Zilog EZ80F91AZA - Manual (Page 12)

RZK Overview UM007518-1211
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Zilog Real-Time Kernel: eZ80
®
CPU
User Manual
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Interrupts
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Device driver framework
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Board support package
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Table 1 provides a brief description of the RZK objects.
Table 1. Description of RZK Objects
RZK Objects Description
Thread A thread is the basic object of RZK. RZK enables a particular thread to exe-
cute among all other threads, based on its priority and readiness to execute.
Message Queue Two or more threads can use a message queue to communicate with each
other asynchronously. The length of each message is a variable, provided the
size is within the maximum message size given at the time of creation. Mes-
sage contents are user-defined. By default, messages are added to the end of
queue. An option is provided to insert the message at the head of the queue.
Event Group Event is an optional object of RZK. Events can be grouped and operated upon
logically. An event object allows a single thread to wait on one or more exter-
nal event, using a single event API.
Semaphore Semaphore is an optional object of RZK. Semaphore is the only object, which
requires priority inheritance protocol and is tightly coupled with scheduling
methods. As the semaphore uses a mutual-exclusion mechanism, it is not
directed to a specific thread.
Timer A Timer is an optional object of RZK. Timer objects invoke user-supplied func-
tions that are to be processed at set periodic intervals.
Memory as Partitions/
Regions Memory is an optional object of RZK. However, it is required for dynamic
memory allocation by other objects (for example, message queues). Unused
system memory is organized into two categories:
• Partitions: fixed size memory blocks
• Regions: variable size memory blocks
Interrupts An interrupt is a signal from a device attached to a computer or from a pro-
gram within the computer that causes the main program that operates the
computer (the operating system) to stop and service the interrupt.
Device driver framework The device driver framework is a common set of APIs to access any device
that is present in the global device table.
Board support package The board support package consists of drivers for the EMAC, UART, SPI, RTC
and I
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C peripheral blocks of the eZ80 CPU.