SCC Asynchronous HDLC Mode and IrDA
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
25-9
Table 25-7
describes SCCE/SCCM fields.
25.13.2 SCC Asynchronous HDLC Status Register (SCCS)
The SCC asynchronous HDLC status register (SCCS), shown in
Figure 25-5
, monitors the real-time status
of RXD. The real-time status of CTS and CD is part of the port C parallel I/O.
Table 25-7. SCCE/SCCM Field Descriptions
Bits
Name
Description
0–2
—
Reserved, should be cleared.
3
GLR
Glitch on Rx. Set when the SCC finds a Rx clock glitch.
4
GLT
Glitch on Tx. Set when the SCC finds a Tx clock glitch.
5–6
—
Reserved, should be cleared.
7
IDL
Idle sequence status changed. Set when serial line status changes. Real-time status can be read in
SCCS[ID].
8
—
Reserved, should be cleared.
9
BRKE
Break end. Marks the end of a break sequence—set when an idle bit is detected after a break
sequence.
10
BRKS
Break start. Set when the first break character of a break sequence is received. Only one BRKS
event occurs per break sequence, no matter the length of the sequence.
11
TXE
Tx error. Set when an error occurs on the transmitter channel.
12
RXF
Rx frame. Set when the number of frames specified in RFTHR are received. RXF is set no sooner
than when the midpoint of the closing flag’s stop bit arrives.
13
BSY
Busy condition. Set when a frame is received and discarded due to a buffer shortage.
14
TXB
Transmit buffer. Set when a buffer with TxBD[I] set is sent on the channel, not before the last bit of
the closing flag begins its transmission if the buffer is the last one in the frame. Otherwise, TXB is
set after the last byte of the buffer is written to the Tx FIFO.
15
RXB
Rx buffer. Set when a buffer with RxBD[I] set and RxBD[L] cleared is received over the channel.
0
6
7
Field
—
ID
Reset
0000_0000_0000_0000
R/W
R
Addr
0xA37 (SCCS2), 0xA57 (SCCS3), 0xA77 (SCCS4)
Figure 25-5. SCC Status Register for Asynchronous HDLC Mode (SCCS)
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