Freescale Semiconductor PXR4030, Reference Manual

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Device Performance Optimization
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 33-15
2. Software Configuration
Description Registers Details
Compiler optimization N/A Use the features of the compiler to select the optimum
trade off between code size and performance
improvements.
Hardware Single Precision
Floating Point Enable with MSR[SPE] Set compiler switches to specify using hardware single
precision floating point as opposed to software
emulation.
Signal Processing Extensions Enable with MSR[SPE] Take advantage of the SPE-APU to encode time critical
functions using SPE assembly code.
Variable Length Encoding Enabled with TLB_MAS2[VLE] Set compiler switches and configure the MMU to take
advantage of the VLE-APU.
3. Peripherals and General Application Guidelines
• Use the eDMAs rather than the core to move data where possible. Most peripherals can generate eDMA requests to
shift data.
— Use the eDMAs to control movement of commands and results from ADC and to maintain circular buffers in system
memory.
— Create circular buffers so that ADC results can be stored in RAM with no core overhead.
• Shift loading from the CPU to the eTPU2 whenever possible.
— The eTPU2 can provide effective CPU off-loading for time & angle based operations.
— The eTPU2 can trigger the ADC directly with no need for CPU interruption.
• Avoid software polling and allow peripherals to trigger interrupts or request eDMA servicing.
— Use hardware instead of software vectored interrupts to reduce latency.
— Trigger eDMA requests rather than interrupting the CPU to move data/results.
• Configure the external memory interface.
— Enable bursting on the external bus.
— Reduce external bus wait states from default maximum settings.
— Place time critical functions in internal memory.
— Small, but frequently executed routines can be considered as candidates to be locked in cache.