ATEVK1105 Atmel, ATEVK1105 Datasheet - Page 100

• Manufacturer Part Number: ATEVK1105
• Description: KIT EVAL FOR AT32UC3A0
• Manufacturer: Atmel
• Series: AVR®32r
• Type: MCUr

Specifications of ATEVK1105

• Contents: Evaluation Board, Software and Documentation
• Processor To Be Evaluated: AT32UC3A0512
• Processor Series: AVR
• Data Bus Width: 32 bit
• Interface Type: USART, TWI, USB, SPI, Ethernet
• Operating Supply Voltage: 3.3 V
• Silicon Manufacturer: Atmel
• Core Architecture: AVR
• Core Sub-architecture: AVR UC3
• Silicon Core Number: AT32UC3A0512
• Silicon Family Name: AVR
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT32UC3A0
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

16.3.1
16.3.2
16.3.3
32058J–AVR32–04/11
Non maskable interrupts
CPU response
Clearing an interrupt request
oritize between them. All of the input lines in each group are logically-ORed together to form the
GrpReqN lines, indicating if there is a pending interrupt in the corresponding group.
The Request Masking hardware maps each of the GrpReq lines to a priority level from INT0 to
INT3 by associating each group with the INTLEVEL field in the corresponding IPR register. The
GrpReq inputs are then masked by the I0M, I1M, I2M, I3M and GM mask bits from the CPU sta-
tus register. Any interrupt group that has a pending interrupt of a priority level that is not masked
by the CPU status register, gets its corresponding ValReq line asserted.
The Prioritizer hardware uses the ValReq lines and the INTLEVEL field in the IPRs to select the
pending interrupt of the highest priority. If a NMI interrupt is pending, it automatically gets high-
est priority of any pending interrupt. If several interrupt groups of the highest pending interrupt
level have pending interrupts, the interrupt group with the highest number is selected.
Interrupt level (INTLEVEL) and handler autovector offset (AUTOVECTOR) of the selected inter-
rupt are transmitted to the CPU for interrupt handling and context switching. The CPU doesn't
need to know which interrupt is requesting handling, but only the level and the offset of the han-
dler address. The IRR registers contain the interrupt request lines of the groups and can be read
via PB for checking which interrupts of the group are actually active.
Masking of the interrupt requests is done based on five interrupt mask bits of the CPU status
register, namely interrupt level 3 mask (I3M) to interrupt level 0 mask (I0M), and Global interrupt
mask (GM). An interrupt request is masked if either the Global interrupt mask or the correspond-
ing interrupt level mask bit is set.
A NMI request has priority over all other interrupt requests. NMI has a dedicated exception vec-
tor address defined by the AVR32 architecture, so AUTOVECTOR is undefined when
INTLEVEL indicates that an NMI is pending.
When the CPU receives an interrupt request it checks if any other exceptions are pending. If no
exceptions of higher priority are pending, interrupt handling is initiated. When initiating interrupt
handling, the corresponding interrupt mask bit is set automatically for this and lower levels in sta-
tus register. E.g, if interrupt on level 3 is approved for handling the interrupt mask bits I3M, I2M,
I1M, and I0M are set in status register. If interrupt on level 1 is approved the masking bits I1M,
and I0M are set in status register. The handler offset is calculated from AUTOVECTOR and
EVBA and a change-of-flow to this address is performed.
Setting of the interrupt mask bits prevents the interrupts from the same and lower levels to be
passed trough the interrupt controller. Setting of the same level mask bit prevents also multiple
request of the same interrupt to happen.
It is the responsibility of the handler software to clear the interrupt request that caused the inter-
rupt before returning from the interrupt handler. If the conditions that caused the interrupt are not
cleared, the interrupt request remains active.
Clearing of the interrupt request is done by writing to registers in the corresponding peripheral
module, which then clears the corresponding NMIREQ/IREQ signal.
The recommended way of clearing an interrupt request is a store operation to the controlling
peripheral register, followed by a dummy load operation from the same register. This causes a
AT32UC3A
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