MPC5634M Microcontroller Data Sheet, Rev. 9
Overview
Freescale Semiconductor12
• Channel transfers can be suspended by a higher priority channel
2.2.4 Interrupt controller
The INTC (interrupt controller) provides priority-based preemptive scheduling of interrupt requests, suitable for statically
scheduled hard real-time systems. The INTC allows interrupt request servicing from up to 191 peripheral interrupt request
sources, plus 165 sources reserved for compatibility with other family members).
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.
When multiple tasks share a resource, coherent accesses to that resource need to be supported. 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.
Multiple processors can assert interrupt requests to each other through software setable interrupt requests. These same software
setable interrupt requests also can be used to break the work involved in servicing an interrupt request into a high priority portion
and a low priority portion. The high priority portion is initiated by a peripheral interrupt request, but then the ISR asserts a
software setable interrupt request to finish the servicing in a lower priority ISR. Therefore these software setable interrupt
requests can be used instead of the peripheral ISR scheduling a task through the RTOS.
The INTC provides the following features:
• 356 peripheral interrupt request sources
• 8 software setable interrupt request sources
• 9-bit vector addresses
• Unique vector for each interrupt request source
• Hardware connection to processor or read from register
• Each interrupt source can be programmed to one of 16 priorities
• Preemptive prioritized interrupt requests to processor
• ISR at a higher priority preempts executing ISRs or tasks at lower priorities
• Automatic pushing or popping of preempted priority to or from a LIFO
• Ability to modify the ISR or task priority to implement the priority ceiling protocol for accessing shared resources
• Low latency—three clocks from receipt of interrupt request from peripheral to interrupt request to processor
This device also includes a non-maskable interrupt (NMI) pin that bypasses the INTC and multiplexing logic.
2.2.5 FMPLL
The FMPLL allows the user to generate high speed system clocks from a 4 MHz to 20 MHz crystal oscillator or external clock
generator. Further, the FMPLL supports programmable frequency modulation of the system clock. The PLL multiplication
factor, output clock divider ratio are all software configurable. The PLL has the following major features:
• Input clock frequency from 4 MHz to 20 MHz
• Voltage controlled oscillator (VCO) range from 256 MHz to 512 MHz, resulting in system clock frequencies from
16 MHz to 80 MHz with granularity of 4 MHz or better
• Reduced frequency divider (RFD) for reduced frequency operation without forcing the PLL to relock
• 3 modes of operation
— Bypass mode with PLL off
— Bypass mode with PLL running (default mode out of reset)
— PLL normal mode