PXD20 Datasheet, PDF (11/130 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Overview
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 settable interrupt requests. These same software
settable 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 settable interrupt request to finish the servicing in a lower priority ISR. Therefore these software settable interrupt
requests can be used instead of the peripheral ISR scheduling a task through the RTOS. The INTC provides the following
features:
• Unique 9-bit vector for each of the possible 128 separate interrupt sources
• Eight software triggerable interrupt sources
• 16 priority levels with fixed hardware arbitration within priority levels for each interrupt source
• Ability to modify the ISR or task priority.
— Modifying the priority can be used to implement the Priority Ceiling Protocol for accessing shared resources.
• External non maskable interrupt directly accessing the main CPU critical interrupt mechanism
• 32 external interrupts
1.4.6 QuadSPI serial flash memory controller
The QuadSPI module enables use of external serial flash memories supporting single, dual and quad modes of operation. It
features the following:
• Maximum serial clock frequency 80 MHz
• Memory mapped read access for AHB crossbar switch masters
• Automatic serial flash read command generation by CPU, eDMA, DCU, or DCU-Lite read access on AHB bus
• Supports single, dual and quad serial flash read commands
• Simultaneous mode:
— Supports concurrent read of two external serial flashes
— The quad data streams from the two flashes can be recombined in the QuadSPI to achieve up to 80 MB/s read
bandwidth with 80 MHz serial flash
• 1664-bit buffer with speculative fetch and buffer flush mechanisms to maximize read bandwidth of serial flash
• DMA support
• All Serial Flash program, erase, read and configuration commands available via IP bus interface.
1.4.7 System Integration Unit Lite (SIUL)
The SIUL controls MCU reset configuration, pad configuration, external interrupt, general purpose I/O (GPIO), internal
peripheral multiplexing, and the system reset operation.
The GPIO features the following:
• Up to four levels of internal pin multiplexing, allowing exceptional flexibility in the allocation of device functions for
each package
• Centralized general purpose input output (GPIO) control
• All GPIO pins can be independently configured to support pull-up, pull down, or no pull
• Reading and writing to GPIO supported both as individual pins and 16-bit wide ports
• All peripheral pins can be alternatively configured as both general purpose input or output pins except ADC channels
which support alternative configuration as general purpose inputs
PXD20 Microcontroller Data Sheet, Rev. 2
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
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