Freescale Semiconductor, Inc.
Motorola Interconnect Bus
‘0’
‘1’
Biphase coded signal
t
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
a
a
b
b
a
a
b
b
Biphase detection
Noise detection
a’
b’
a’
b’
Figure 16-2. Biphase coding and error detection
16.5 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 ‘111’ and ‘000’) 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 ‘111’
followed by the end-of-frame permanently tied to logical state ‘1’. This
means that the communication between the MCU and the selected
device was not accomplished.
Advance Information
266
68HC(9)12D60 — Rev 4.0
Motorola Interconnect Bus
MOTOROLA
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MOTOROLA [ MOTOROLA ]
