MC68HC58 Motorola, MC68HC58 Datasheet - Page 77

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

5.3.4 4XMD — 4X Mode Bit
5.3.5 TMFS[1:0] — TxFIFO Status Field
5.3.5.1 Buffer Empty
5.3.5.2 Buffer Contains Data
5.3.5.3 Buffer Almost Full
5.3.5.4 Buffer Full
5.4 Completion Code Byte
MC68HC58
TECHNICAL DATA
This value indicates the DLC is operating in high-speed mode without waveshaping.
This mode is not used during normal operation.
This bit field shows the status of TxFIFO buffer. Table 5-6 shows the TxFIFO status
encoding field.
This value indicates there are no data bytes in TxFIFO buffer.
This value indicates that the TxFIFO buffer contains one to nine bytes of data.
This value indicates that the TxFIFO buffer contains ten bytes of data.
This value indicates that either the TxFIFO buffer contains 11 bytes of data (in block
transmission mode), or that it contains a byte that was accompanied by a “last byte”
command.
When a frame is complete, after the time period for an EOD symbol has elapsed, the
DLC generates a completion code byte and transfers it to the host MCU in the same
way that a received data byte is transferred. The accompanying status byte indicates
that it is a completion code byte.
The completion code byte contains an error flag, transmitter action codes, IFR codes,
and error codes. When a DLC is transmitting, completion code information applies to
both transmitter and receiver.
Any activity on the J1850 bus longer than the digital filter time constant causes a com-
pletion code byte to be placed in the RxFIFO buffer after the J1850 bus is idle for an
EOD length of time.
0 = DLC operating in normal mode
1 = DLC operating at 41.67 kbps
Value
00
01
10
11
Table 5-6 TMFS Field Encoding
CONTROL AND STATUS CODES
Buffer contains data bytes
Buffer almost full
Buffer empty
Description
Buffer full
MOTOROLA
5-11