MC68HC08AS32 Datasheet, PDF (349/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Byte Data Link Controller-Digital (BDLC-D)
BDLC Protocol Handler
20.6.5.4 J1850 Bus Errors
The BDLC detects several types of transmit and receive errors which
can occur during the transmission of a message onto the J1850 bus.
Transmission Error
If the message transmitted by the BDLC contains invalid bits or
framing symbols on non-byte boundaries, this constitutes a
transmission error. When a transmission error is detected, the BDLC
immediately will cease transmitting. The error condition ($1C) is
reflected in the BSVR register (see Table 20-6). If the interrupt enable
bit (IE in BCR1) is set, a CPU interrupt request from the BDLC is
generated.
CRC Error
A cyclical redundancy check (CRC) error is detected when the data
bytes and CRC byte of a received message are processed and the
CRC calculation result is not equal to $C4. The CRC code will detect
any single and 2-bit errors, as well as all 8-bit burst errors and almost
all other types of errors. The CRC error flag ($18 in BSVR) is set when
a CRC error is detected. (See 20.7.4 BDLC State Vector Register.)
Symbol Error
A symbol error is detected when an abnormal (invalid) symbol is
detected in a message being received from the J1850 bus. However,
if the BDLC is transmitting when this happens, it will be treated as a
loss of arbitration ($14 in BSVR) rather than a transmitter error. The
($1C) symbol invalid or the out-of-range flag is set when a symbol
error is detected. Therefore, ($1C) symbol invalid flag is stacked
behind the ($14) LOA flag during a transmission error process. (See
20.7.4 BDLC State Vector Register.)
Framing Error
A framing error is detected if an EOD or EOF symbol is detected on a
non-byte boundary from the J1850 bus. A framing error also is
detected if the BDLC is transmitting the EOD and instead receives an
active symbol. The ($1C) symbol invalid or the out-of-range flag is set
when a framing error is detected. (See 20.7.4 BDLC State Vector
Register.)
MC68HC08AS32 — Rev. 3.0
MOTOROLA
Byte Data Link Controller-Digital (BDLC-D)
Advance Information
349