MC68HC58 Motorola, MC68HC58 Datasheet - Page 68

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

5.1.1.1 Do Nothing
5.1.1.2 Enter Standby Mode
5.1.1.3 Send BREAK Symbol
5.1.1.4 Send IFR on EOD with CRC
5-2
MOTOROLA
The “do nothing” command indicates to the DLC that a general command should not
be executed.
The “enter standby mode” command causes the DLC to operate in low power con-
sumption (standby) mode.
If the J1850 bus is not idle when this command is latched, the DLC becomes inactive
within 5 s after the J1850 bus goes idle.
If the J1850 bus is idle when this command is latched, the DLC goes into standby
mode immediately.
Toggling the CS line after this command has been latched, but before the DLC has
entered standby mode, clears the command.
When the “send BREAK symbol” command is latched in, the DLC immediately sends
a BREAK symbol on the J1850 bus, regardless of current status of the transmitter.
The “send IFR on EOD with CRC” command causes the DLC to clear the transmitter
and the TxFIFO buffer, terminate automatic frame retry, and originate an IFR with a
CRC. This command must accompany a data byte, and the command BTAD field must
indicate either “load as first byte of transmit data” or “load as first and last byte of trans-
mit data”. The subsequent bytes in the same IFR must not be accompanied by this
command.
If this command is latched after an EOD has already occurred, the IFR is not transmit-
ted, and is lost. When this occurs, the DLC status byte indicates that the TxFIFO buffer
is empty, and the DLC does not terminate automatic retry.
Table 5-1 General Command Summary
Value
000
001
010
011
100
101
110
111
CONTROL AND STATUS CODES
Send IFR on EOD without CRC
Send IFR on EOD with CRC
Terminate automatic retry
Send BREAK symbol
Enter standby mode
Abort transmission
Description
Do nothing
Reserved
TECHNICAL DATA
MC68HC58