www.ti.com
8.3.5 Enabling and Disabling Interrupts
EABASE
VECTORn
EABASE
VECTORn
CLK
INTn
EINTn
IRQn/FIQn
IRQz/FIQz
ENTRY
Event pulse
Enabled
Disabled
Cleared
EABASE
VECTORn
EABASE
CLK
INTn
EINTn
IRQn/FIQn
IRQz/FIQz
ENTRY
Event pulse
Disabled
Cleared
INTC Methodology
The AINTC has two methods for enabling and disabling interrupts: immediate or delayed, based on the
setting of the IDMODE bit in the INTCTL register. When 0 (default), clearing an interrupt's EINT bit has an
immediate effect. The prioritizer removes the disabled interrupt from consideration and adjusts the
IRQ/FIQENTRY value correspondingly. If no other interrupts are pending, then the IRQz/FIQz output to
the ARM may also go inactive. Enabling the interrupt if it is already pending takes immediate affect. This is
shown in
Figure 8-3. Immediate Interrupt Disable / Enable
If IDMODE is 1, then the EINT effect is delayed. Essentially, the active interrupt status is latched until
cleared by the ARM. If EINT is cleared, the prioritizer continues to use the interrupt and the IRQz/FIQz
remains active. Once the ARM clears the pending interrupt, further interrupts are disabled. In the same
way, setting EINT does not cause the previously pending interrupt event to become enabled until it has
been cleared first. The disable operation is shown in
Figure 8-4. Delayed Interrupt Disable
Interrupt Controller
92
SPRUFB3 – September 2007