XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 247

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

15.8.5.3 Transmitting a Message in Block Mode
15.8.5.4 J1850 Bus Errors
M68HC12B Family — Rev. 8.0
MOTOROLA
data bytes. All other features of the frame remain the same, including the SOF,
CRC, and EOD symbols.
Another node wishing to send a block mode transmission must first inform all other
nodes on the network that this is about to happen. This is usually accomplished by
sending a special predefined message.
A block mode message is transmitted inherently by simply loading the bytes one
by one into the BDR until the message is complete. The programmer should wait
until the TDRE flag (see
a new byte of data into the BDR. The BDLC does not contain any predefined
maximum J1850 message length requirement.
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 ceases
transmitting. The error condition is reflected in the BSVR (see
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. The CRC code detects 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 (in BSVR) is set when a CRC error is detected. (See
Vector
Symbol error — A symbol error is detected when an abnormal (invalid) symbol is
detected in a message being received from the J1850 bus. The invalid symbol is
set when a symbol error is detected. (See
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 symbol
invalid, or the out-of-range flag, is set when a framing error is detected. (See
BDLC State Vector
Bus fault — If a bus fault occurs, the response of the BDLC depends upon the type
of bus fault.
Register.)
Byte Data Link Communications (BDLC)
Register.)
15.9.3 BDLC State Vector
15.9.3 BDLC State Vector
Byte Data Link Communications (BDLC)
Register) is set prior to writing
15.9.3 BDLC State
BDLC Protocol Handler
Table
15-1). If the
Register.)
Data Sheet
15.9.3
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