Sequence Diagram; Figure 4-2: Sequence Diagram - Disturbed Input Signal - Fujitsu ALL Series Application Note

4.2.1 Sequence Diagram

main () /
Application
InitRLT0()
Return
InitExtInt0()
Return
Switch to EI0 ISR
@ Key Press
Switch back
from ISR
Switch to RLT0 ISR
@ Debounce Timer
Expiration
Switch back
from ISR
Switch to EI0 ISR
because of Key Bounce
during Debounce Time
Switch back
from ISR
© Fujitsu Microelectronics Europe GmbH
EXTERNAL INTERRUPTS
Chapter 4 External Interrupt Examples
Driver
Initialize RLT0
Initialize External
Interrupt channel 0
IRQHandler_EI0()
Clear El0 interrupt flag
and disable EI0 interrupt
Trigger RLT0 and
enable RLT0 interrupt
No action since
EI0 interrupts
disabled, but
interrupt flag
remains set
IRQHandler_RLT0()
Clear RLT0 interrupt flag and
disable RLT0 interrupt
Enable EI0 interrupt
IRQHandler_EI0()
Clear El0 interrupt flag
Valid key press if key is
still pressed (i.e. if
EPSR07_PS0 =1) after
debounce delay
Figure 4-2: Sequence Diagram – Disturbed Input Signal
Hardware
First rising
edge at INT0 –
Key press
Consecutive rising
edges at INT0 –
debounce of key
RLT0 Interrupt
- 11 -
RLT0 is initialized to
issue interrupt after
0.26 seconds
External Interrupt channel
0 is initialized for rising
edge interrupts
Waiting for
External
interrupt
EI0 interrupt flag cleared,
EI0 interrupts disabled
RLT0 (key debounce timer)
started
Debounce
delay
RLT0 interrupt flag cleared,
RLT0 interrupts disabled
EI0 interrupts re-enabled
EI0 interrupt flag cleared
Waiting for
External
interrupt
MCU-AN -300203-E-V17