XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 502

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

Byte Data Link Controller (BDLC)
Technical Data
502
Valid EOF and IFS Symbol
Idle Bus
ACTIVE
PASSIVE
ACTIVE
PASSIVE
In
beginning the SOF symbol of the next message occurs between a
and b, the current symbol will be considered a valid end-of-frame
(EOF) symbol.
See
beginning the SOF symbol of the next message occurs between c
and d, the current symbol will be considered a valid EOF symbol
followed by a valid inter-frame separation symbol (IFS). All nodes
must wait until a valid IFS symbol time has expired before beginning
transmission. However, due to variations in clock frequencies and bus
loading, some nodes may recognize a valid IFS symbol before others
and immediately begin transmitting. Therefore, any time a node
waiting to transmit detects a passive-to-active transition once a valid
EOF has been detected, it should immediately begin transmission,
initiating the arbitration process.
In
beginning the start-of-frame (SOF) symbol of the next message does
not occur before d, the bus is considered to be idle, and any node
wishing to transmit a message may do so immediately.
Figure
Figure
Figure
Byte Data Link Controller (BDLC)
27-8(1), if the passive-to-active received transition
27-8(2), if the passive-to-active received transition
Figure 27-8. J1850 VPW Received Passive
27-8(2). If the passive-to-active received transition
280 µ s
EOF and IFS Symbol Times
300 µ s
a
b
c
MC68HC908AZ60A — Rev 2.0
d
(1) VALID EOF SYMBOL
(2) VALID EOF+
IFS SYMBOL
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