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MOTOROLA Chapter 20. SCC UART Mode 20-9

Part IV. Communications Processor Module

Table 20-4 describes the data structure used in control character recognition.

Offset

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

0x50 ER Ñ CHARACTER1

0x52 ER Ñ CHARACTER2

0x5E ER Ñ CHARACTER8

0x60 1 1 Ñ RCCM

0x62 Ñ RCCR

From SCCx base address

Figure 20-3. Control Character Table

Table 20-4. Control Character Table, RCCM, and RCCR Descriptions

Offset Bits Name Description

0x50Ð

0x5E

0 E End of table. In tables with eight control characters, E is always 0.

0 This entry is valid.

1 The entry is not valid and is not used.

1 R Reject character.

0 A matching character is not rejected but is written into the Rx buffer, which is

then closed. If RxBD[I] is set, the buffer closing generates a maskable interrupt

through SCCE[RX]. A new buffer is opened if more data is in the message.

1 A matching character is written to RCCR and not to the Rx buffer. A maskable

interrupt is generated through SCCE[CCR]. The current Rx buffer is not closed.

2Ð7 Ñ Reserved

8Ð15 CHARACTERn Control character values 1Ð8. DeÞnes control characters to be compared to the

incoming character. For characters smaller than 8 bits, the most signiÞcant bits

should be zero.

0x60 0Ð1 0b11 Must be set. Used to mark the end of the control character table in case eight

characters are used. Setting these bits ensures correct operation during control

character recognition.

2Ð7 Ñ Reserved

8Ð15 RCCM Received control character mask. Used to mask the comparison of

CHARACTERn. Each RCCM bit corresponds to the respective bit of

CHARACTERn and decodes as follows.

0 Ignore this bit when comparing the incoming character to CHARACTERn.

1 Use this bit when comparing the incoming character to CHARACTERn.

0x62 0Ð7 Ñ Reserved

8Ð15 RCCR Received control character register. If the newly arrived character matches and is

rejected from the buffer (R = 1), the PIP controller writes the character into the

RCCR and generates a maskable interrupt. If the core does not process the

interrupt and read RCCR before a new control character arrives, the previous

control character is overwritten.