Renesas Electronics America Inc. © 2012 Renesas Electronics America Inc. All rights reserved. Getting Started with Micriμm’s μC/OS-III Kernel © 2012 Renesas Electronics America Inc. All rights reserved.2 Renesas Technology & Solution Portfolio Company Logo HERE © 2012 Renesas Electronics America Inc. All rights reserved.3 Agenda  Introduction  Lab 1  Foreground/Background Systems  Kernel-Based Applications  Initiating Multitasking  Lab 2  Scheduling and Context Switches  Lab 3  Additional Kernel Services  Lab 4  Conclusion 3 © 2012 Renesas Electronics America Inc. All rights reserved.4 Introduction 4 © 2012 Renesas Electronics America Inc. All rights reserved.5 Class Objectives  Understand what services a real-time kernel provides  Learn how to make use of kernel services  Learn how kernels are implemented  Gain experience with an actual kernel 5 © 2012 Renesas Electronics America Inc. All rights reserved.6 Labs  Based on µC/OS-III  Real-time kernel from Micriµm  Concepts underlying the labs are not µC/OS-III-specific  Step-by-step instructions are provided for each lab 6 © 2012 Renesas Electronics America Inc. All rights reserved.7 A µC/OS-III-Based Application 7 Application Code Micriµm’s Modules (Portable Code) Micriµm’s Modules (Hardware-Specific Code) Hardware © 2012 Renesas Electronics America Inc. All rights reserved.8 µC/LIBµC/CPUµC/OS-III A µC/OS-III-Based Application (Cont.) 8 Application Code µC/CPUµC/OS-III BSP Hardware © 2012 Renesas Electronics America Inc. All rights reserved.9 Directory Structure 9 Workspace files © 2012 Renesas Electronics America Inc. All rights reserved.10 e 2 Studio  IDE supporting Renesas MCUs  Based on Eclipse  A variety of debugging features 10 [...]...Lab 1 11 © 2012 Renesas Electronics America Inc All rights reserved 11 Lab 1 Summary  The kernel is built alongside application code  A kernel- based application looks much like any other C program  Application code interacts with the kernel through API functions 12 © 2012 Renesas Electronics America Inc All rights reserved 12 Foreground/Background Systems 13 ©... All rights reserved 14 Foreground/Background Benefits  No upfront cost  Minimal training required  Developers don’t need to learn a kernel s API  No need to set aside memory resources to accommodate a kernel  There is a small amount of overhead associated with a kernel 15 © 2012 Renesas Electronics America Inc All rights reserved 15 Foreground/Background Drawbacks  Difficult to ensure that each... (Cont.)  Problems with multiple developers  Developers’ efforts must be closely coordinated  Difficult expansion, even with one developer  Changes to one portion of the application may negatively impact the remainder of the code 18 © 2012 Renesas Electronics America Inc All rights reserved 18 Kernel- Based Applications 19 © 2012 Renesas Electronics America Inc All rights reserved 19 A Kernel- Based Example... Electronics America Inc All rights reserved 23 Initializing and Starting the Kernel  Application code must initialize the kernel  µC/OS-III is typically initialized in main()  Initialization accomplished through kernel API functions 24 © 2012 Renesas Electronics America Inc All rights reserved 24 OSInit()  Must be invoked before any kernel services are used  Initializes data structures  Creates internal... Application code creates tasks by calling kernel API functions  Each task has its own stack  A priority must be assigned to each task 32 © 2012 Renesas Electronics America Inc All rights reserved 32 Scheduling and Context Switches 33 © 2012 Renesas Electronics America Inc All rights reserved 33 Two Types of Multitasking  Scheduling differs from kernel to kernel  There are two common approaches to... interrupt; Signal USB Task; } void AppTaskUSB (void *p_arg) { while (1) { Wait for signal from ISR; USB_Packet(); } } 20 © 2012 Renesas Electronics America Inc All rights reserved 20 Kernel Basics  Application is divided into tasks  Kernel shares CPU amongst tasks  Developer may assign importance, or priority, to each task 21 © 2012 Renesas Electronics America Inc All rights reserved 21 Template Task static... 2012 Renesas Electronics America Inc All rights reserved 25 µC/OS-III Internal Tasks Always present Optional  Idle Task  Statistics Task  Automatically given lowest priority  Tick Task  Synchronized with a periodic interrupt  Allows µC/OS-III to provide time delays 26 © 2012 Renesas Electronics America Inc All rights reserved  Monitors resource usage  ISR Handler Task  Facilitates deferred interrupt... 35 © 2012 Renesas Electronics America Inc All rights reserved 35 Preemptive Scheduling Interrupt signals the availability of the highpriority task’s data ISR The high-priority task is scheduled by the kernel High-Priority Task Low-Priority Task Time 36 © 2012 Renesas Electronics America Inc All rights reserved 36 . America Inc. © 2012 Renesas Electronics America Inc. All rights reserved. Getting Started with Micriμm’s μC/ OS-III Kernel © 2012 Renesas Electronics America Inc. All rights reserved.2 Renesas. Understand what services a real-time kernel provides  Learn how to make use of kernel services  Learn how kernels are implemented  Gain experience with an actual kernel 5 © 2012 Renesas Electronics. reserved.12 Lab 1 Summary  The kernel is built alongside application code  A kernel- based application looks much like any other C program  Application code interacts with the kernel through API functions 12 ©