PXS20RM Datasheet, PDF (51/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Introduction
1.4.12 Interrupt Controller (INTC)
The INTC provides priority-based preemptive scheduling of interrupt requests, suitable for statically
scheduled hard real-time systems.
For high-priority interrupt requests, the time from the assertion of the interrupt request from the peripheral
to when the processor is executing the interrupt service routine (ISR) has been minimized. The INTC
provides a unique vector for each interrupt request source for quick determination of which ISR needs to
be executed. It also provides an ample number of priorities so that lower priority ISRs do not delay the
execution of higher priority ISRs. To allow the appropriate priorities for each source of interrupt request,
the priority of each interrupt request is software configurable.
The INTC supports the priority ceiling protocol for coherent accesses. By providing a modifiable priority
mask, the priority can be raised temporarily so that all tasks which share the resource can not preempt each
other.
The INTC provides the following features:
• Duplicated periphery
• Unique 9-bit vector per interrupt source
• 16 priority levels with fixed hardware arbitration within priority levels for each interrupt source
• Priority elevation for shared resource
The INTC is replicated for each processor.
1.4.13 System Clocks and Clock Generation
The following list summarizes the system clock and clock generation on this device:
• Lock status continuously monitored by lock detect circuitry
• Loss-of-clock (LOC) detection for reference and feedback clocks
• On-chip loop filter (for improved electromagnetic interference performance and fewer external
components required)
• Programmable output clock divider of system clock (1, 2, 4, 8)
• PWM module and as many as three eTimer modules running on an auxiliary clock independent
from system clock (with max frequency 120 MHz)
• On-chip crystal oscillator with automatic level control
• Dedicated internal 16 MHz internal RC oscillator for rapid start-up
— Supports automated frequency trimming by hardware during device startup and by user
application
• Auxiliary clock domain for motor control periphery (PWM, eTimer, CTU, ADC, and SWG)
1.4.14 Frequency-Modulated Phase-Locked Loop (FMPLL)
Each device has two FMPLLs.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
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