Ultra Start 16xx Manual de usuario descargar pdf (Pagina 19)

MEB/0404

ADC

DMA

Fully Automatic

DAC

MSP430F169

DMA Increases Performance 25x

100

“MCU”

100%

kHz

“MCU”

SPI

DAC

ADC

SPI

MIPS

The MSP430F16x is the first MCU family - complete “Signal Chain on Chip” one chip.

•The example shows an application that outputs a sine wave in response to a measured analog

input. The sine wave has 32-steps. We will see that without SCoC, a typical MCU becomes

overloaded and the system performance is very limited.

•The advantage of Signal-Chain-on-Chip is that the MCU does not have to spend resources

handling data and managing serial interfaces between external data converters – instead the

solution is all on one chip – and fully automatic! The DMA can automatically transfer data from

the integrated data converters using only 2 bus clocks. This means with an 8MHz bus clock and

a 32-step sine wave, that a 120kHz output is possible!

•Without DMA the typical software solution quickly becomes overloaded primarily managing the

serial transfers between the external ADC and DAC. The DAC load ISR function alone required

CPU 53 cycles which means at 32-steps, 1696 CPU bus cycles are required for each full sine

wave. With a typical solution the sine wave output is limited to under 5kHz, and the CPU is fully

loaded.

•With SCoC the performance of a system is dramatically increased and CPU resources are

available for more advanced signal processing. This means that MSP430 applications can

operate at lower clock speeds - reducing power consumption and EMI – and deliver higher

performance.

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Ultra Start 16xx Manual de usuario Pagina 19