mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 1107

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

The following figure shows the effect of noise early in the start bit time. In this example
C7816[ISO_7816E] = 0. Although this noise does not affect proper synchronization with
the start bit time, it does set the noise flag.
The following figure shows a burst of noise near the beginning of the start bit that resets
the RT clock. In this example C7816[ISO_7816E] = 0. 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.
Freescale Semiconductor, Inc.
RT CLOCK COUNT
RT CLOCK COUNT
RESET RT CLOCK
RESET RT CLOCK
Rx pin input
Rx pin input
RT CLOCK
RT CLOCK
SAMPLES
SAMPLES
Figure 43-97. Start bit search example 3 (C7816[ISO_7816E] = 0)
Figure 43-98. Start bit search example 4 (C7816[ISO_7816E] = 0)
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MCF51JF128 Reference Manual, Rev. 2, 03/2011
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PERCEIVED START BIT
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Chapter 43 Universal Asynchronous Receiver/Transmitter (UART)
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Preliminary
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PERCEIVED AND ACTUAL START BIT
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ACTUAL START BIT
LSB
LSB
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