Motorola MPC823e - Page 645

Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-191
SCCs
COMMUNICATION
16
PROCESSOR MODULE
If the CTSx pin is programmed to envelope the data, it must remain asserted during frame
transmission or a CTSx
lost error occurs. Negation of the CTSx pin forces the RTSx pin high
and the transmit data to an idle state. If the CTSS bit in the GSMR_H is zero, the CTSx
pin
must be sampled by a serial communication controller before a CTSx
lost is recognized.
Otherwise, the negation of CTSx
immediately causes the CTSx lost condition. Refer to
Figure 16-68 for details.
Figure 16-68. CTSx
Lost in Synchronous Protocols
Note: If the CTSS bit in the GSMR_H is set, all CTSx transitions must occur while the
transmit clock is low.
TXDx
RTSx
CTSx
FIRST BIT OF FRAME DATA
(INPUT)
TCLK
(OUTPUT)
(OUTPUT)
NOTE: CTSS is set to 1 in the GSMR. CTSP is set to 0 or no CTS lost can occur.
TXDx
RTSx
CTSx
FIRST BIT OF FRAME DATA
(INPUT)
TCLK
(OUTPUT)
(OUTPUT)
CTSx SAMPLED LOW HERE CTSx SAMPLED HIGH HERE
RTSx FORCED HIGH
DATA FORCED HIGH
CTS LOST SIGNALED IN FRAME BD
CTS LOST SIGNALED IN FRAME BD
DATA FORCED HIGH
NOTE: CTSS is set to 1 in the GSMR. CTSP is set to 0 or no CTS lost can occur.
RTSx FORCED HIGH