1. VDK Concepts and Features How to Create a Project with VDK support
VDK Module Outline
What is the VDK?
Why Do We Need a Kernel?
VDK Concepts and Features
How to Create a Project with VDK support
Debug Capabilities
Summary/Conclusion

2. Included with VisualDSP++ development tools
What is the VDK?
The Visual DSP Kernel is a pre-emptive kernel designed to run efficiently on Analog Devices family processors
Included with VisualDSP++ development tools
No NRE or royalties associated with VDK

3. A simple application that does only one task may not need a kernel
Why do we need a kernel?
A simple application that does only one task may not need a kernel
i.e.) Blind processing of a super loop
If you have more than one task, an application could be structured in a couple of ways
Respond to an event
Events change execution state
Assign tasks a given priority and execute high priority tasks more often
These approaches get difficult when
You need to preserve the state of a task
Low priority tasks may steal processing time longer than anticipated

4. What does a kernel give you?
Automatic preservation of task/system state
Assign a scheduling method to tasks
Provides synchronization abilities
Frees architect from having to design ‘control code’

5. Application code executes in one of two domains
VDK Domain Concepts
Application code executes in one of two domains
1 Thread Domain
2 Interrupt Domain
Applications and algorithms execute in the thread domain under control of the VDK Kernel
Interrupts execute outside this domain and priority is implemented in hardware
Thread execution is halted while in the interrupt domain
Device drivers are a bridge between the two domains

6. More VDK Concepts Signals Threads
A segment of code and it’s related variables/data
Each thread has its own stack and executes in supervisor mode
Interrupts
Priority based in hardware
Strongly recommend writing in assembly but C/C++ is supported
Signals
Semaphores, Events, Device Flags, and Messages
Used to synchronize activity
Device Drivers
Threads do not communicate with hardware directly
Hide the details of the hardware

7. Thread types defined at project creation
Threads
Thread types defined at project creation
Each thread has a unique ThreadID
Each thread has its own stack
Programmers responsibility not to overflow
The size of heap for stack and thread data can be specified

8. Signals are used to synchronize thread activity
Semaphores
Signals are used to synchronize thread activity
A semaphore is a token that threads can post or acquire
i.e.) relay race – second runner can not run until it has the baton
Semaphores can be periodic
allows given tasks to be scheduled on a fixed interval

9. Events are used to synchronize thread activity to the system
Events and Event Bits
Events are used to synchronize thread activity to the system
Used to convey various system states to threads
Similar to semaphores but can convey several combined system states at once

10. Inter-thread communication
Messages
Inter-thread communication
Transfer information between threads
i.e.) Thread A sends some data for processing to Thread B
Application views single and multi- processor systems the same

11. Execute using hardware priorities
Interrupts
Execute using hardware priorities
Spend as little time as necessary and only do the minimal processing required in ISR
Any registers used by an ISR must be saved and restored
ISRs can be written in assembly, C or C++
C/C++ not recommended but included for flexibility

12. Device drivers bridge the gap between the thread and interrupt domains
How threads communicate with hardware
Provides a black box view to the application
A device driver is a single function with multiple entry points
Initialization
Activation
Open
Close
SyncRead
SyncWrite
IOCtl

13. Creating a Project using VDK
VDK support is added from the project wizard in Visual DSP++
Visual DSP++ creates all the necessary project files and skeleton code

14. The System Node
System Control
Thread Configuration
Blackfin Threads

15. Debug Assistance
Integrated in to Visual DSP++
VDK Status window
State of each object, active thread, resource management, etc
VDK History window
Graphical display of system events
Useful when used with Trigger points

16. Allows for rapid prototype of system
VDK Summary
Provides a comprehensive set of services reducing the need to create your own control code
Allows for rapid prototype of system
Easy to move applications/algorithms across ADI processor families
Well integrated with the IDDE for efficient editing and debug