NXP Semiconductors freescale K51 Series Reference Manual

SAMPLESRx pin inputRT CLOCKRT CLOCK COUNTRESET RT CLOCK1 1 1 1 0 0START BIT LSBRT1RT1RT1RT1RT1RT1RT1RT1RT1RT1RT2RT3RT1RT1RT1RT1RT1RT1RT1RT1RT1NO START BIT FOUND1 1 1 1 1 1 1 0 0 0 0 0 0 0 0RT4RT5RT6RT7RT1RT1RT1Figure 48-226. Start bit search example 5 (C7816[ISO_7816E] = 0)In the following figure, a noise burst makes the majority of data samples RT8, RT9, andRT10 high. In this example C7816[ISO_7816E] = 0. This sets the noise flag but does notreset the RT clock. In start bits only, the RT8, RT9, and RT10 data samples are ignored.In this example, if C7816[ISO_7816E] = 1 then a start bit would not have been detectedat all since at least two of the three samples (RT8, RT9, RT10) were high.SAMPLESRx pin inputRT CLOCKRT CLOCK COUNTRESET RT CLOCK1 1 1 1 0 0START BIT LSBRT1RT1RT1RT1RT1RT1RT1RT1RT1RT1RT2RT3RT10RT1RT2RT31 1 1 1 1 0 0 1 0 1RT4RT5RT6RT7RT8RT9RT11RT12RT13RT14RT15RT16Figure 48-227. Start bit search example 648.4.2.5 Framing errorsIf the data recovery logic does not detect a logic 1 where the stop bit should be in anincoming frame, it sets the framing error flag, S1[FE] if S2[LBKDE] is disabled. A breakcharacter when S2[LBKDE] is disabled also sets the S1[FE] because a break characterhas no stop bit. The S1[FE] is set at the same time that received data is placed in thereceive data buffer. Framing errors are not supported when C7816[ISO7816E] is set/enabled. However, if the S1[FE] is set data will not be received when C7816[ISO7816E]is set.Functional descriptionK51 Sub-Family Reference Manual, Rev. 6, Nov 20111272 Freescale Semiconductor, Inc.