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MMC2107 - Freescale Semiconductor

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<strong>Freescale</strong> <strong>Semiconductor</strong>, Inc.<br />

Serial Communications Interface Modules (SCI1 and SCI2)<br />

In Figure 16-18, noise is perceived as the beginning of a start bit<br />

although the RT3 sample is high. The RT3 sample sets the noise flag.<br />

Although the perceived bit time is misaligned, the RT8, RT9, and RT10<br />

data samples are within the bit time, and data recovery is successful.<br />

RXD<br />

SAMPLES<br />

PERCEIVED START BIT<br />

ACTUAL START BIT<br />

1 1 1 1 1 0 1 0 0 0 0 0<br />

LSB<br />

nc...<br />

<strong>Freescale</strong> <strong>Semiconductor</strong>, I<br />

RT CLOCK<br />

RT CLOCK COUNT<br />

RESET RT CLOCK<br />

RXD<br />

SAMPLES<br />

RT1<br />

RT1<br />

RT1<br />

RT1<br />

RT1<br />

RT1<br />

RT2<br />

RT3<br />

RT4<br />

RT5<br />

RT6<br />

RT7<br />

RT8<br />

Figure 16-18. Start Bit Search Example 2<br />

RT9<br />

RT10<br />

RT11<br />

In Figure 16-19 a large burst of noise is perceived as the beginning of a<br />

start bit, although the RT5 sample is high. The RT5 sample sets the<br />

noise flag. Although this is a worst-case misalignment of perceived bit<br />

time, the data samples RT8, RT9, and RT10 are within the bit time and<br />

data recovery is successful.<br />

PERCEIVED START BIT<br />

1 1 1 0 0 1 0 0 0 0<br />

RT12<br />

RT13<br />

RT14<br />

ACTUAL START BIT<br />

RT15<br />

RT16<br />

RT1<br />

RT2<br />

RT3<br />

RT4<br />

RT5<br />

RT6<br />

RT7<br />

LSB<br />

RT CLOCK<br />

RT CLOCK COUNT<br />

RT1<br />

RT1<br />

RT1<br />

RT1<br />

RT2<br />

RT3<br />

RT4<br />

RT5<br />

RT6<br />

RT7<br />

RT8<br />

RT9<br />

RT10<br />

RT11<br />

RT12<br />

RT13<br />

RT14<br />

RT15<br />

RT16<br />

RT1<br />

RT2<br />

RT3<br />

RT4<br />

RT5<br />

RT6<br />

RT7<br />

RT8<br />

RT9<br />

RESET RT CLOCK<br />

Figure 16-19. Start Bit Search Example 3<br />

Technical Data <strong>MMC2107</strong> – Rev. 2.0<br />

360 Serial Communications Interface Modules (SCI1 and SCI2) MOTOROLA<br />

For More Information On This Product,<br />

Go to: www.freescale.com

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