XR88C681J-F Datasheet, PDF (89/101 Pages) Exar Corporation – Two Full Duplex, Independent Channels

XR88C681
Bit 7
Bit 6
Channel Mode
00 = Normal
01 = Auto Echo
10 = Local Loop
11 = Remote Loop
Bit 5
Tx RTS
Control
0 = No
1 = Yes
Bit 4
CTS Enable
Tx
0 = No
1 = Yes
Bit 3
Bit 2
Bit 1
Stop Bit Length
Bit 0
0h = 0.563
1h = 0.625
2h = 0.688
3h = 0.750
4h = 0.813
5h = 0.875
6h = 0.938
7h = 1.000
8h = 1.563
9h = 1.625
Ah = 1.688
Bh = 1.750
Ch = 1.813
Dh = 1.875
Eh = 1.938
Fh = 2.000
Table 30. Mode Register 2: MR2A, MR2B
Bit 7
Bit 6
Bit 5
Receiver Clock Select
See Table 9
Bit 4
Bit 3
Bit 2
Bit 1
Transmitter Clock Select
See Table 9
Table 31. Clock Select Registers: CSRA, CSRB
Bit 0
Bit 7
Bit 6
Bit 5
Miscellaneous Commands
See Text in Section B.2.
Bit 4
Bit 3
Bit 2
Enable/Disable Tx
00 = No Change
01 = Enable Tx
10 = Disable Tx
11 = Not Allowed
(Do Not Use)
Table 32. Command Registers: CRA, CRB
Bit 1
Bit 0
Enable/Disable Rx
00 = No Change
01 = Enable Tx
10 = Disable Tx
11 = Not Allowed
(Do Not Use)
Bit 7
Received
Break
0 = No
1 = Yes
Bit 6
Framing
Error
0 = No
1 = Yes
Bit 5
Parity Error
0 = No
1 = Yes
Bit 4
Overrun
Error
0 = No
1 = Yes
Bit 3
TXEMT
0 = No
1 = Yes
Bit 2
TXRDY
0 = No
1 = Yes
Table 33. Status Registers: SRA, SRB
Bit 1
FFULL
0 = No
1 = Yes
Bit 0
RXRDY
0 = No
1 = Yes
Bit 7
OP7
0=OPR[7]
1=TXRDYB
Bit 6
OP6
0=OPR[6]
1=TXRDYA
Bit 5
OP5
0=OPR[5]
1=RXRDY/
FFULLB
Bit 4
OP4
0=OPR[4]
1=RXRDY/
FFULLA
Bit 3
Bit 2
OP3
00 = OPR[3]
01 = C/T #1 Output
10 = TXCB (1X)
11 = RXCB (1X)
Table 34. Output Port Configuration Register: OPCR
Rev. 2.11
89
Bit 1
Bit 0
OP2
00 = OPR[2]
01 = TXCA (16X)
10 = TXCA (1X)
11 = RXCA (1X)