SPNA135A Datasheet, PDF (5/15 Pages) Texas Instruments – Compatibility Considerations: TMS570LS20x/10x to TMS570LS31x/21x

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Module-Level Feature Differences
• Improved availability; added ability to restart the PLL whenever a PLL slip is detected
3.8 Multi-buffered Serial Peripheral Interface (MibSPI)
The main enhancements to the MibSPI module of the LS31x/21x as compared to the LS20x/10x are:
• Support for half-duplex mode allows the application to use a TX-only or RX-only SPI communication
• Increased the SPICLK prescaler width from 8 bits to 11 bits allows wider range of SPICLK frequencies
for a given peripheral clock frequency.
• Increased the WDELAY parameter width from 6 bits to 8 bits allows configuration of longer delay
between successive transfers.
3.9 High-End Timer (N2HET)
The high-end timer module on the LS31x/21x microcontrollers has undergone a design update while still
maintaining backwards compatibility to the NHET module design implemented on the LS20x/10x
microcontrollers. The most significant enhancements implemented on the N2HET on the LS31x/21x are:
• Added eight new instructions:
– ADD — Add
– ADC — Add with Carry
– AND — Bitwise AND
– OR — Bitwise OR
– SUB — Subtract
– SBB — Subtract with Borrow
– XOR — Bitwise XOR
– RCNT — Ratio Count
• Added three new condition flags:
– C — Carry flag
– N — Negative flag
– V — Overflow flag
• Added two new general-purpose 32-bit registers: R and S
• Integrated hardware angle generator allows the application to generate angle values based on a
toothed-wheel input
• Enhanced input edge detection scheme allows for input pulse widths smaller than 1 loop-resolution
period
• Added hi-res or loop-res option for the PCNT instruction, which allows the application to choose the
resolution for the measurement
• AND-shared outputs allows the application to output a logical AND'ed output of two adjacent channels,
typically required for sound generation
3.10 Parameter Overlay Module (POM)
The main enhancements to the POM module of the LS31x/21x as compared to the LS20x/10x are:
• Added ability to overlay on to internal RAM
• Added time-out feature to prevent a device hang situation in case of a bus stuck error condition
3.11 Real-Time Interrupt Module (RTI)
The main enhancements to the RTI module are:
• Ability to automatically clear compare interrupt signals, which is useful when RTI compare interrupts
are used to periodically trigger a system event, e.g., ADC conversions
• Added digital windowed watchdog functionality, which allows the application to protect against stray
code execution.
SPNA135A – October 2011
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Compatibility Considerations: TMS570LS20x/10x to TMS570LS31x/21x
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