Atmel AT32UC3A3128, Manual

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32072H–AVR32–10/2012
AT32UC3A3
11.5.3 Clocks
The clock for the EIC bus interface (CLK_EIC) is generated by the Power Manager. This clock is
enabled at reset, and can be disabled in the Power Manager.
The filter and synchronous edge/level detector runs on a clock which is stopped in any of the
sleep modes where the system RC oscillator is not running. This clock is referred to as
CLK_SYNC. Refer to the Module Configuration section at the end of this chapter for details.
The Keypad scan function operates on the system RC oscillator clock CLK_RCSYS.
11.5.4 Interrupts
The external interrupt request lines are connected to the interrupt controller. Using the external
interrupts requires the interrupt controller to be programmed first.
Using the Non-Maskable Interrupt does not require the interrupt controller to be programmed.
11.5.5 Debug Operation
The EIC is frozen during debug operation, unless the OCD system keeps peripherals running
during debug operation.
11.6 Functional Description
11.6.1 External Interrupts
The external interrupts are not enabled by default, allowing the proper interrupt vectors to be set
up by the CPU before the interrupts are enabled.
Each external interrupt INTn can be configured to produce an interrupt on rising or falling edge,
or high or low level. External interrupts are configured by the MODE, EDGE, and LEVEL regis-
ters. Each interrupt n has a bit INTn in each of these registers. Writing a zero to the INTn bit in
the MODE register enables edge triggered interrupts, while writing a one to the bit enables level
triggered interrupts.
If INTn is configured as an edge triggered interrupt, writing a zero to the INTn bit in the EDGE
register will cause the interrupt to be triggered on a falling edge on EXTINTn, while writing a one
to the bit will cause the interrupt to be triggered on a rising edge on EXTINTn.
If INTn is configured as a level triggered interrupt, writing a zero to the INTn bit in the LEVEL
register will cause the interrupt to be triggered on a low level on EXTINTn, while writing a one to
the bit will cause the interrupt to be triggered on a high level on EXTINTn.
Each interrupt has a corresponding bit in each of the interrupt control and status registers. Writ-
ing a one to the INTn bit in the Interrupt Enable Register (IER) enables the external interrupt
from pin EXTINTn to propagate from the EIC to the interrupt controller, while writing a one to
INTn bit in the Interrupt Disable Register (IDR) disables this propagation. The Interrupt Mask
Register (IMR) can be read to check which interrupts are enabled. When an interrupt triggers,
the corresponding bit in the Interrupt Status Register (ISR) will be set. This bit remains set until a
one is written to the corresponding bit in the Interrupt Clear Register (ICR) or the interrupt is
disabled.
Writing a one to the INTn bit in the Enable Register (EN) enables the external interrupt on pin
EXTINTn, while writing a one to INTn bit in the Disable Register (DIS) disables the external inter-
rupt. The Control Register (CTRL) can be read to check which interrupts are enabled. If a bit in
the CTRL register is set, but the corresponding bit in IMR is not set, an interrupt will not propa-