
Serial Communication Controllers (SCCs)
MC68360 USER’S MANUAL
7.10.17.13 SCC STATUS REGISTER (SCCS). The SCCS is an 8-bit read-only register that
allows the user to monitor real-time status conditions on the RXD line. The real-time status
of the CTS and CD pins are part of the port C parallel I/O.
Bits 7–3—Reserved
FG—Flags
While FG is cleared, the most recently received 8 bits are examined every bit time to see
if a flag is present. FG is set as soon as an HDLC flag ($7E) is received on the line. Once
FG is set, it will remain set at least 8 bit times, at which time the next 8 received bits are
examined. If another flag occurs, then FG remains set for at least another eight bits; oth-
erwise, FG is cleared and the search begins again.
The examination of the line is made after the data has been decoded by the DPLL.
0 = HDLC flags are not currently being received.
1 = HDLC flags are currently being received.
CS—Carrier Sense (DPLL)
This bit shows the real-time carrier sense of the line as determined by the DPLL, if it is
used.
0 = The DPLL does not sense a carrier.
1 = The DPLL does sense a carrier.
ID—Idle Status
ID is set when the RXD pin is a logic one for 15 or more consecutive bit times; it is cleared
after a single logic zero is received.
0 = The line is not currently idle.
1 = The line is currently idle.
7.10.17.14 SCC HDLC EXAMPLE #1. The following list is an initialization sequence for an
SCC HDLC channel assuming an external clock is provided. SCC4 is used. The HDLC con-
troller is configured with the RTS4, CTS4, and CD4 pins active. The CLK7 pin is used for
both the HDLC receiver and transmitter.
1. The SDCR (SDMA Configuration Register) should be initialized to $0740, rather than
being left at its default value of $0000.
2. Configure the port A pins to enable the TXD4 and RXD4 pins. Write PAPAR bits 6
and 7 with ones. Write PADIR bits 6 and 7 with zeros. Write PAODR bits 6 and 7
with zeros.
3. Configure the port C pins to enable RTS4, CTS4, and CD4. Write PCPAR bit 3 with
one, and bits 10 and 11 with zeros. Write PCDIR bits 3, 10 and 11 with zeros.
Write PCSO bits 10 and 11 with ones.
4. Configure port A to enable the CLK7 pin. Write PAPAR bit 14 with a one. Write
PADIR bit 14 with a zero.
76543210
—————
FG
CS
ID
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.