XR88C681CP/40 Exar Corporation, XR88C681CP/40 Datasheet - Page 73

• Manufacturer Part Number: XR88C681CP/40
• Description: Dual Channel UART
• Manufacturer: Exar Corporation

Specifications of XR88C681CP/40

• Features: *
• Number Of Channels: 2, DUART
• Fifo's: 1 Byte, 3 Byte
• Voltage - Supply: 5V
• With Parallel Port: Yes
• With Cmos: Yes
• Mounting Type: Through Hole
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MR2n[7:6] - Channel Mode Select
Each Channel can operate in one of four modes.
D Setting MR2n[7:6] = 00 configures the channel to op-
erate in the Normal Mode. In this mode, the receiver
and transmitter operate independently.
presents a diagram depicting Normal Mode Opera-
tion.
Rev. 2.11
Incoming
Serial Data
Receive Holding
Register
RXDn
(To be read by the CPU)
Receive Shift Register
Figure 38. A Block Diagram Depicting Normal Mode Operation.
To Data Bus
8
Figure 38
RXCn
73
TXCn
D Setting MR2n[7:6] = 01 places the channel in the Auto-
matic Echo Mode, which automatically re-transmits
the received data. Figure 39 presents a diagram de-
picting Automatic Echo Mode Operation. The follow-
ing conditions apply while in this mode.
(Parallel data from the CPU)
Transmit Shift Register
From Data Bus.
8
XR88C681
TXDn
Transmit Holding
Register
Outgoing Serial
Data