Motorola MPC823e - Page 663

Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-209
SCCs
COMMUNICATION
16
PROCESSOR MODULE
16.9.15.8 SCCx UART CONTROL CHARACTERS. The SCCx UART controller can
recognize special control characters that can be used in a message-oriented environment.
You can define a maximum of eight control characters in the control characters table. Each
character can either be written to the receive buffer or rejected. If it is rejected, the character
is written to the received control character register in internal RAM and a maskable interrupt
is generated. With this method, you know when the control characters (XON or XOFF) that
are not part of the received messages have arrived. The SCCx UART controller uses a table
of 16-bit entries to support control character recognition and each entry consists of the
control character, a valid bit, and a reject character bit.
Figure 16-75. Two UART Multidrop Mode Configuration Examples
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
SCCX BASE + 50 E R—————— CHARACTER1
SCCX BASE + 52 E R—————— CHARACTER2
SCCX BASE + 54 E R—————— CHARACTER3
•
•
•
SCCX BASE+ 5E E R—————— CHARACTER8
SCCX BASE+ 60 1 1 —————— RCCM
SCCX BASE + 62 ———————— RCCRP
UADDR1
UADDR2
TR
TR
TR
TR
1
2
3
4
TR TR TR
TR
MASTER SLAVE 1 SLAVE 2 SLAVE 3
TWO 8-BIT ADDRESSES
CAN BE AUTOMATICALLY
RECOGNIZED IN EITHER
CONFIGURATION.
CHOOSE WIRED-OR
OPERATION IN THE PORT A
OPEN-DRAIN REGISTER TO
ALLOW MULTIPLE TRANSMIT
PINS TO BE DIRECTLY
CONNECTED.
R
+V
R
+V
PAODR