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Forced
termination
request
from other
task
SUSPENDED state clear
request from other task
SUSPEND request
from other task
READY state
RUNNING state
WAITING state
WAITING-SUSPENDED
state
DORMANT
state
SUSPENDED
state
WAITING state
clear
t
SUSPEND request
from other task
SUSPENDED state
clear request
MPU execlusive right relinquishment
MPU execlusive right acquisition
Entering the
WAITING state
Task activation
Forced termination
request from other task
WAITING state
l
Figure 3.16 MR100 Task Status Transition
1. RUNNING state
In this state, the task is being executed. Since only one microcomputer is used, it is natural that only one task is
being executed.
The currently executed task changes into a different state when any of the following conditions occurs.
♦ The task has normally terminated itself by ext_tsk service call.
♦ The task has placed itself in the WAITING.
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♦ Since the service call was issued from the RUNNING state task, the WAITING state of another
task with a priority higher than the RUNNING state task is cleared.
♦ Due to interruption or other event occurrence, the interrupt handler has placed a different task
having a higher priority in the READY state.
♦ The priority assigned to the task has been changed by chg_pri or ichg_pri service call so that the
priority of another READY task is rendered higher.
♦ When the ready queue of the issuing task priority is rotated by the rot_rdq or irot_rdq service call
and control of execution is thereby abandoned
When any of the above conditions occurs, rescheduling takes place so that the task having the highest priority
among those in the RUNNING or READY state is placed in the RUNNING state, and the execution of that task
starts.
2. READY state
The READY state refers to the situation in which the task that meets the task execution conditions is still waiting
for execution because a different task having a higher priority is currently being executed.
When any of the following conditions occurs, the READY task that can be executed second according to the
ready queue
is placed in the RUNNING state.
♦ A currently executed task has normally terminated itself by ext_tsk service call.
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By issuing dly_tsk, slp_tsk, tslp_tsk, wai_flg, twai_flg, wai_sem, twai_sem, rcv_mbx, trcv_mbx,snd_dtq,tsnd_dtq,rcv_dtq, trcv_dtq,
vtsnd_dtq, vsnd_dtq,vtrcv_dtq,vrcv_dtq, get_mpf, and tget_mpf service call.