DSP56857 datasheet(251/662 Pages) FREESCALE

Il numero della parte	DSP56857

Spiegazioni elettronici	Digitial Signal Controller

PDF	662 Pages

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Produttore elettronici	FREESCALE [Freescale Semiconductor, Inc]

Homepage	http://www.freescale.com

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Functional Description

Serial Communications Interface (SCI), Rev. 4

Freescale Semiconductor

10-15

Figure 10-9. Start Bit Search Example 3

Figure 10-10 illustrates the effect of noise early in the Start bit time. Although this noise does not

affect proper synchronization with the Start bit time, it does set the Noise Flag.

Figure 10-10. Start Bit Search Example 4

Figure 10-11 demonstrates a burst of noise near the beginning of the Start bit that resets the RT

clock. The sample after the reset is low but is not preceded by three high samples that would

qualify as a falling edge. Depending on the timing of the Start bit search and on the data, the

frame may be missed entirely or it may set the framing error flag.

RESET RT CLOCK

SAMPLES

RT CLOCK

RT CLOCK COUNT

ACTUAL START BIT

RXD

LSB

PERCEIVED START BIT

RESET RT CLOCK

SAMPLES

RT CLOCK

RT CLOCK COUNT

PERCEIVED AND ACTUAL START BIT

RXD

LSB

DSP56857 Scheda tecnica(PDF) 251 Page - Freescale Semiconductor, Inc