Information

In the following figure, the verification samples RT3 and RT5 determine that the first low
detected was noise and not the beginning of a start bit. In this example
C7816[ISO_7816E] = 0. The RT clock is reset and the start bit search begins again. The
noise flag is not set because the noise occurred before the start bit was found.
SAMPLES
Rx pin input
RT CLOCK
RT CLOCK COUNT
RESET RT CLOCK
1 1 1
0
1
0 0 0
START BIT
LSB
RT1 RT1 RT1 RT1 RT2 RT4 RT3 RT5 RT1 RT1 RT2 RT3
RT10
RT1 RT2 RT3
1 1
0 0 0 0
RT11 RT12 RT13 RT14 RT15 RT16
RT4 RT5
RT6 RT7 RT8
RT9
Figure 45-222. Start bit search example 1 (C7816[ISO_7816E] = 0)
In the following figure, verification sample at RT3 is high. In this example
C7816[ISO_7816E] = 0. The RT3 sample sets the noise flag. Although the perceived bit
time is misaligned, the data samples RT8, RT9, and RT10 are within the bit time and data
recovery is successful.
SAMPLES
Rx pin input
RT CLOCK
RT CLOCK COUNT
RESET RT CLOCK
1 1 1
0
1
0 0 0
PERCEIVED START BIT
ACTUAL START BIT
LSB
RT1 RT1 RT1 RT1 RT1 RT2 RT1 RT3 RT4 RT5 RT6 RT7
RT13 RT12 RT11 RT14
RT1 RT2 RT3 RT4 RT5 RT6 RT7
1 1
0 0
RT10
RT8 RT9
RT15 RT16
Figure 45-223. Start bit search example 2 (C7816[ISO_7816E] = 0)
In the following figure, a large burst of noise is perceived as the beginning of a start bit,
although the test sample at RT5 is high. In this example C7816[ISO_7816E] = 0. 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.
Functional description
K10 Sub-Family Reference Manual, Rev. 6, Nov 2011
1308 Freescale Semiconductor, Inc.