C Microkernel Realtime eXecutive

This is realtime, microkernel operating system with fully static operation currently targeted towards Cortex-M microcontrollers having usable support for MPU. Currently microcontrollers based on Cortex-M0+, Cortex-M3, Cortex-M4 and Cortex-M7 are known to be supported.

Quickstart

Add CMRX as a submodule of your repository:

git submodule add https://github.com/ventZl/CMRX

Assuming that the SDK for your microcontroller is based on CMSIS standard, you can use the following snippet in your top-level CMakeLists.txt to create firmware skeleton with one process:

list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmrx/cmake)

# Set variables for FindCMSIS to detect and configure the CMSIS
set(CMSIS_ROOT path/to/cmsis/root/in/your/sdk)
set(DEVICE your_device_name)
set(CMSIS_LINKER_FILE path/to/your/linker/file)

include(FindCMSIS)

# Set variables for CMRX to select the right architecture and HAL
set(CMRX_ARCH arm)
set(CMRX_HAL cmsis)
# To get access to special commands
include(CMRX)

# To compile CMRX source
add_subdirectory(cmrx)

# Create firmware, main.c has to host void main(void) function
set(helloworld_SRCS main.c)
add_firmware(helloworld ${helloworld_SRCS})

# Create one process
set(init_SRCS init.c)
add_application(init ${init_SRCS})
target_link_libraries(init stdlib your_hal_lib)

# Link everything together
target_link_libraries(helloworld cmrx aux_systick your_hal_lib)
target_add_application(helloworld init)

Depending on your HAL you might need to change this or add more declarations.

Documentation

There is documentation available online. You can generate documentation using Doxygen directly from the source tree by running:

doxygen

in the root directory of this repository. HTML documentation will be generated into doc/html subdirectory.

Examples

There are some examples of how to use CMRX with various HALs on various platforms in Examples repository.

Features

• microkernel fully isolated from the userspace
• individual userspace processes fully isolated from each other
• device drivers running in userspace with restricted access to peripheral memory area
• priority-aware preemptive scheduler
• basic POSIX-like API for managing threads, timers and signals
• object-oriented remote procedure calling mechanism