OSEK_Raspberry_Pi_Zero

This repository implements an OSEK-like, bare-metal operating system for Raspberry Pi Zero (ARM1176JZF-S).

Features include:

• OSEK-like OS implementation with support of most common features.
• Sample application featuring tasks and events interacting to produce blinky at 1/2 Hz on the user LED.
• Bare-metal startup using the RPI's standard kernel.img file on SD card.
• Power and port initialization.
• 1ms timebase derived from the low 32-bit clo register of the BCM's 64-bit timer.
• Implementation in C99 with absolute minimal use of assembly.

A clear and easy-to-understand build system based on GNUmake completes this fun and educational project.

This repository provides keen insight on writing your own bare metal operating system from scratch on a modern microcontroller using entirely free tools and open standards.

Details on the Application

Following low-level chip initialization, the program jumps to the main() subroutine in Appli/main.c. Here the single functional line in main() starts the operatng system via call to OS_StartOS().

An idle task and one single extended task animate the user LED, providing a simple blinky LED show at 1/2 Hz.

Building the Application

Build on *nix* is easy using an installed gcc-arm-none-eabi

cd OSEK_Raspberry_Pi_Zero
./Build.sh

The build results including ELF-file, HEX-mask, MAP-file and the kernel.img file are created in the Output directory.

If gcc-arm-none-eabi is not installed, it can easily be installed with

sudo apt install gcc-arm-none-eabi

Continuous Integration

CI runs on pushes and pull-requests with a simple build and result verification on ubuntu-latest using GutHub Actions.

References

Further information on open standard OSEK can be found in ISO 17356 and in the link below:

• https://en.wikipedia.org/wiki/OSEK