xr68c681 Exar Corporation, xr68c681 Datasheet - Page 42

• Manufacturer Part Number: xr68c681
• Description: Cmos Dual Channel Uart Duart
• Manufacturer: Exar Corporation

Note:
G. SERIAL CHANNELS A and B
OPCR only addresses the alternate functions for output port pins, OP7 - OP2. OP0 and OP1 assume their RTS roles if either
MR1n[7] = 1 or MR2n[5] = 1. Setting those mode register bits enables the RTS function. Otherwise, these two ports will only be
general purpose output ports.
XR68C681
Output Port
Bit 7
OP7
RTSA:
RTSB:
TXCA_16X Output:
TXCA_1X Output:
RXCA_1X: Output:
TXCB_1X Output:
RXCB_1X Output:
C/T_1_RDY:
when used as the Counter/Timer Ready Output.
RXRDY/FFULL_A Output:
RXRDY/FFULL_B Output:
TXRDY_A Output:
TXRDY_B Output:
Bit 6
OP6
Table 15. Listing of the Alternate Functions for the Output Port
Table 16. Output Port Configuration Register - OPCR
Bit 5
OP5
Bit 4
OP4
Alternate Function(s)
Bit 3
Note: This output is an Open-Drain output
OP3
Bit 2
Bit 1
OP2
Bit 0