mg84fl54 Megawin Technology, mg84fl54 Datasheet - Page 55

• Manufacturer Part Number: mg84fl54
• Description: Full-speed Usb Micro-controller
• Manufacturer: Megawin Technology

0: level-triggered.
IP (Address=B8H, Interrupt Priority Register)
PX3: External interrupt 3 priority bit.
PX2: External interrupt 2 priority bit.
PT2: Timer 2 interrupt priority bit.
PS: Serial Port interrupt priority bit.
PT1: Timer 1 interrupt priority bit.
PX1: External interrupt 1 priority bit.
PT0: Timer 0 interrupt priority bit.
PX0: External interrupt 0 priority bit.
AUXIP (Address=AEH, Auxiliary Interrupt Priority Register)
PUSB: USB interrupt priority bit.
PTWSI: 2-wire-Serial-Interface interrupt priority bit.
PKBI: Keypad interrupt priority bit.
PSPI: SPI interrupt priority bit.
13.5. Interrupt Priority
The bit values in the register IP and AUXIP determine what priority level each interrupt has. The following tables
show the bit values and priority levels associated with each combination.
Table 13-2 Priority Level Determined by IP
Table 13-3 Priority Level Determined by AUXIP
For example, if (IP.3)=(1), then Timer 1 has the priority level equal to 1, which is higher than level 0 with
(IP.3)=(0).
An interrupt will be serviced as long as an interrupt of equal or higher priority is not already being serviced. If an
interrupt of equal or higher level priority is being serviced, it won’t be stopped and the new interrupt will wait until
it is finished. If a lower priority level interrupt is being serviced, it will be stopped and the new interrupt will be
serviced immediately. When the new interrupt is finished, the lower priority level interrupt that was stopped will
be completed. In other words, a priority interrupt can itself be interrupted by a higher priority interrupt, but not by
another equal or lower priority interrupt.
MEGAWIN
PUSB
PX3
AUXIP.x
7
7
IP.x
1
0
1
0
PTWSI
PX2
6
6
Interrupt Priority Level
Level 1 (high priority)
Level 0 (low priority)
Interrupt Priority Level
Level 1 (high priority)
Level 0 (low priority)
PKBI
PT2
5
5
PS
4
4
-
MG84FL54B Data sheet
PT1
3
3
-
PX1
2
2
-
PT0
1
1
-
PSPI
PX0
0
0
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