Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 681

Table 22-4. Control Character Table, RCCM, and RCCR Descriptions (continued)
Offset Bits Name
0x60 0–1 0b11
2–7
8–15 RCCM
0x62 0–7
8–15 RCCR
22.10 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.
The receiver aborts any message in progress when
finished, 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.
22.11 Inserting Control Characters into the Transmit Data Stream
The SCC UART transmitter can send out-of-sequence, flow-control characters like XON and XOFF. The
controller polls the transmit out-of-sequence register (TOSEQ), shown in
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 four
(SCC2–SCC4) character times. To reduce this latency, set GSMR_H[TFL] to decrease the FIFO size to
one character before enabling the transmitter.
Freescale Semiconductor
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
CHARACTER n . Each RCCM bit corresponds to the respective bit of
CHARACTER n and decodes as follows.
0 Ignore this bit when comparing the incoming character to CHARACTER n .
1 Use this bit when comparing the incoming character to CHARACTER n .
— 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.
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Description
is issued. When the message is
ENTER HUNT MODE
Figure
SCC UART Mode
ENTER HUNT MODE
22-4, whenever the
22-9