mc33596 Freescale Semiconductor, Inc, mc33596 Datasheet - Page 18

• Manufacturer Part Number: mc33596
• Description: Pll Tuned Uhf Receiver For Data Transfer Applications
• Manufacturer: Freescale Semiconductor, Inc

Communication Protocol
10.4 Standby: LVD Mode
The SPI is deselected. Nothing is sent and all incoming data are ignored until CONFB and SEB go low to
switch back to configuration mode.
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11.1 Manchester Coding Description
The MC33596 data manager is able to decode Manchester coded messages. For other codings, the data
manager should be disabled (DME=0) for RAW data to be available on MOSI.
Manchester coding is defined as follows: data is sent during the first half-bit; and the complement of the
data is sent during the second half-bit.
The signal average value is constant. This allows clock recovery from the data stream itself. To achieve
correct clock recovery, Manchester coded data must have a duty cycle between 47% and 53%.
11.2 Preamble, Identifier, Header, and Message
The following description applies if the data manager is enabled (DME = 1).
A complete telegram includes the following sequences: a preamble, an identifier (ID), the preamble again,
a header, the message, and an end-of-message (EOM). These bit sequences are described below.
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If strobe pin is 0 the state is OFF.
If strobe pin is released from 0 while state is OFF, the initial OFF period is completed.
Whenever is the change of duration of one state due to STROBE pin level or a message being
received, this has no influence on the timing of the following states (A, B, or OFF).
Preamble: A preamble is required before the ID and before the header. It enables:
— In the case of OOK modulation, the AGC to settle, and the data slicer reference voltage to
— In the case of FSK modulation, the data slicer reference voltage to settle
— Clock recovery
The preamble content must be defined carefully, to ensure that it will not be decoded as the ID or
the header.
Communication Protocol
settle if DSREF = 1
Figure 8
defines the preamble in OOK and FSK modulation.
0
Figure 7. Example of Manchester Coding
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MC33596 Data Sheet, Rev. 3
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0
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ORIGINAL
DATA
MANCHESTER
CODED DATA
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