xr88c681 Exar Corporation, xr88c681 Datasheet - Page 89

• Manufacturer Part Number: xr88c681
• Description: Cmos Dual Channel Uart Duart
• Manufacturer: Exar Corporation

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