ULP Advisor > Rule 12.1 Use DMA for large memcpy() calls

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ULP Advisor - Rule Table

ULP 1.1 Ensure LPM usage
ULP 2.1 Leverage timer module for delay loops
ULP 3.1 Use ISRs instead of flag polling
ULP 4.1 Terminate unused GPIOs
ULP 5.1 Avoid processing-intensive operations: modulo, divide.
ULP 5.2 Avoid processing-intensive operations: floating point
ULP 5.3 Avoid processing-intensive operations: (s)printf()
ULP 6.1 Avoid multiplication on devices without hardware multiplier
ULP 6.2 Use MATHLIB for complex math operations
ULP 6.3 Use Low Energy Accelerator (LEA) software library
ULP 7.1 Use local instead of global variables where possible
ULP 8.1 Use 'static' & 'const' modifiers for local variables
ULP 9.1 Use pass by reference for large variables
ULP 10.1 Minimize function calls from within ISRs
ULP 11.1 Use lower bits for loop program control flow
ULP 11.2 Use lower bits for port bit-banging
ULP 12.1 Use DMA for large memcpy() calls
ULP 12.1b Use DMA for potentially large memcpy() calls
ULP 12.2 Use DMA for repetitive transfer
ULP 13.1 Count down in loops
ULP 14.1 Use unsigned variables for indexing
ULP 15.1 Use bit-masks instead of bit-fields

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What it means

The DMA peripheral can be configured to automate the data/memory transfer process without CPU intervention, hence reduce the power consumption.

Risks, Severity

Transferring a large amount of data usually requires a long period of time, depending on the transfer speed clock as well as the read/write speed of the source & destination. Keeping the CPU in active mode during this time greatly increases the power consumption of the device.

Why it is happening

The code contains at least one instance of memcpy() call with transfer size greater than 100

Remedy

Configure the DMA peripheral available on the device to perform the data/memory transfer instead using the memcpy() function call.

Code Example

See the rest of the code examples for all MSP430 devices here!

More Resources

For more details on DMA usage, refer to your device family user's guide.

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