Datasheet

Freescale Interconnect Bus
Technical Data MC68HC912D60A — Rev. 3.1
292 Freescale Interconnect Bus Freescale Semiconductor
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.
‘0’ ‘1’
01234567 01234567
t
Biphase coded signal
Biphase detection
Noise detection
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a’ b’a b a’ b’ab