Motorola MPC860 PowerQUICC User Manual page 669

Table 23-4. Control Character Table, RCCM, and RCCR Descriptions (Continued)
Offset Bits Name
0x60 0Ð1 0b11
2Ð7 Ñ
8Ð15 RCCM
0x62 0Ð7 Ñ
8Ð15 RCCR
23.10 Hunt Mode (Receiver)
A UART receiver in hunt mode remains deactivated until an idle or address character is
recognized, depending on PSMR[UM]. A receiver is forced into hunt mode by issuing an
command.
ENTER HUNT MODE
The receiver aborts any message in progress when
message is Þnished, the receiver is reenabled by detecting the idle line (one idle character)
or by the address bit of the next message, depending on PSMR[UM]. When a receiver in
hunt mode receives a break sequence, it increments BRKEC and generates a BRK interrupt
condition.
23.11 Inserting Control Characters into the Transmit
Data Stream
The SCC UART transmitter can send out-of-sequence, ßow-control characters like XON
and XOFF. The controller polls the transmit out-of-sequence register (TOSEQ), shown in
Figure 23-4, whenever the transmitter is enabled for UART operation, including during a
UART freeze operation, UART buffer transmission, and when no buffer is ready for
transmission. The TOSEQ character (in CHARSEND) is sent at a higher priority than the
other characters in the transmit buffer, but does not preempt characters already in the
transmit FIFO. This means that the XON or XOFF character may not be sent for eight
(SCC1) or four (SCC2ÐSCC4) character times. To reduce this latency, set GSMR_H[TFL]
to decrease the FIFO size to one character before enabling the transmitter.
MOTOROLA
Part V. The Communications Processor Module
Must be set. Used to mark the end of the control character table in case eight
characters are used. Setting these bits ensures correct operation during control
character recognition.
Reserved
Received control character mask. Used to mask the comparison of
CHARACTERn. Each RCCM bit corresponds to the respective bit of
CHARACTERn and decodes as follows.
0 Ignore this bit when comparing the incoming character to CHARACTERn.
1 Use this bit when comparing the incoming character to CHARACTERn.
Reserved
Received control character register. If the newly arrived character matches and is
rejected from the buffer (R = 1), the PIP controller writes the character into the
RCCR and generates a maskable interrupt. If the core does not process the
interrupt and read RCCR before a new control character arrives, the previous
control character is overwritten.
Chapter 23. SCC UART Mode
Description
is issued. When the
ENTER HUNT MODE
23-9