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SCIOPTA - Real-Time Kernel

User’s Manual Manual Version 4.1 9-1

SCIOPTA - Real-Time Kernel

9 Time Management

9.1 Introduction

Time management is one of the most important tasks of a real-time operating system. There are many functions in

SCIOPTA which depend on time. A process can for example wait a specific time for a message to arrive from an-

other process or process can be suspended for a specific time or timer processes

can be defined which are activated

at specific time intervals.

9.2 System Tick

Time is managed by SCIOPTA by a tick timer which can be selected and configured by the user.

Typical time values between two ticks range between one and then milliseconds. It is important to define the tick

value to s

mall as at every tick the kernel has some system work to perform, such as checking time-out and sched-

uling timer processes.

System tick should only be used for time-out and timing functions higher than one system tick. For very precise

iming tasks it is better to use SCIOPTA interrupt processes connected to a CPU hardware timer.

9.2.1 Configuring the System Tick

The system tick is configured by the sciopta configuration utility (see chapter 16.9.2 “Timer and Interrupt Config-

uration Tab” on page 16-11).

Figure 9-1: Tick Timer Configuration

You can use either an internal specific timer for tick or configure an external timer. If an external timer is used a

tick interrupt process must be specified which will call sc_tick at regular intervals.

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