changes to function names, macro names etc.
can happen at any time without prior notice!
TIP: Include this repository as a GIT submodule in your project. To make sure
your users get the right version of the library to compile your project.
For how that can be done refer to the libopencm3-examples repository.
Prerequisites
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Building requires python, and a python YAML module. (Some code is generated)
For Ubuntu
$ [sudo] apt-get install python-yaml
For Fedora
$ [sudo] yum install PyYAML
For Windows
Download and install:
msys - sourceforge.net/projects/mingw/files/MSYS/Base/msys-core/msys-1.0.11/MSYS-1.0.11.exe
Python - http://www.python.org/ftp/python/2.7/python-2.7.msi (use installer to get the right registry keys for PyYAML)
PyYAML - http://pyyaml.org/download/pyyaml/PyYAML-3.10.win32-py2.7.exe
arm-none-eabi toolchain - for example this one https://launchpad.net/gcc-arm-embedded
Run msys shell and set the path without standard Windows paths, so Windows programs such as 'find' won't interfere:
export PATH="/c//Python27:/c/ARMToolchain/bin:/usr/local/bin:/usr/bin:/bin"
After that you can navigate to the folder where you've extracted libopencm3 and build it.
Building
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$ make
You may want to override the toolchain (e.g., arm-elf or arm-none-eabi):
$ PREFIX=arm-none-eabi make
For a more verbose build you can use
$ make V=1
Fine-tuning the build
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The build may be fine-tuned with a limited number of parameters, by specifying
them as environment variables, for example:
$ VARIABLE=value make
* FP_FLAGS - Control the floating-point ABI
If the Cortex-M core supports a hard float ABI, it will be compiled with
floating-point support by default. In cases where this is not desired, the
behavior can be specified by setting FP_FLAGS. Currently, M4F cores default
to "-mfloat-abi=hard -mfpu=fpv4-sp-d16" and others to no FP flags
Examples:
$ FP_FLAGS="-mfloat-abi=soft" make # No hardfloat
$ FP_FLAGS="-mfloat-abi=hard -mfpu=magic" make # New FPU we don't know of
Example projects
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The libopencm3 community has written and is maintaining a huge collection of
examples, displaying the capabilities and uses of the library. You can find all
of them in the libopencm3-examples repository:
https://github.com/libopencm3/libopencm3-examples
Installation
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$ make install
This will install the library into /usr/local. (permissions permitting)
If you want to install it elsewhere, use the following syntax:
$ make DESTDIR=/opt/libopencm3 install
If you want to attempt to install into your toolchain, use this:
$ make DETECT_TOOLCHAIN=1 install
Note: If you install this into your toolchain, you don't need to pass
any extra -L or -I flags into your projects. However, this also means
you must NOT pass any -L or -I flags that point into the toolchain. This
_will_ confuse the linker. (ie, for summon-arm-toolchain, do NOT pass
-L/home/user/sat/lib) Common symptoms of confusing
the linker are hard faults caused by branches into arm code.
You can use objdump to check for this in your final elf.
Coding style and development guidelines
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See HACKING.
License
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The libopencm3 code is released under the terms of the GNU Lesser General
Public License (LGPL), version 3 or later.
See COPYING.GPL3 and COPYING.LGPL3 for details.
IRC
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* You can reach us in #libopencm3 on the freenode IRC network.
Mailing lists
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* Developer mailing list (for patches and discussions):
https://lists.sourceforge.net/lists/listinfo/libopencm3-devel
* Commits mailing list (receives one mail per 'git push'):
https://lists.sourceforge.net/lists/listinfo/libopencm3-commits
Website
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http://libopencm3.org
http://sourceforge.net/projects/libopencm3/