MC68HC58 Motorola, MC68HC58 Datasheet - Page 76

• Manufacturer Part Number: MC68HC58
• Description: Data Link Controller
• Manufacturer: Motorola

5.3.1.5 One Byte in Buffer
5.3.1.6 Completion Code at Head of Buffer, More Bytes Available
5.3.1.7 Completion Code at Head of Buffer, Frame Available
5.3.1.8 Completion Code Only at Head of Buffer
5.3.2 DLI — Data Link Idle Bit
5.3.3 NETF — Network Fault Bit
5-10
MOTOROLA
This value indicates that the RxFIFO buffer contains one byte that is not a completion
code.
This value indicates that there is a completion code at the head of the RxFIFO buffer,
and additional bytes but no additional completion codes are in the buffer.
This value indicates that there is a completion code at the head of the RxFIFO buffer,
and additional bytes and an additional completion code are in the buffer.
This value indicates that there is a completion code at the head of the RxFIFO buffer,
and no additional bytes are in the buffer. Indication usually occurs after execution of a
flush frame command.
DLI is set when the J1850 bus is idle. DLI is cleared when the J1850 bus has been
active for longer than the digital filter time constant, or when an EOD symbol is being
timed by the receive logic. Once cleared, DLI does not go to logic level one until an
EOD symbol has been received. If the J1850 bus remains active for longer than the
minimum BREAK symbol definition, a completion code indicating a break has oc-
curred is placed in the RxFIFO buffer. A prolonged data link active indication may in-
dicate that the J1850 bus is shorted to 12 Vdc.
This value indicates the DLC J1850 bus connection is shorted to ground. When a hard-
ware fault prevents the DLC receiver from sensing an active state after the transmitter
has driven the J1850 bus for 60 s, NETF is set. After NETF is set, only an Abort
Transmission command or assertion of the DLC RST input can restart the DLC.
When the short is momentary, it is appropriate to try reloading and retransmission.
However, if the problem is a defective receiver, retransmission could corrupt another
frame.
0 = SAE J1850 bus is active
1 = SAE J1850 bus is idle
0 = Active state occurred before 60 s
1 = Active state not sensed after 60 s
CONTROL AND STATUS CODES
TECHNICAL DATA
MC68HC58