Generator for initializing the EFM32 port for use with RIOT-OS.

EFM32 is a 32-bit micro controller (MCU) family manufactured by Silicon Labs. These MCUs are very energy efficient. RIOT-OS is an operating system for Internet of Things applications. It offers a real-time kernel, peripheral abstraction, drivers and network stack.

This generator prepares the required files for using EFM32 with RIOT-OS, which includes:

• Copying and patching vendor peripheral library (emlib).
• Initializing MCU targets.
• Initializing board targets.

You will need Python 2.7 and the EFM32 SDK (comes with Simplicity Studio).

• The efm2riot/configuration.py defines all the jobs and boards.
• The efm2riot/templates/ folder contains all the files that need to be pre-processed.
• The efm2riot/static/ folder contains files that will be copied.

To generate all files, run:

python EFM2Riot.py --sdk /path/to/sdk --dist dist/

See CONTRIBUTING.md for more information on developing.

When you have cloned this repository, a ready to use version is available in the dist/ folder.

All of the 32-bit families that are supported by emlib are converted:

• EFM32 Gecko
• EFM32 Giant Gecko
• EFM32 Happy Gecko
• EFM32 Jade Gecko
• EFM32 Leopard Gecko
• EFM32 Pearl Gecko
• EFM32 Tiny Gecko
• EFM32 Wonder Gecko
• EFM32 Zero Gecko
• EFR32 Mighty Gecko
• EFR32 Blue Gecko
• EFR32 Flex Gecko
• EZR32 Leopard Gecko
• EZR32 Wonder Gecko

Note: not all MCUs may be supported or have sufficient resources for use with RIOT-OS, for instance, low-memory MCUs.

Currently, the following boards (development kits) are supported:

• STK3200 — EFM32 Zero Gecko
• SLSTK3401A — EFM32 Pearl Gecko
• STK3600 — EFM32 Leopard Gecko
• STK3700 — EFM32 Giant Gecko
• STK3800 — EFM32 Wonder Gecko
• SLWSTK6220A — EZR32 Wonder Gecko (untested)

• General: find out which MCUs are limited to run RIOT-OS.
• General: add support for DMA in peripheral drivers.
• Timer: add LEUART peripherals.

It started as an experiment on generating code from configuration, but turned out to be pretty neat. Apart from that, there are two other reasons:

• This port uses a slightly modified version of emlib. When this library is updated, these changes have to be applied again. This generator automates that process.
• All supported MCUs are extracted from emlib. Using templates, new MCUs that are supported by emlib will also be supported by this port.

The generator is something completely different and has no intention to be part of the RIOT-OS project.

The generated files (the ones in the dist/ folder) could be part of RIOT-OS. However, the developers have a strong preference for a port that is not dependent on any vendor libraries. While I respect this choice, I have the following arguments for using emlib:

• emlib contains powerful assertions to help development.
• (New) families are supported, as long as the emlib API stays the same.
• Chip errata (where possible) ensures consistency across revisions of the same chip. This is applied during chip setup.
• When developing board-specific applications, chances are you will use emlib for accessing peripherals.
• It reduces the number of errors and cuts the development time.
• The library developers have good understanding of the hardware.

There are doubts on the performance and memory overhead of emlib. I have concluded the following, based on a benchmarking script (included):

• Code size does increase when using emlib. The overhead is in the range of 3 to 5 kb of flash, depending on the target and peripherals used.
• A large part of the overhead is contained within the clock management unit. This is an integral part for proper clock setup and low-power support. It is used by all peripherals and has a constant code size.
• Most get/set/read/write/enable/clear methods are implemented as macro's or inline methods. They are equally efficient as their direct register alternative.

Some benchmarks are available at http://basilfx.github.io/EFM2Riot.

See the LICENSE file.

The dist/ folder contains a modified copy of emlib, copyrighted by Silicon Labs. Some of the other port files have been copied from other RIOT-OS ports.