PC312XDP512F0CFVR datasheet(506/1348 Pages) FREESCALE

Part #	PC312XDP512F0CFVR

Description	HCS12X Microcontrollers

PDF	1348 Pages

Scroll/Zoom	100%

Manufacturer	FREESCALE [Freescale Semiconductor, Inc]

Direct Link	http://www.freescale.com

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506 / 1348 page

Chapter 11 Serial Communication Interface (S12SCIV5)

MC9S12XDP512 Data Sheet, Rev. 2.21

506

Freescale Semiconductor

In Figure 11-24, a large burst of noise is perceived as the beginning of a start bit, although the test sample

at RT5 is high. The RT5 sample sets the noise ﬂag. Although this is a worst-case misalignment of perceived

bit time, the data samples RT8, RT9, and RT10 are within the bit time and data recovery is successful.

Figure 11-24. Start Bit Search Example 3

Figure 11-25 shows 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 11-25. Start Bit Search Example 4

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

PC312XDP512F0CFVR Datasheet(PDF) 506 Page - Freescale Semiconductor, Inc