RTOS

Overview

In Nuclei SDK, we have support three most-used RTOSes in the world, FreeRTOS, UCOSII and RT-Thread from China.

If you want to use RTOS in your application, you can choose one of the supported RTOSes.

Note

When you want to develop RTOS application in Nuclei SDK, please don’t reconfigure SysTimer and SysTimer Software Interrupt, since it is already used by RTOS portable code.

FreeRTOS

FreeRTOS is a market-leading real-time operating system (RTOS) for microcontrollers and small microprocessors.

In our FreeRTOS portable code, we are using SysTimer Interrupt as RTOS SysTick Interrupt, and using SysTimer Software Interrupt to do task switch.

These two interrupts are kept as lowest level, and SysTimer Interrupt is initialized as non-vector interrupt, and SysTimer Software Interrupt is initialized as vector interrupt.

In our FreeRTOS porting, we also allow FreeRTOS configuration variable configMAX_SYSCALL_INTERRUPT_PRIORITY which can be find in https://www.freertos.org/a00110.html.

The configMAX_SYSCALL_INTERRUPT_PRIORITY should be set to be a absolute interrupt level range from 1 to (2^lvlbits-1) while lvlbits = min(nlbits, CLICINTCTLBITS).

If you set configMAX_SYSCALL_INTERRUPT_PRIORITY to value above the accepted value range, it will use the max value.

If you want to learn about how to use FreeRTOS APIs, you need to go to its website to learn the FreeRTOS documentation in its website.

In Nuclei SDK, if you want to use FreeRTOS in your application, you need to add RTOS = FreeRTOS in your application Makefile.

And in your application code, you need to do the following things:

  • Add FreeRTOS configuration file -> FreeRTOSConfig.h

  • Include FreeRTOS header files

Note

  • You can check the application\freertos\demo for reference

  • Current version of FreeRTOS used in Nuclei SDK is V10.3.1

  • If you want to change the OS ticks per seconds, you can change the configTICK_RATE_HZ defined in FreeRTOSConfig.h

More information about FreeRTOS get started, please click https://www.freertos.org/FreeRTOS-quick-start-guide.html

UCOSII

UCOSII a priority-based preemptive real-time kernel for microprocessors, written mostly in the programming language C. It is intended for use in embedded systems.

In our UCOSII portable code, we are using SysTimer Interrupt as RTOS SysTick Interrupt, and using SysTimer Software Interrupt to do task switch.

If you want to learn about UCOSII, please click https://www.micrium.com/books/ucosii/

We are using the opensource version of UC-OS2 source code from https://github.com/SiliconLabs/uC-OS2, with optimized code for Nuclei RISC-V processors.

In Nuclei SDK, if you want to use UCOSII in your application, you need to add RTOS = UCOSII in your application Makefile.

And in your application code, you need to do the following things:

  • Add UCOSII application configuration header file -> app_cfg.h and os_cfg.h

  • Add application hook source file -> app_hooks.c

  • Include UCOSII header files

Note

  • You can check the application\ucosii\demo for reference

  • The UCOS-II application configuration template files can also be found in https://github.com/SiliconLabs/uC-OS2/tree/master/Cfg/Template

  • Current version of UCOSII used in Nuclei SDK is V2.93.00

  • If you want to change the OS ticks per seconds, you can change the OS_TICKS_PER_SEC defined in os_cfg.h

Warning

  • For Nuclei SDK release > v0.2.2, the UCOSII source code is replaced using the version from https://github.com/SiliconLabs/uC-OS2/, and application development for UCOSII is also changed, the app_cfg.h, os_cfg.h and app_hooks.c files are required in application source code.

RT-Thread

RT-Thread RT-Thread was born in 2006, it is an open source, neutral, and community-based real-time operating system (RTOS).

RT-Thread is mainly written in C language, easy to understand and easy to port(can be quickly port to a wide range of mainstream MCUs and module chips).

It applies object-oriented programming methods to real-time system design, making the code elegant, structured, modular, and very tailorable.

In our support for RT-Thread, we get the source code of RT-Thread from a project called RT-Thread Nano, which only provide kernel code of RT-Thread, which is easy to be intergated with Nuclei SDK.

In our RT-Thread portable code, we are using SysTimer Interrupt as RTOS SysTick Interrupt, and using SysTimer Software Interrupt to do task switch.

And also the rt_hw_board_init function is implemented in our portable code.

If you want to learn about RT-Thread, please click:

In Nuclei SDK, if you want to use RT-Thread in your application, you need to add RTOS = RTThread in your application Makefile.

And in your application code, you need to do the following things:

  • Add RT-Thread application configuration header file -> rtconfig.h

  • Include RT-Thread header files

Note

  • In RT-Thread, the main function is created as a RT-Thread thread, so you don’t need to do any OS initialization work, it is done before main