Serial Communication Controllers (SCCs)
MOTOROLA
MC68360 USER’S MANUAL
7-233
TX—Tx Buffer
A buffer has been transmitted. This bit is set no sooner than when the last bit of the last
byte of the buffer begins its transmission, assuming the L-bit of the Tx BD is set. If the L-
bit is not set, TX is set when the last byte of data is written to the transmit FIFO.
RX—Rx Buffer
A complete buffer has been received on the SCC channel. This bit is set no sooner than
two serial clocks after the last bit of the last byte in which the buffer is received on the RXD
pin.
7.10.21.12 TRANSPARENT MASK REGISTER (SCCM).
The SCCM is referred to as the
transparent mask register when the SCC is operating in transparent mode. It is a 16-bit read-
write register that has the same bit format as the transparent event register. If a bit in the
transparent mask register is a one, the corresponding interrupt in the event register will be
enabled. If the bit is zero, the corresponding interrupt in the event register will be masked.
This register is cleared upon reset.
7.10.21.13 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.
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.
7.10.21.14 SCC TRANSPARENT EXAMPLE.
The following list is an initialization se-
quence for an SCC transparent channel. The transmitter and receiver are both enabled, but
operate independently of each other; they implement the connection shown on QUICC 2 in
Figure 7-64. Both transmit and receive clocks are provided externally to QUICC 2 using the
CLK7 pin. SCC4 is used. The transparent controller is configured with the RTS4 and CD4
pins active. CTS4 is grounded internally by the configuration in port C. A 16-bit CRC-CCITT
is sent with each transparent frame. The FIFOs are configured for fast operation.
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 bit 11 with zero. Write PCDIR bits 3 and 11 with zero. Write PCSO bit 11
with one and bit 10 with zero.
4. Configure port A to enable the CLK7 pin. Write PAPAR bit 14 with a one. Write
7
—
6
—
5
—
4
—
3
—
2
—
1
0
—
CS