XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 504

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

Byte Data Link Controller (BDLC)
27.5.5 Message Arbitration
Technical Data
504
Valid SOF Symbol
Valid BREAK Symbol
Message arbitration on the J1850 bus is accomplished in a non-
destructive manner, allowing the message with the highest priority to be
transmitted, while any transmitters which lose arbitration simply stop
transmitting and wait for an idle bus to begin transmitting again.
If the BDLC wants to transmit onto the J1850 bus, but detects that
another message is in progress, it waits until the bus is idle. However, if
multiple nodes begin to transmit in the same synchronization window,
message arbitration will occur beginning with the first bit after the SOF
symbol and will continue with each bit thereafter.
ACTIVE
PASSIVE
In
beginning the next data bit (or symbol) occurs between c and d, the
current symbol would be considered a valid SOF symbol.
In
not occur until after e, the current symbol will be considered a valid
BREAK symbol. A BREAK symbol should be followed by a start-of-
frame (SOF) symbol beginning the next message to be transmitted
onto the J1850 bus. See
BREAK symbols.
Figure 27-10. J1850 VPW Received BREAK Symbol Times
Figure
Figure
Byte Data Link Controller (BDLC)
27-10, if the next active-to-passive received transition does
27-9(4), if the active-to-passive received transition
240 µ s
J1850 Frame Format
e
MC68HC908AZ60A — Rev 2.0
for BDLC response to
(2) VALID BREAK SYMBOL
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