MC68HC58 Motorola, MC68HC58 Datasheet - Page 78

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

CCBR — Completion Code Byte Register
5.4.1 ERRF — Error Bit
5.4.2 RFO — Receive FIFO Overrun Bit
5.4.3 TMS[5:4] — Transmitter Status Field
5.4.3.1 Transmitter Not Involved
5.4.3.2 Transmitter Underrun
5-12
MOTOROLA
RESET
This bit indicates whether the receiver detected an error during the frame. When ERRF
is set, the ERRC field indicates which error occurred.
When the RFO bit is set, a RxFIFO buffer overrun has occurred. This means that the
host MCU has not read the RxFIFO buffer regularly enough to prevent incoming frame
bytes from being lost. RFO is set when the first bit of the 21st data byte is received.
Previously received data bytes remain in the buffer. When RFO is set, no other com-
pletion code bits can be considered valid. There is no way to detect BREAK when the
buffer has overflowed.
This bit field shows transmitter status during the frame just received. Table 5-7 shows
transmitter status field encoding.
This value indicates that the transmitter did not perform J1850 bus contention for this
frame. Frame did not originate from this node.
This value indicates that a frame was transmitted but was not completed. This is not
an indication that the transmission lost J1850 bus contention.
0 = No error occurred
1 = Error occurred
0 = No receiver buffer overrun occurred
1 = Receiver buffer overrun occurred
ERRF
7
0
Value
00
01
10
11
RFO
6
0
Table 5-7 TMS Field Encoding
CONTROL AND STATUS CODES
5
0
TMS
Transmitter lost arbitration
Transmitter not involved
Transmitter successful
Transmitter underrun
4
0
Description
IFR
3
0
IFRC
2
0
TECHNICAL DATA
1
0
ERRC
MC68HC58
0
0