CD2231 Intel Corporation, CD2231 Datasheet - Page 79

• Manufacturer Part Number: CD2231
• Description: CD2231 Intelligent Two-channel Lan And Wan Communications Controller
• Manufacturer: Intel Corporation

6.5.5
6.5.6
Datasheet
Table 15. SSPC[x] Settings
Table 16. SCdet Settings
Special Character Recognition and Special Character Range
Special character recognition is enabled when the SCDE (Special Character Detection) bit
(COR3[4]) is set to ‘1’. The special characters are programmed in the SCHR registers, and are the
same characters used for the transmitter.
If the FCT bit (COR3[5]) is set to ‘1’, the channel processes the flow-control characters and
discards them. If FCT is set to ‘0’, the received flow-control characters is processed and passed
onto the host by exception interrupt.
In the event of an error (framing and/or parity) in a received character sequence, the channel does
not interpret this character as a special character. But, if an overrun condition occurred after a
special character is detected, the new character is lost and the overrun status is set. In this
condition, the CD2231 gives both an overrun exception and a special character recognition status.
Special Character Range
The Special Character Range low and high (SCRl and SCRh) registers define an inclusive range
for special character recognition in Asynchronous mode. It is useful for identifying that a received
character is within a certain range, such as a control character. To disable this function, if special
character detection is enabled, make both SCRl and SCRh equal to Special Character #1 (SCHR1).
Special characters and range detection is through the three Special Character Detect bits
(RISR[6:4]) in the RISR register. The meanings of these bits are listed in
SCdet2
SSPC2
0
0
0
0
0
0
1
0
1
1
1
Intelligent Two-Channel LAN and WAN Communications Controller — CD2231
SCdet1
SSPC1
0
0
1
0
1
1
0
0
0
1
1
SCdet0
SSCP0
0
1
0
1
0
1
0
0
1
0
1
No special characters/range
detected
Special character 1 matched
Special character 2 matched
Send Special Character #1
Send Special Character #2
Send Special Character #3
Send Special Character #4
Reserved
Reserved
Reserved
Reserved
Function
Function
Table
16.
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