Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-213
SCCs
COMMUNICATION
16
PROCESSOR MODULE
16.9.15.13 FRACTIONAL STOP BITS. You can program the asynchronous UART
transmitter to transmit fractional stop bits. Using four bits in the SCCx UART data
synchronization register (DSR–SCC UART), you can program the length of the last stop bit
to be transmitted. These bits can be modified at any time and if two stop bits are transmitted,
only the second one is affected. Idle characters are always transmitted as full-length
characters.
FSB—Fractional Stop Bit
The value you programmed into the TDCR determines the set of values to use here. When
a serial communication controller is in UART mode with 32x oversampling, the FSB field is
decoded as follows in the DSR–SCC UART.
1111 = Last transmitted stop bit 32/32. Default value after reset.
1110 = Last transmitted stop bit 31/32.
1101 = Last transmitted stop bit 30/32.
1100 = Last transmitted stop bit 29/32.
1011 = Last transmitted stop bit 28/32.
1010 = Last transmitted stop bit 27/32.
1001 = Last transmitted stop bit 26/32.
1000 = Last transmitted stop bit 25/32.
0111 = Last transmitted stop bit 24/32.
0110 = Last transmitted stop bit 23/32.
0101 = Last transmitted stop bit 22/32.
0100 = Last transmitted stop bit 21/32.
0011 = Last transmitted stop bit 20/32.
0010 = Last transmitted stop bit 19/32.
0001 = Last transmitted stop bit 18/32.
0000 = Last transmitted stop bit 17/32.
DSR–SCC UART
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD X FSB XXXXXXXXXXX
RESET 0 1 11001111110
R/W R/W R/W R
ADDR (IMMR & 0xFFF0000) + 0xA2E
NOTE: X = “Don’t Care”.
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