
Byte Data Link Controller-Digital (BDLC-D)
Data Sheet
MC68HC08AS32A — Rev. 1
90
Byte Data Link Controller-Digital (BDLC-D)
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MOTOROLA
The BDLC supports the in-frame response (IFR) feature of J1850 by setting
these bits correctly. The four types of J1850 IFR are shown below. The purpose
of the in-frame response modes is to allow multiple nodes to acknowledge
receipt of the data by responding with their personal ID or physical address in a
concatenated manner after they have seen the EOD symbol. If transmission
arbitration is lost by a node while sending its response, it continues to transmit
its ID/address until observing its unique byte in the response stream. For VPW
modulation, because the first bit of the IFR is always passive, a normalization
bit (active) must be generated by the responder and sent prior to its ID/address
byte. When there are multiple responders on the J1850 bus, only one
normalization bit is sent which assists all other transmitting nodes to sync up
their response.
Figure 4-20. Types of In-Frame Response (IFR)
Table 4-4. BDLC Transmit In-Frame Response
Control Bit Priority Encoding
Write/Read
TSIFR
Write/Read
TMIFR1
Write/Read
TMIFR0
Actual
TSIFR
Actual
TMIFR1
Actual
TMIFR0
0
0
0
0
0
0
1
X
X
1
0
0
0
1
X
0
1
0
0
0
1
0
0
1
S
HEADER
DATA FIELD
CRC
E
TYPE 0 — NO IFR
HEADER
DATA FIELD
CRC
E
TYPE 3 — MULTIPLE BYTES TRANSMITTED FROM A SINGLE RESPONDER
HEADER
DATA FIELD
CRC
E
TYPE 1 — SINGLE BYTE TRANSMITTED FROM A SINGLE RESPONDER
HEADER
DATA FIELD
CRC
E
TYPE 2 — SINGLE BYTE TRANSMITTED FROM MULTIPLE RESPONDERS
ID1
ID N
IFR DATA FIELD
CRC
NB
NB
NB
ID
S
S
S
E
E
E
E
E
E
E
(OPTIONAL)
NB = Normalization Bit
ID = Identifier (usually the physical address of the responder(s))
F
Freescale Semiconductor, Inc.
n
.