embedded operating system leo philip 10/5/2015.. do we need an os ?
TRANSCRIPT
Embedded Operating System
Leo Philip10/5/2015.
Do we need an OS ?
Do we need an OS? ( continued )
Low complex system
Smart Card
Why do we need an OS?
Preemptive kernel
Threads
• A task is known as a thread. The design requires the application to divide the work into tasks. Each task is responsible for a portion of the problem at hand.
• Applications are easier to handle when multithreading is used.
Infinite loop
• Infinite loop is more common due to repetitive work needed in embedded systems.
Scanning a keyboard.
Aircraft Embedded Systems
Avionics Standards are concerned with
1. Level of criticality of software
2. Protection
3. Partition.
General purpose vs. Real time
• Efficient systems can also be built using general purpose operating systems.
States of a Task
• Dormant
• Ready
• Running
• Pending
• Interrupted
Interrupt management
Interrupt controller
Resource Management and Synchronization
• Disable/ enable interrupts
• Semaphores
• Mutex
Memory management
• Dangerous to use malloc() and free() as it leads to fragmentation.
• Solution is to use fixed-size-block partition.
What did we learn?