USBB17RX78K4-XXX NEC Electronics, USBB17RX78K4-XXX Datasheet - Page 26

• Manufacturer Part Number: USBB17RX78K4-XXX
• Description: 78K/4 series realtime OS
• Manufacturer: NEC Electronics

Fig. 2-3 shows an example where task A has a lower priority than task B.
<1> Task B has issued system call “wai_flg” and is now in the WAIT state.
<2> Task A is under execution (has the highest priority of the tasks in the READY state).
<3> An interrupt occurs while task A is executed, and processing is passed to the interrupt handler.
<4> System call “iset_flg” is issued in the interrupt handler, and task B is waken up.
<5> System call “ret_int” is issued in the interrupt handler.
<6> Because task B has a priority higher than task A, processing is passed to task B.
Interrupt
Task A (PRI=3)
<2>
<3>
CHAPTER 2
Fig. 2-3 Example of “ret_int”
BASIC FUNCTIONS OF RX78K/IV
<4>
Interrupt handler
<5>
iset_flg
(Wakes up task B)
ret_int
Task B (PRI=2)
<1> wai_flg
<6>
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