This course is designed for anyone interested in, or tasked with, the development of a resource constrained Real-Time system. For example, software engineers, field engineers and (project) managers.

• Prior attendance of C Programming for Embedded Systems is recommended or:
• Familiarity with embedded C concepts and programming
• Basic knowledge of embedded processors

An ST STM32F4 (Cortex/M4) with System Workbench IDE

Printed course materials are provided to each delegate.

This course is provided in partnership with embedded experts AC6.

DAY 1 

Cortex-M resources used by RTOS

• Cortex-M Architecture Overview
• Two stacks pointers
• Different Running-modes and Privileged Levels
• MPU Overview
• Systick Timer Description
• Exception / Interrupt Mechanism Overview
• Interrut entry and return Overview
• SVC / PendSV / Systick Interrupt Presentation
• Developing with the IDE

Lab: Interrupt Management on Cortex-M4

Element of a Real-Time system

• Base Real-Time concepts
• The Real-Time constraints
• Multi-Task and Real-Time
• Tasks and Task Descriptors
• Content of the task descriptor
• List of task descriptors
• Context Switch
• Task Scheduling and Preemption
• Tick based or tickless scheduling
• Scheduling systems and schedulability proof
• Fixed priorities scheduling
• RMA and EDF scheduling
• Scheduling through FreeRTOS
• Deterministic preemptive scheduling
• Scheduling strategies
• Cooperative scheduling
• Hybrid scheduling

Lab: Analyse a Context Switch

DAY 2

Task Management

• The Task life-cycle
• Creating tasks
• Deleting tasks
• The Endless-loop pattern

• Task Priorities
• Assigning task priorities
• Changing task priorities
• The idle task
• Idle task hooks
• Timing

Lab: Managing tasks

Resource Management

• Mutual exclusion through FreeRTOS
• Critical sections (interrupt masking)
• Suspending (locking) the scheduler
• Mutexes
• Mutexes concepts
• Mutex or Semaphore
• Recursive or not recursive mutexes
• Priority inversion problem
• Priority inheritance (the automatic answer)
• Priority ceiling (the design centric answer)
• Gatekeeper tasks

Lab: Implement mutual exclusion between tasks

Synchronization Primitives

• Introduction
• Waiting and waking up tasks
• Semaphores
• Events
• Mailboxes
• Binary Semaphores through FreeRTOS
• Give a Binary Semaphore
• Take a binary Semaphore
• Queue Management through FreeRTOS
• Creation
• Sending on a queue
• Receiving from a queue
• Data management
• Sending compound types
• Transferring large data
• Event groups

Lab: Synchronizing a task with another one through binary semaphores 
Lab: Synchronizing a task with another one through queues 

DAY 3

Parallelism Problems Solution

• Parallel programming problems
• Uncontrolled parallel access
• Deadlocks
• Livelocks
• Starvation

Lab: The producer-consumer problem, illustrating (and avoiding) concurrent access problems
Lab: The philosopher’s dinner problem, illustrating (and avoiding) deadlock, livelock and starvation

Interrupt Management

• Need for interrupts in a Real-Time system
• Software Interrupt
• Time Interrupts
• Device Interrupts
• Level or Edge interrupts
• Hardware and Software acknowledge
• Interrupt vectoring
• Interrupts and scheduling
• Deferred interrupt processing through FreeRTOS
• Tasks with interrupt synchronization
• Using semaphores within an ISR
• Counting semaphores
• Using queues within an ISR
• FreeRTOS interrupt processing
• Writing ISRs in C
• Interrupt safe functions
• Interrupt nesting

Lab: Synchronize Interrupts with tasks

Software Timer

• The Timer Daemon Task
• Timer Configuration
• One-shot / Auto-reload Timer
• Software Timer API
• Deferred interrupt handling

Lab: Implement Soft Timers

FreeRTOS-MPU

• The Cortex/M MPU
• User and privileged modes
• Access permissions

• Defining MPU regions
• Overlapping regions
• Predefined regions
• Programmer-defined regions
• Needed linker configuration
• Practical usage tips

Lab: Implement protected memory regions

OPTIONAL ADDITIONAL TOPICS
Data structures

• Need for specific data structures
• Data structures
• Linked lists
• Circular lists
• FIFOs
• Stacks
• Data structures integrity proofs
• Assertions
• Pre and post-conditions
• Thread safety

Lab: Build a general purpose linked list

Memory Management

• Memory management algorithms
• Buddy System
• Best fit / First Fit
• Pools Management
• FreeRTOS-provided memory allocation schemes
• Allocate-only scheme
• Best-fit without coalescing
• Thread-safe default malloc
• Checking remaining free memory
• Adding an application-specific memory allocator
• Memory management errors
• Stack monitoring

Lab: Write a simple, thread safe, buddy system memory manager
Lab: Write a generic, multi-level, memory manager 
Lab: Enhance the memory manager for memory error detection

Trouble Shooting

• Checking for stack problems
• Common pitfalls