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SYN—Synchronous Mode
0 = Normal asynchronous operation. Normally, you program the TENC and RENC
fields in the GSMR_L to NRZ and select either 8 × , 16 × , or 32 × in the RDCR and
TDCR fields of the GSMR_L. 16 × is the recommended value for most applications.
1 = Synchronous SCCx UART controller using 1 × clock. Normally, you program the
TENC and RENC fields in the GSMR_L to NRZ and set the RDCR and TDCR fields
in the GSMR_L to 1 × mode. A 1 bit is transferred with each clock and is
synchronous to the clock. As with the other modes, the clock can be provided
internally or externally. This mode is sometimes referred to as isochronous UART
channel operation.
DRT—Disable Receiver While Transmitting
0 = Normal operation.
1 = While the SCCx UART controller is transmitting data, the receiver is disabled. This
is useful if the SCCx UART controller is configured onto a multidrop line and you
do not want to receive your transmission.
Note: You must set the P bit in the transmit buffer descriptor if you are using the
MPC823e in multidrop UART mode.
Bit 10—Reserved
This bit is reserved and must be set to 0.
PEN—Parity Enable
0 = No parity.
1 = Parity is enabled and determined by the RPM and TPM bits.
RPM—Receiver Parity Mode
This field selects the type of parity check that the receiver will perform. It can be modified
on-the-fly.
00 = Odd parity.
01 = Low parity. Always check for a zero in the parity bit position.
10 = Even parity.
11 = High parity. Always check for a one in the parity bit position.
When odd parity is selected, the transmitter counts the number of ones in the data word. If
the total number of ones is not an odd number, the parity bit is set to 1 and produces an odd
number. If the receiver counts an even number of ones, an error in transmission has
occurred. In the same manner, for even parity, an even number must result from the
calculation performed at both ends of the line. In high or low parity (also called mark or space
parity), if the parity bit is not high or low, a parity error is reported.
MOTOROLA
MPC823e REFERENCE MANUAL
Communication Processor Module
16-219
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