diff --git a/_docs/concepts/rtos/comparison/index.md b/_docs/concepts/rtos/comparison/index.md index 72903c4a..a639495e 100644 --- a/_docs/concepts/rtos/comparison/index.md +++ b/_docs/concepts/rtos/comparison/index.md @@ -3,4 +3,99 @@ title: Comparison of these RTOS permalink: /docs/concepts/rtos/comparison/ --- -Work in progress. \ No newline at end of file +The table below compares RTOS +* NuttX +* FreeRTOS +* Zephyr + +regarding the following features: +* Standardized API to Application level +* Maturity +* Supported Hardware +* Scheduling options +* IO Support (native or vendor-specific module needed) +* Networking stack +* Storage and Display +* Memory Footprint +* Safety Certification +* License +* POSIX level support + +Key questions: +* Evaluation POSIX-compliance of RTOS. +* What is the effort in providing an additional layer for non-POSIX RTOS regarding micro-ROS or ROS 2? +* Support of RTOS for specific HW platforms + +Table: + +| **OS** | [NuttX](http://nuttx.org/) | [FreeRTOS](https://sourceforge.net/projects/freertos/) | [Zephyr](https://www.zephyrproject.org/) | +|--------------------------------------------------------------|---------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------| +| **Feature** | | | | +| **Standardization** | | | | +| POSIX | yes | partial | partial | +| POSIX.1 1 | [yes](http://nuttx.org/) | [wrapper](https://interactive.freertos.org/hc/en-us/community/posts/210029046-POSIX-Wrapper-for-FreeRTOS) | partial | +| POSIX.1b 2 | yes | partial | partial | +| POSIX.1c 3 | yes | yes | partial | +| | | | | +| OSEK/VDX | no | no | no | +| **Maturity** | | | | +| First release | 2007 | 2014 | 2016 | +| Last release | 2019 | 2019 | 2019 | +| Update rate | about 3 months | irregular | 3 months | +| Community | open-source | open-source | Linux Foundation Collaboration Project, (Intel, Linaro (ARM), nordic, NXP, Synopsys) | +| | | | | +| **Supported Hardware** | | | | +| Olimex STM32-E407 (Cortex-M4) | yes | yes | yes, [explicitly](https://docs.zephyrproject.org/latest/reference/kernel/scheduling/index.html) | +| Bosch XDK 5 | not explicitly, but similar 6 | yes | yes, [explicitly](https://github.com/zephyrproject-rtos/zephyr/blob/master/ext/hal/README) | +| MPC57xx | no | no | no | +| **Scheduling** | | | | +| Priority-based | FIFO | yes | yes | +| Round-Robin 4 | yes | yes 6 | [co-operative](https://docs.zephyrproject.org/latest/reference/kernel/scheduling/index.html) | +| Sporadic Server | yes | no | no | +| RBS | no | ? | no | +| Semaphore /Mutex Management | yes (Priority Inheritance) | yes | yes | +| **IO** | | | | +| I2C | yes | vendor-specific | yes | +| SPI | yes | vendor-specific | yes | +| UART | hw-specific | vendor-specific | yes | +| USB | yes | vendor-specific | yes | +| CAN | yes | vendor-specific | yes | +| CAnopen | no | vendor-specific | yes | +| Modbus | yes | vendor-specific | ? | +| **Networking** 7 | | | | +| BLE-Stack | unclear | no | yes | +| 6LoWPAN | yes | no | yes | +| TLS | | yes | yes | +| Thread | | ? | ? | +| Ethernet | yes | no | yes | +| Wifi | yes | no | yes | +| NFC | unclear | no | yes | +| RFID | yes | no | yes | +| **Storage & Display** 7 | | | | +| File System | yes | ? | yes | +| Graphical User Interface | | ? | ? | +| **Memory Footprint** | | | | +| RAM | "small footprint" | 236 B scheduler + 64 B / task | "small footprint" | +| ROM | "small footprint" | 5 - 10 kB | "small footprint" | +| **Safety Certification** | | | | +| Software Development Process DO178B Level A / EUROCAE ED-12B | no | [SafeRTOS: DO178C (Aerspace) by Wittenstein](https://www.highintegritysystems.com/safertos/certification-and-standards/) | no | +| Functional Safety IEC-61508 | no | [SafeRTOS (SIL 3)](https://www.freertos.org/FreeRTOS-Plus/Safety_Critical_Certified/SafeRTOS.shtml) | soon | +| **License** | BSD | MIT and Commercial | Apache 2 | + +1 Processes, signals, fpe, segmentation, bus errors, timers, file and directory ops, pipes, c library, IO Port Interface + +2 Real-time, clocks, semaphores, messages, shared mem, async io, memory locking. + +3 Threads. + +4 Executing every task in round-robin fashion but only for a pre-defined time slice. + +5 ARM Cortex M3 EFM32GG390F1024 Giant Gecko family (Silicon Labs). EFM32G880F120-STK ARM Cortex M3 EFM32GG390F1024 Giant Gecko family (Silicon Labs). + +6 [Note: Time slicing](https://www.freertos.org/Documentation/161204_Mastering_the_FreeRTOS_Real_Time_Kernel-A_Hands-On_Tutorial_Guide.pdf) + +7 Hardware-support for Networking and Storage often depends on the platform and sometimes packages of hardware-vendors are available, which work for a particular operating system. But it is in general difficult to determine the harware-support of a given RTOS. + +Some Related Work: +* [Choosing the right RTOS for IoT platform, Milinkovic et al, INFOTEH-JAHORINA Vol. 14, 2015](http://infoteh.rs.ba/zbornik/2015/radovi/RSS-2/RSS-2-2.pdf): comparison of FreeRTOS, ChibiOS/RT, Erika, RIOT +* [FreeRTOS Architecture](https://www.freertos.org/) \ No newline at end of file diff --git a/_docs/concepts/rtos/index.md b/_docs/concepts/rtos/index.md index 54114255..e69ee629 100644 --- a/_docs/concepts/rtos/index.md +++ b/_docs/concepts/rtos/index.md @@ -3,17 +3,17 @@ title: Why a Real-Time Operating System? permalink: /docs/concepts/rtos/ --- -The use of Real-Time Operating Systems (RTOS) is a general practice in nowadays embedded systems. These embedded devices typically consist of a resource-constrained microcontroller that executes an application where the interaction with external components is performed. In many cases, this application contains a time-critical task where a deadline or deterministic response is required. +The use of Real-Time Operating Systems (RTOS) is a general practice in nowadays embedded systems. These embedded devices typically consist of a resource-constrained microcontroller that executes an application where the interaction with external components is performed. In many cases, this application contains a time-critical task where a time-deadline or deterministic response is required. Bare-metal applications are also used nowadays, but it requires a very low-level programming skills and lacks of hardware abstraction layers that RTOSes offers. On the other hand, RTOSes typically uses hardware abstraction layers (HAL) that eases the use of hardware resources, such us timers and communication buses, making easier the development and allowing the reuse of code. In addition, they offer thread and tasks entities that, together with the use of schedulers, provides the necessary tools to implement determinism in the applications. The scheduling normally consists of different algorithms where the user can choose from. Another feature that RTOSes normally offers is the stack management, helping in the correct memory usage of the MCU, a valuable resource in embedded-systems. ## RTOS in micro-ROS -Due to the benefits explained in the introduction, micro-ROS integrates RTOS in its software stack. The use of such a tool enhances the micro-ROS features and allows reusing all the tools and implementations they provide. As the micro-ROS software stack is modular, the exchange of software entities is expected and desired. Same happens with the RTOS. Even that NuttX is the *default* RTOS for the project, it is expected that several of them could replace it. +Due to the benefits explained in the introduction, micro-ROS integrates RTOS in its software stack. The use of such a tool enhances the micro-ROS features and allows reusing all the tools and implementations they provide. As the micro-ROS software stack is modular, the exchange of software entities is expected and desired. Same happens with the RTOS. Even that NuttX is the *default* RTOS for the project, it can be replaced with Zephyr and FreeRTOS. -As the Operating Systems (OS) that are available for computers, the RTOSes also have different support for standard interfaces. This is established in a family of standards named [POSIX](https://pubs.opengroup.org/onlinepubs/9699919799/). As we aim to port or reuse code of ROS 2 that was natively coded in Linux (a mostly POSIX-compliant OS), the use of RTOSes that complies with these standards is beneficial, as the porting effort of the code is minimal. Same as Linux, NuttX complies at a good degree with POSIX standards, making the porting effort minimal. +As the Operating Systems (OS) that are available for computers, the RTOSes also have different support for standard interfaces. This is established in a family of standards named [POSIX](https://pubs.opengroup.org/onlinepubs/9699919799/). As we aim to port or reuse code of ROS 2 that was natively coded in Linux (a mostly POSIX-compliant OS), the use of RTOSes that complies with these standards is beneficial, as the porting effort of the code is minimal. Same as Linux, NuttX and Zephyr complies at a good degree with POSIX standards, making the porting effort minimal. -Notice that the RTOS call are made by several top layers in the micro-ROS stack. The main one using the RTOS primitives is the middleware. The middleware requires accessing to the transport resources of the RTOS (serial, UDP or 6LOWPAN communications for example), it also requires of the time resources of the RTOS to operate properly. In addition, it is expected that the micro-ROS client library could have access to RTOS resources to have control of mechanisms such as scheduling or power management, so the developer could optimize the application in many domains. +Notice that the RTOS call are made by several top layers in the micro-ROS stack. The main one using the RTOS primitives is the middleware. The middleware requires accessing to the transport resources of the RTOS (serial, UDP or 6LoWPAN communications for example), it also requires of the time resources of the RTOS to operate properly. In addition, it is expected that the micro-ROS client library could have access to RTOS resources to have control of mechanisms such as scheduling or power management, so the developer could optimize the application in many domains. By now, micro-ROS supports three RTOSes, which all come with (basic) POSIX implementations: diff --git a/_docs/overview/index.md b/_docs/overview/index.md index 3ca4cfad..55e841ef 100644 --- a/_docs/overview/index.md +++ b/_docs/overview/index.md @@ -20,7 +20,6 @@ Major repositories in order of the layers are: * Applications: * Kobuki demo: [embedded robot driver](https://github.com/micro-ROS/apps/tree/kobuki_rcl_port/examples/kobuki) and [remote ROS 2 software](https://github.com/micro-ROS/micro-ROS_kobuki_demo) - * [Temperature demo](https://github.com/micro-ROS/micro-ROS_temperature_publisher_demo) * Client library: * Extensions to rcl, i.e. the ROS 2 C API: [rcl_executor](https://github.com/micro-ROS/rcl_executor), ... * Extensions for rclcpp: [system_modes](https://github.com/micro-ROS/system_modes/), [TF improvements](https://github.com/micro-ROS/geometry2), ... @@ -44,4 +43,3 @@ Most repositories can be found in GitHub's micro-ROS organization at [github.com | micro-ROS-Agent | [![](https://img.shields.io/badge/read-the%20docs-blue)](https://github.com/micro-ROS/micro-ROS-Agent/blob/master/README.md) | [![](https://img.shields.io/badge/ROS-crystal-brightgreen)](https://github.com/micro-ROS/micro-ROS-Agent/blob/release-crystal-20190312/README.md) | [![](http://build.ros2.org/buildStatus/icon?job=Cbin_uB64__micro-xrce-dds-agent__ubuntu_bionic_amd64__binary)](https://github.com/micro-ROS/micro-ROS-doc/blob/crystal/Installation/repos/agent_minimum.repos) | [![](https://img.shields.io/github/issues/micro-ROS/micro-ROS-Agent)](https://github.com/micro-ROS/micro-ROS-Agent/issues) | | Micro XRCE-DDS | [![](https://img.shields.io/badge/read-the%20docs-blue)](https://micro-xrce-dds.readthedocs.io/en/latest/) | [![](https://img.shields.io/badge/ROS-crystal-brightgreen)](https://github.com/eProsima/Micro-XRCE-DDS/tree/v1.0.3) [![](https://img.shields.io/badge/ROS-dashing-brightgreen)](https://github.com/eProsima/Micro-XRCE-DDS/tree/v1.1.0) | | [![](https://img.shields.io/github/issues/eProsima/Micro-XRCE-DDS.svg)](https://github.com/eProsima/Micro-XRCE-DDS/issues) | | system_modes | [![](https://img.shields.io/badge/read-the%20docs-blue)](https://github.com/micro-ROS/system_modes/blob/master/README.md) | [![](https://img.shields.io/badge/ROS-crystal-brightgreen)](https://github.com/micro-ROS/system_modes/releases) [![](https://img.shields.io/badge/ROS-dashing-brightgreen)](https://github.com/micro-ROS/system_modes/releases) [![](https://img.shields.io/badge/ROS-eloquent-brightgreen)](https://github.com/micro-ROS/system_modes/releases) | [![Build Status](http://build.ros2.org/job/Ddev__system_modes__ubuntu_bionic_amd64/badge/icon)](http://build.ros2.org/job/Ddev__system_modes__ubuntu_bionic_amd64/) | [![](https://img.shields.io/github/issues/micro-ROS/system_modes.svg)](https://github.com/micro-ROS/system_modes/issues) | - diff --git a/_posts/2019-06-03-micro-ROS_temperature_publisher_demo.md b/_posts/2019-06-03-micro-ROS_temperature_publisher_demo.md index 76853428..438a3614 100644 --- a/_posts/2019-06-03-micro-ROS_temperature_publisher_demo.md +++ b/_posts/2019-06-03-micro-ROS_temperature_publisher_demo.md @@ -15,5 +15,3 @@ The next video shows this demo running. **(This video doesn't work on Chrome)** -You can find all the details and how to reproduce in the next link: -[micro-ROS temperature publisher demo](https://github.com/micro-ROS/micro-ROS_temperature_publisher_demo)