Serial Communication Controllers (SCCs)
MOTOROLA
MC68360 USER’S MANUAL
7-113
NOTE
Full-duplex totally transparent operation for an SCC is obtained
by setting both TTX and TRX.
An SCC cannot operate with Ethernet on its transmitter simulta-
neously with transparent operation on its receiver, or erratic be-
havior will result. In other words, if the GSMR MODE = Ethernet,
TTX must equal TRX, or erratic operation will result.
TTX—Transparent Transmitter
The QUICC SCCs offer totally transparent operation. However, to increase flexibility, to-
tally transparent operation is not configured with the MODE bits, but with the TTX and
TRX bits. This gives the user the opportunity to implement unique applications, such as
an SCC receiver configured to HDLC and the transmitter configured to totally transparent
operation. To do this, set MODE = HDLC, TTX = 1, and TRX = 0.
0 = Normal operation.
1 = The transmitter operates in totally transparent mode, regardless of the protocol se-
lected for the receiver in the MODE bits.
NOTE
Full-duplex totally transparent operation for an SCC is obtained
by setting both TTX and TRX.
An SCC cannot operate with Ethernet on its receiver simulta-
neously with transparent operation on its transmitter, or erratic
behavior will result. In other words, if the GSMR MODE = Ether-
net, TTX must equal TRX, or erratic operation will result.
CDP—CD Pulse
0 = Normal operation—envelope mode. The CD pin should envelope the frame, and
negating CD while receiving will cause a CD lost error.
1 = Pulse mode. Once the CD pin is asserted, synchronization has been achieved, and
further transitions of CD will have no effect on reception.
This mode is similar to the way the CD (sync) pin is used on the MC68302 in totally trans-
parent mode. To mimic this behavior on the QUICC, the external sync signal should be
connected to the CD and CTS pins on the QUICC, and the CDP and CTSP bits should be
set.
NOTE
This bit must be set if this SCC is used in TSA.
CTSP—CTS Pulse
0 = Normal operation—envelope mode. The CTS pin should envelope the frame, and
a negation of CTS while transmitting will cause a CTS lost error.
1 = Pulse mode. Once the CTS pin is asserted, synchronization has been achieved,
and further transitions of CTS will have no effect on transmission.