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MC68HC11P2 Datasheet, PDF (113/268 Pages) Motorola, Inc – Microcontrollers | |||
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Freescale Semiconductor, Inc.
Motorola Interconnect Bus (MI BUS)
Biphase coding
6.6 Biphase coding
Manchester biphase L coding is used for the push field bits. Each bit
requires two time slots to encode the logic value of the bit. This encoding
allows the detection of a single error at the time slot level. Bits are
encoded as follows:
1 = In the first time slot, the logic level is set to zero, followed by a
logic level one in the second time slot;
0 = In the first time slot, the logic level is set to one, followed by a
logic level zero in the second time slot.
â0â
â1â
Biphase coded signal
t
01234567 01234567
Biphase detection
Noise detection
a
aâ a
b
bâ b
a
aâ a
b
bâ b
Figure 6-2. Biphase coding and error detection
6.7 Message validation
The communication between the MCU and the selected device is valid
when the MCU reads a pull data field having correct codes (excluding
the codes â111â and â000â) followed by a square wave signal, having a
frequency of 20kHz, contained in the end-of-frame information.
An MI BUS error is detected when the pull field contains the code â111â
followed by the end-of-frame permanently tied to logical state â1â. This
means that the communication between the MCU and the selected
device was not accomplished.
MC68HC11P2 â Rev 1.0
Motorola Interconnect Bus (MI BUS)
For More Information On This Product,
Go to: www.freescale.com
Technical Data
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