Zilog EZ80F91AZA Manual de usuario descargar pdf (Pagina 34)

UM007518-1211

Zilog Real-Time Kernel: eZ80

CPU

User Manual

Q: When I post a message to a higher-priority thread from an ISR, the context switch

does not occur immediately. Why is that?

A: RZK follows the priorities below, in descending order, for executing components:

ISRInterrupt ThreadUser Priority Threads

Execution is always transferred to the ISR, because it holds the highest priority. Thus, con-

text switching does not occur even when messages are posted to higher-priority threads

from an ISR that runs from the context of a lower-priority thread. Context switching

occurs only when all of the current pending interrupts are serviced.

Q: What happens when I specify zero wait time in calls such as RZKAcquireSema-

phore

or RZKReceiveFromQueue?

A: When zero wait time is specified in these calls, they become non-blocking calls and

return immediately.

Q: Is RZKCreateSemaphore with zero initial count value supported by RZK?

A: Yes, this feature is supported by RZK.

Q: When an RZK thread is deleted does it also release all of the resources created during

its execution?

A: No. RZK does not release any of the resources created when that thread is deleted. But

you can achieve the same functionality by deleting the unwanted resources in the cleanup

functions, which will be executed during the thread deletion.

Q: Does RZK support the Priority Inheritance protocol?

A: Yes. RZK supports Priority Inheritance protocol. For more information about how to

choose the option, refer to the Zilog Real-Time Kernel Reference Manual (RM0006)

which is available free for download from zilog.com and also located in the following

path:

<ZDSII installed directory>\Program

Files\Zilog\ZDSII_eZ80Acclaim!_A.B.C\ZTP\ZTPX.Y.Z_Lib\RZK\Docs

Q: Does the Priority Inheritance protocol take care of both unbounded and bounded pri-

ority inversion?

A: Yes, it does. RZK supports priority inheritance for both unbounded and bounded pri-

ority inversion.

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Zilog EZ80F91AZA Manual de usuario Pagina 34