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System Integration Unit (SIU)
MPC5644A Microcontroller Reference Manual, Rev. 6
554
Freescale Semiconductor
The digital filter length field in the IRQ digital filter register (SIU_IDFR) specifies the minimum number
of system clocks that the IRQ signal must hold a logic value to qualify the edge-triggered event as a valid
state change. When the number of system clocks in the IRQ counter equals the value in the digital filter
length field, the IRQ state latches and the IRQ counter is cleared.
If the previous filtered state of the IRQ does not match the current state, and the rising- or falling-edge
event is enabled, the IRQ flag bit is set to 1. For example, the IRQ flag bit is set if a rising-edge event
occurs under the following conditions:
•
Previous filtered IRQ state was a logic 0
•
Current latched IRQ state is a logic 1
•
Rising-edge event is enabled for the IRQ
When the counter for an IRQ is not enabled, the state of the IRQ is held in the current and previous state
latches. The IRQ counter operates independently of the IRQ or overrun flag bit. Clearing the IRQ flag or
overrun flag bits does not clear or reload the counter.
Refer to the following sections for more information:
•
Section 16.6.6, External Interrupt Status Register (SIU_EISR)
•
Section 16.6.11, IRQ Rising-Edge Event Enable Register (SIU_IREER)
•
Section 16.6.12, External IRQ Falling-Edge Event Enable Register (SIU_IFEER)
•
Section 16.6.13, External IRQ Digital Filter Register (SIU_IDFR)
16.7.3.1
External interrupts
The IRQ signals map to 15 independent interrupt requests output from the SIU. The IRQ flag bit is set
when a rising-edge and/or falling-edge event occurs for the IRQ. An external IRQ signal is asserted when
all of the following occur:
•
Enable bit is set in the IRQ rising- and/or falling-edge event registers (SIU_IREER, SIU_IFEER)
•
IRQ flag bit is set in the external interrupt status register (SIU_EISR)
•
Enable bit is cleared in the DMA/Interrupt request enable register (SIU_DIRER)
•
Select bit is cleared in the DMA/Interrupt select register (SIU_DIRSR)
The NMI and SWT Interrupts can each generate an NMI Exception or Critical Interrupt Exception as an
input to the core. This selection is controlled by the NMI_SEL8 and NMI_SEL0 (SIU_DIRER) signals
respectively. When WKPCFG_NMI_GPIO213 is enabled as NMI, the pin will override the PCR
configuration after reset. The SIU_DIRER selects between critical and non-maskable interrupt use, the
SIU_EISR reports the status of NMI, and the SIU_IFEER selects edge sensitivity of the NMI input.
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...