MC68HC11P2 Datasheet, PDF (114/268 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Motorola Interconnect Bus (MI BUS)
6.7.1 Controller detected errors
There are three different MI BUS error types which are detected by the
selected slave device and are not mutually exclusive. The MCU cannot
determine which error occurred.
Noise error Slave devices take two samples in each time slot of
the biphase encoded push field. An error occurs when the two
samples for each time slot are not the same logical level.
Biphase error Slave devices receiving the push field detect the
biphase code. An error occurs when the two time slots of the
biphase code do not yield a logical exclusive-OR function.
Field error A field error is detected when the fixed-form of the
push field is violated.
6.7.2 MCU detected errors
There is a fourth error that can be detected by the MCU. This error
causes the noise flag (NF) to be asserted in the S2SR1 (or S3SR1)
register during the push field sequence.
Bit error A bit error can be detected by the MCU during the push
field. The MI BUS serial system monitors the bus via on-chip
hardware at the RXD pin at the same time as sending data. A bit
error is detected at that bit time when the value monitored is
different from the bit value sent.
Technical Data
Motorola Interconnect Bus (MI BUS)
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MC68HC11P2 — Rev 1.0